CN1403680A - Method for Determining Drilling Fluid Density and Equipment for Controlling Drilling Fluid Density - Google Patents

Abstract

The invention provides equipment for controlling the density of drilling fluid, which comprises the following devices: the device comprises a basic drilling parameter input device (1), an automatic drilling parameter measuring device (2), a drilling control machine (3) and drilling fluid density control devices (6 and 8). The invention also provides a method for determining the density of drilling fluid, which comprises the following steps: measuring formation pore pressure coefficient (xi) of each section of drilling well_i) (ii) a Measuring the length (L) of the open hole section; measuring the starting position (l) of each interval₁) And a termination site (l)₂) (ii) a Determining a formation pore pressure coefficient (P) of the borehole; and determining the density of the drilling fluid.

Description

Determine the method for drilling fluid density and the equipment of control drilling fluid density

Technical field

The present invention relates to drilling technology, particularly the definite method and the control appliance of drilling fluid density.

Background technology

One of main effect of drilling fluid is that the landwaste under the bit cutting is carried to ground in oil drilling, and is supporting the borehole wall and be unlikely and collapse.Therefore, the cyclic process of drilling fluid is important step of drilling engineering.

An important technology index of drilling fluid is its density.Drilling fluid density is too little, can cause blowout takes place in the drilling process, causes great machinery and personal injury, and drilling fluid density is too big, can cause the oil layer pollution on stratum again, can make barreler become stripper well, even oil dripping does not go out.

The important parameter of determining drilling fluid density is that formation pore pressure is determined.In general, formation pore pressure determined value height, then the drilling fluid density value is just higher, and vice versa.Because for a long time, carry out formation pore pressure and determine to belong to geologist's responsibility, and determine that drilling fluid density is the responsibility that belongs to spudder author, belong to two big specialized fields of oil sector, few people investigate definite problem of drilling fluid density from " joint portion " of these two specialized fields.

In February, 2000, at U.S. New Orleans, Louisiana (Louisiana State, Crescent City) holds world oil drilling well SPE/I ADC (Petroleum Engineer and international petroleum contractor) in 2000 annual meeting, the present inventor has at the meeting delivered English paper " SPE59263:Improvementon the Procedure in Exploration Well By Unbalanced Drilling:A Case Historyin BS7 Well in People ' s Republic of China " (with the drilling process of underbalance method improvement exploratory well and in the application of dark 7 wells of Chinese plate), and has independently proposed a new well kick process differential equation.

Summary of the invention

The invention provides a kind of equipment of controlling drilling fluid density, it comprises with lower device:

Basic drilling parameter input unit is used to import the length of barefoot interval;

The drilling parameter self-operated measuring unit is used to measure the length of original position, final position and each well section of each well section and the formation pore pressure coefficient of each section of drilling well;

The drilling well controller, its input links to each other with described drilling parameter self-operated measuring unit with described basic drilling parameter input unit, is used for determining the formation pore pressure coefficient and the drilling fluid density of drilling well, and output drilling fluid control signal;

The drilling fluid density control device is used for according to described drilling fluid control signal control drilling fluid density.

The present invention also provides a kind of method of definite drilling fluid density, and this method may further comprise the steps: (1) measures the formation pore pressure coefficient of each section of drilling well; (2) length of measurement barefoot interval; (3) measure the length of original position, final position and each well section of each well section; (4) determine the formation pore pressure coefficient of drilling well; (5) determine drilling fluid density.

1998, the present invention is in the design and construction of dark 7 wells of plate, from the combining of drilling engineering and drilling geology, rethink definite problem of drilling fluid density first, utilize the present invention to determine the stratum pore pressure coefficient, form the new drilling fluid density of a cover and determine method.When this well drilling well finishes, reached the level of 1000 tons of daily output crude oil (amounting to).

Description of drawingsFig. 1 is that the formation pore pressure coefficient of a well is determined figure; Fig. 2 is a gas volume situation map over time in the well in the well kick process; When Fig. 3 is well kick in well gas injection rate variations curve; Fig. 4 is the block diagram that the present invention controls drilling fluid density equipment.

The specific embodiment

At present, no matter be the university textbook or the related tool book of oil drilling, all tell about such principle, promptly the formation pore pressure followed of drilling design determines that method is, according to the density of the highest pore pressure design drilling fluid of a certain bore hole section.Formation pore pressure coefficient of the present invention determines that method is, consider the well control device in the present drilling equipment, various advanced persons' well logging monitoring device, and various ripe already well logging computers determine algorithm etc., can ignore the high pore pressure well of the little minority of proportion Duan Laizuo formation pore pressure gradient and determine.The difference of two kinds of methods can be described for an example.

Example: when certain oil field A well is carried out drilling design, have 1000m well section to descend 13 3/8 " sleeve pipe (17 1/2 " barefoot interval), according to geologic information, wherein the formation pore pressure coefficient of 80m is 1.32, and the pressure coefficient of remainder is 1.22.Two kinds of different definite methods can be arranged, thereby draw different results.

The first, determine method according to tradition, the reservoir pressure coefficient of this well section should be decided to be 1.32.Like this, the drilling fluid density that creeps into use in this well section should be 1.32 (balanced drillings) at least, or 1.34 (conventional drillings).According to common way, be lower than 1.32 drilling fluid if this well section is used, for example strata pressure be defined as 1.22, when the drilling fluid of use 1.22 or 1.24 creeps into, just might when high pressure zone (reservoir pressure coefficient is 1.34), cause blowout, major break down takes place.

The second, according to method of the present invention, the reservoir pressure coefficient of this well section should be decided to be 1.22.Like this, this well section drilling fluid density is 1.22 (balanced drillings), or 1.24 (conventional drillings).(when balanced drilling, drilling fluid density equates with determined formation pore pressure coefficient; When conventional drilling, drilling fluid density is than the high 0.02-0.03 of determined formation pore pressure coefficient.) same, when this well section drilling well, also can run into the partial high pressure layer, yet, can ignore to this high pressure layer when having 3 reasons to make design.

First reason is because the more perfect well control technology of modern drilling well, can forecast in advance and take emergency measures temporarily, such as weighted drilling fluid density, the various well control devices of startup etc., unnecessary fully because the partial high pressure layer of shorter well section, just use highdensity drilling fluid, thereby cause oil layer pollution in whole well section.

Second reason is by the new knowledge to the well kick process mechanism before the blowout in the drilling well.In drilling well, from the blowout sign is arranged, to the actual generation of blowout, it is more much longer than the common imagination of people that it " ferments " time.Specifically in the area, huge port, this time approximately is about 3 times that it is conventionally believed that.This time enough makes the well site engineer take various requisite measures to prevent the generation of blowout, needn't take notice of very much the very little abnormal pressure layer of some accounting example.

After the 3rd reason is based on and re-recognizes the well kick process mechanism, be specifically applied to the definite method of the present invention that is proposed of strata pressure.

This example is referring to table 1.

The formation pore pressure of certain oil field A well of table 1 determines that preface use to determine that formation pore is pressed and determine the drilling well of flat number force coefficient method pressure coefficient drilling well drilling well weighing apparatus of stratum pore design conventional design

Liquid density drilling fluid

The original definite method 1.32 1.34 1.322 usefulness summarys of density 1 usefulness determine that method 1.22 1.24 1.223 the present invention determine definite 1.2217 1.24 1.22 of method 1.228 1.25 1.234 corrections of the present invention

Definite 1.2254 1.24 1.23 of method (look-up table) 5 corrections of the present invention

Method (computing method)

As can be seen from Table 1, determine that with revised formation pore pressure method carries out drilling design, can reduce the density of drilling fluid greatly.Its benefit one is to reduce oil layer pollution, improves exploration effect and crude output; The 2nd, can accelerate bit speed, save drilling cost.In general, drilling fluid density just might " be had one shot " a good oil reservoir if increase by 0.2 for no reason at all; And drilling fluid density just can make the rate of penetration of drill bit improve 3% if can reduce by 0.2.Revised definite method has the effect of " getting twice the result with half the effort " really to drilling engineering.

In the table 1 the 3rd is to draw according to the method that the present invention proposes to 5 results.Description for the well kick process

Use the drilling fluid of certain density to participate in drilling process, one of its free-revving engine is an equilibrium strata pressure, prevents that the gas blowout accident in the drilling well from taking place.The slow eruption process of drilling fluid claims well kick before the blowout, and this is also referred to as gas blowout accident preceding " prelude " takes place.Process mechanism people for well kick study existing last 100 years history.Now majority think, the process of well kick is exactly that promptly the gas ingredients in the interior drilling fluid of well constantly increases, and " liquid vapour mixture " density of the interior unit volume of well is constantly reduced by stratum process of " gas injection " lentamente in well during creeping into.When the minimizing of this density was not enough to the pressure on stratum in the balance well, the overflow that has just produced well head was up to blowout.

In the present invention, the well kick physical process is done following description.

Suppose that a certain drilling depth in going into the well well kick takes place.Can hold drilling fluid and gas this moment in the well total measurement (volume) is n, and wherein liquid volume is s, and gas volume is i.Obviously, begin up to blowout from well kick, s and i are that the function of time t is represented with mathematical formulae:

N=i (t)+s (t) (1) 1 linear the description

First kind of description.When people generally believe well kick for many years in the well increase of gas be the linear function of time, begin from the stratum promptly that gas injection begins in pit shaft, the gas in the well is along with the increase of time increases.Represent with mathematical formulae, be following differential expression: $\frac{\mathrm{di}\left(t\right)}{\mathrm{dt}}=K----\left(2\right)$ (2) formula is solved, just obtains:

I (t)=Kt+c (2) ' c, K is an arbitrary constant, its value will be decided by the condition initial value.

Obviously, following formula thinks that the variation and the time of the interior gas flow of well are linear linear function; Time is long more, and the gas flow increase is many more.And think, from the beginning well kick, the generation of blowout finally, the gas recruitment of its unit interval all is the same.Such well site phenomenon is not explained in this description, and " tendency " when promptly well kick begins be difficult to be caught (air inflow is considerably less in the well), and tolerance moment that blowout begins in the well of back sharply increases.2 non-linear descriptions

At the deficiency of last description, the present invention proposes a new description, and many site engineers use the multi-form approximate statement that also has, second kind of description that Here it is.The Field Force generally recognizes the speed that gas volume increases in the well in the well kick process, is not a constant; Yet be what kind of is non-linear, a lot of people propose different opinions actually.The present invention then directly proposes, and the speed that this moment, gas increased is directly proportional with the volume of gas at that time.

With differential expression with this procedural representation: $\frac{\mathrm{di}\left(t\right)}{\mathrm{dt}}=\mathrm{Ki}\left(t\right)----\left(3\right)$ Solve following formula with the corresponding differential equation solution, must:

i(t)＝e ^kt+c (3)’

As seen from the above equation, the variation of tolerance and be the relation of natural exponential function between the time in the well.This formula has been described such well site phenomenon preferably: promptly when well kick just began, the tolerance that the stratum enters in the well was very little, but along with the time increases, air inflow exponentially ground increases, and in theory, almost can develop into infinity.This formula explained in the scene preferably and gushed " calmness " of beginning, and the huge energy of blowout when taking place.3 one kinds of special non-linear descriptions

The third description is a kind of special non-linear description.This description thinks that gas pours in the speed of well, i.e. the instantaneous recruitment of gas in the pit shaft, and not only with at that time volume of gas is relevant, but also relevant with the actual liquid measure in the pit shaft at that time.Be: $\frac{\mathrm{di}\left(t\right)}{\mathrm{dt}}=\mathrm{Ki}\left(t\right)s\left(t\right)----\left(4\right)$

The basic thought of structure (4) formula is, the speed of injecting gas is not to be directly proportional with gas flow in the well, but with this moment gas flow be directly proportional with the product of liquid measure.That is to say, when gas flow seldom or liquid measure seldom the time, its gas charge velocity is all not very big.Have only when gas flow and liquid measure product when maximum, its gas charge velocity just be a maximum.

Finding the solution (4) the branch equation that declines needs more skill, and attention will be considered (1) formula.End product is: $i\left(t\right)=\frac{n}{1+(\frac{n}{i_0}-1)e^{-\mathrm{knt}}}----\left(5\right)$

(5) i of formula ₀Be constant by the primary condition decision.(5) curve map of formula is seen Fig. 2.From curve, when the well kick process begins or closes to an end, when promptly blowout broke out, the tolerance of injecting in the unit interval in the well was all very little.Here divide 2 discussion:

The firstth, when the well kick process began, the reason that gas injection rate is little was with the 2nd kind of Mathematical Modeling in front at this moment.Particularly, in this moment well gas seldom, liquid is " densification " comparatively speaking comparatively, makes that gas is seamless can " to be bored "; Yet along with the slowly intrusion of gas, bubble increases in the liquid, has not only increased the space for gas continues to invade, and has also objectively reduced the unit density of liquid, and invading in the pit shaft for gas provides condition.

The secondth, when the well kick process finishes, i.e. before blowout was about to break out, this moment, the unit gas injection rate in well still was tending towards reducing gradually.This wherein reason have two:

(1) from physics theory, pit shaft is not simple container, but a long and narrow tubular container that is tending towards " endless " also has the complicated liquid and the handing-over border of container wall in addition; Before blowout begins, because between drilling fluid and the borehole wall, factor affecting such as the gel initial between the drilling fluid molecule, yield value, the head of liquid of drilling fluid itself in addition, make the gases at high pressure on stratum bear one " counter-pressure " (by all directions identity property of gas and fluid pressure transmission), force stratum gas injection rate in pit shaft to reduce.Can suppose that it is " rare " that this high pressure conditions exists a drilling process, otherwise can not imagine that whole drilling process can be in the situation that is about to blowout constantly and carry out.

(2) well kick simulated test in laboratory can prove this point.Add gases at high pressure or water under high pressure to test with pit shaft with a variable delivery pump simulated formation; Put into drilling fluid in the pit shaft.When the pit shaft internal pressure increased, pump was for balance and cylinder pressure, and its discharge capacity obviously reduces.Many in the past laboratories can not get this result when doing similar test, are because these laboratories adopt the high-pressure plunger pump simulated formation to pressurize to pit shaft more, and obvious, this fixed displacement pump is different with the stratum to the principle of pit shaft gas injection.

(3) principle when actual blowout process and the Nature volcanic eruption is roughly the same on the well site.Abroad the mathematical simulation to the volcanic eruption process shows, has individual energy slowly to collect process suddenly before its eruption.And, all can not explain the slowly rapid collection and the eruption suddenly of this energy to first kind or second kind of description of well kick process, the third description then can be explained.The discussion of 4 special non-linear descriptions

About (4) formula mathematical formulae following characteristics are arranged.

The first, the time dependent situation of liquid in the pit shaft in the well kick process.

(4) form that the another kind of branch equation separates that declines is as follows, notes will considering substitution i in finding the solution ₀Relation: $s\left(t\right)=n(1-\frac{1}{1+(\frac{n}{i_0}-1)e^{-\mathrm{knt}}})----\left(6\right)$

Following formula has been represented the interior liquid capacity s (t) of pit shaft situation over time.Obviously owing to (1) formula, the curvilinear figure of (6) formula just in time complements one another with (5) formula.

The second, the maximum rate point of stratum gas injection in pit shaft in the well kick process.

The well kick process in research well site notices naturally when the stratum is to pit shaft gas injection rate maximum, promptly tries to achieve the maximum rate point of gas injection.(5) formula is differentiated to time t, gets following formula: $\frac{\mathrm{di}}{\mathrm{dt}}=\frac{{\mathrm{kn}}^2(\frac{n}{i_0}-1)e^{-\mathrm{knt}}}{{[1+(\frac{n}{i_0}-1)e^{-\mathrm{knt}}]}^2}----\left(7\right)$ When following formula is set up: $\frac{d^{2}i}{d^2{t}_{t=0}}=0----{\left(7\right)}^{\′}$

Fig. 3 has described the general shape of (7) formulas.As seen from the figure, when following formula reaches peak-peak, i.e. t ₀Constantly, stratum gas injection speed in pit shaft reaches peak.Be not difficult to draw by the differential extremum principle: $t_0=\frac{\ln (\frac{n}{i_0}-1)}{\mathrm{kn}}----\left(8\right)$ The graph curve of 5 three kinds of well kick explanations relatively

According to (2) formula, (3) formula and (4) formula, all the same geology block of substitution, the geology on same stratum and the initial condition of gas solve constant i ₀And k, just can draw Fig. 2.As can be seen from Figure, be research object with the same well, with 3 kinds of different explanations, it is by beginning well kick (the blowout sign is promptly arranged), and to the time span that blowout takes place, first kind of interpretation time is the shortest at interval, second kind of interpretation time taken second place at interval, and the third interpretation time is the longest at interval.

The present invention before the probing of certain well, the geological conditions parameter tentative calculation of this well of substitution once, gained the results are shown in Table 2.

The preface as a result of 3 kinds of explanations of table 2 is used and is determined that method differential equation mathematical formulae begins to the blowout time takes place from well kick, (during trumpet) 1 linear explanation, (2) formula, (2) ' formula non-linear explanation in about 3 hours 2, (3) formula, (3) ' formula special non-linear explanation in about 4 hours 3, (4) formula, (5) formula is no less than 6 hours

In fact in above-mentioned well location, drilling engineer and mud engineer's empirical data is to find that well kick is about 2 hours to the time of actual blowout before.

The proposition of the 3rd kind of explanation and application have 2 layers of meaning:

The one, determine to provide rationale for improving reservoir pressure coefficient, promptly the stratum well kick is process of " very long ", does not resemble original people contemplated " of short duration " so, certainly has the enough time to go to handle the control blowout.

The 2nd, also have higher requirement for work such as well logging, well controls.Before above-mentioned well spuds in, the present invention proposes, because the appearance of this regional blowout sign is no less than 6 hours to time of actual blowout, well logging team should strive making forecast in blowout before 6 hours, every gas blowout accident that causes because there not being forecast in time, Ying Youlu and team are responsible for.This determines under the method at new strata pressure for on-the-spot drilling crew, uses low density drilling fluid to creep into, and decomposes the gas blowout accident responsibility, alleviates the operating personnel's of drilling team mental burden; Be well logging work also simultaneously, proposed new target and requirement.The method of stressor layer definitely of the present invention

For above-mentioned example 12 problems can be proposed, the one, when accounting for the barefoot interval ratio of being crept into, certain high pressure zone length on stratum is how many times, can ignore the existence of this high pressure zone? the 2nd, this moment, how many times high pressure zone and low pressure layer ratio were, even the high pressure zone ratio not quite can not be ignored? the 3rd, after ignoring the minority high pressure zone, how to make new determined value, and in determined value, consider the influence of this high pressure zone? 1 original method is the cover half type really

If the formation pore pressure coefficient value of determined a certain barefoot interval is P, the length of this barefoot interval is L, then determines to be method with mathematical notation in the past:

P＝ξ _max (9)

ξ wherein _Max=Max (ξ ₁, ξ ₂, ξ ₃... ξ _i... ξ _n), ξ _iBe the formation pore pressure coefficient on this bore hole section i stratum, n is stratum sum in the bore hole section for this reason.The relation of 2 definite methods of the present invention and original method

The pressure coefficient expression formula of definite method of the present invention is: $P=\frac{{\&Integral;}_{l_1}^{{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A0113101900321.png"\; state="\{\{state\}\}">l</figure-callout>}}_2}\mathrm{\&xi;dl}}{L}----\left(10\right)$ L wherein ₁With l ₂Initial and the beginning stop bit of bore hole section is put for this reason, has

L＝l ₂-l ₁ (11)

(10) formula is done a replacement:

ξ＝ξ _max (12)

The gained result is (9), i.e. original method of determining about reservoir pressure coefficient.So according to this method, the oil field was prolonged the reservoir pressure coefficient of usefulness originally and determined method, but be a kind of special case of (10) formula.Definite method under the 3 discontinuous conditions

If consider that (10) usually are the segmentation discontinuous functions in integrating range, then (10) formula can be rewritten as: $P=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&xi;}}_i{l}_i}{L}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{l_i}{L}{\mathrm{\&xi;}}_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i----\left(13\right)$

β wherein _I=l _i/ L;

Find out β easily _iThe actual weighted factor that is the reservoir pressure coefficient of i layer to last determined value P perhaps claims contribution coefficient.

First kind of correction (look-up table) of 4 pairs of definite methods

The invention provides a kind of look-up method, come determining that the result revises.Look-up table and the computing method of introducing later all are that the strata pressure that various sources obtain is determined initial data evaluation.Geological Engineering personnel are carrying out pressure coefficient when determining, the basic data that all will get according to various technological means usually, and as to two dimension or 3-d seismic exploration data that will the drilling well area, institute have finished the drilling well neighbouring area the real drilling collection data of well etc.The reliability of these data, or all say accuracy, to determining that the result has very big influence.

(13) formula is done distortion slightly becomes following formula: $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&lambda;}}_i{\mathrm{\&omega;}}_i{\mathrm{\&xi;}}_i----\left(14\right)$

λ in the formula _iBe the probability coefficent of i formation pressure data data source accuracy rate, ω _iIt is the fault block situation coefficient of i layer.λ _iObtain and see Table 3.ω _iObtain and see Table 4.

Table 3 data source coefficient lambda _iThe list of values preface uses the method for determining to obtain formation pressure data data mode λ _iValue number 1 ξ _i＜=Ω 12 ξ _I＞Ω is with block offset well 0.983 ξ _I＞Ω 3-D seismics data 0.954 ξ _I＞Ω 2-d seismic data 0.93

Selecting λ _iValue, ξ _IDuring＞Ω,, then can from table 3, choose a maximum value, as λ if can obtain above-mentioned 2 kinds or 3 kinds of data simultaneously _iValue.

Table 4 tomography situation coefficient ω _iThe list of values preface is used and is determined method drilling well location fault block situation ω _iValue number 1 ξ _i＜=Ω 12 ξ _I＞Ω fault block is few, more complete 0.993 ξ in oil field _I＞Ω fault-block oilfield 0.96

Selecting ω _iValue, ξ _IDuring＞Ω,, then can from table 4, choose a maximum value, as ω if can obtain above-mentioned a kind or 2 kinds of data simultaneously _iValue.Ω value in table 3 and the table 4 is: $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{l_i}{L}{\mathrm{\&xi;}}_i----\left(15\right)$ Second kind of correction (computing method) of 5 pairs of definite methods

The invention provides another method, revise definite result with direct calculation method.The advantage of look-up table, main on-the-spot for convenience the use, but shortcoming is the difference of having ignored between the service condition.Computing method of the present invention can utilize the achieved reliability probability of each oil field Various types of data to determine obviously have better reasonability.

The first, the data processing intent.In general, the data of using various technological means to obtain for example utilize two dimension or 3-D seismics to obtain the formation pore pressure specified data, utilize designed well completed offset well data on every side, can draw the probable value of its accuracy or reliability.

The second, the data sample source.With the data information in a certain data acquisition unit and certain model device several years is sample, for example calculate the 3-D seismics data and determine the reliability of Abnormal Formation Pressure data, just the data of being gathered with certain seismic prospecting company and certain model 3-D seismics instrument thereof are as data sample.By the real data contrast of drilling well, determine the accuracy of its original survey data.Simply say, only do the checking of " meeting " and " not meeting ".It is considered herein that this is " independent event " probability. ${\mathrm{\&eta;}}_i=\frac{m}{n}----\left(16\right)$

η wherein _iBe the reliable probability of this data acquisition, n is a data increment sum, and m determines accurately or accurate increment number.In general, data increment sum n should not be less than 200.When the well of stressor layer has a plurality of Data Source definitely, just with the highest the sort of Data Source of reliability as reliable probability.

The 3rd, data are handled.In the present invention, obtain the purpose of Data Source reliable probability, just to determine that in order estimating in the pressure coefficient, those are higher than the reliability of the above coefficient value of weighted average, or to claim confidence level, so following formula is arranged: $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i----\left(17\right)$ $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&tau;}}_i----\left(18\right)$ Wherein: τ _i=ξ _iWork as ξ _iDuring≤Ω

τ _i=Ω+(ξ _i-Ω) * η _iWork as ξ _iDuring＞Ω

More than be exactly the 2nd kind of modification method of the present invention (computing method).

Embodiment

Embodiment 1:

Condition is with aforementioned example.(13) formula in the known conditions substitution is calculated, promptly got the 3rd result of table 1. $P=\frac{920}{1000}\&times;1.22+\frac{80}{1000}\&times;1.32=1.228----\left(19\right)$

Embodiment 2:

Condition is with aforementioned example.Supplementary condition well for this reason is in fault-block oilfield, and given data derives from the 3-D seismics interpretation data.With known conditions substitution (14) formula, the 4th result in must table 1. $P=\frac{920}{1000}\&times;1.22+\frac{80}{1000}\&times;1.32\&times;0.98\&times;0.96=1.2217----\left(20\right)$

Embodiment 3:

Condition is with embodiment 2.Supplementary condition according to (16) formula, is got 200 increments for carrying out the sample fail-safe analysis to determining that basic data is originated, and is 65% through actual well drilled checking reliable probability.With known conditions substitution (17) formula and (18) formula, the 5th result in must table 1.

Ω＝1.228 $P=\frac{920}{1000}\&times;1.22+\frac{80}{1000}\&times;[1.228+(1.32-1.228)\&times;0.65]=1.2254----\left(21\right)$

The above results is discussed.

The first, the result of calculation of above-mentioned example and embodiment 1 relatively.Result of calculation of utilization (13) formula and the 2nd result in the table 1, promptly the summary calculated value is more or less the same (is 1.22 with summary method determined value), and error is less than 0.7%; Not not strictly speaking, determine coefficient mostly more than 1.0 if consider pressure, then two results' relative error also is no more than 4%, illustrates from engineering to use upward, and two kinds of method gained results are basic identical.

The second, the comparison of embodiment 2 and embodiment 1 and above-mentioned example result of calculation.The computational methods of utilization (14) formula, the gained result is the 4th kind of result in the table 2, and is then very nearly the same with the result of sketched approaches.

Below, contrast Fig. 4 illustrates that the present invention controls the block diagram of drilling fluid density equipment.

As shown in Figure 4, the equipment of control drilling fluid density of the present invention comprises with lower device: basic drilling parameter input unit 1, and it is used to import the length L of barefoot interval; Drilling parameter automatic detection device 2, it is used to measure the original position l of each well section ₁, final position l ₂Length l with each well section _i, and the formation pore pressure coefficient ξ of each section of drilling well _iThe special-purpose Industrial Control Computer 3 of drilling well, its input links to each other with described drilling parameter self-operated measuring unit 2 with described basic drilling parameter input unit 1, is used for determining the formation pore pressure FACTOR P and the drilling fluid density of drilling well, and output drilling fluid control signal; Controller 6 and change drilling fluid density device 8 automatically, controller 6 and change drilling fluid density device 8 automatically constituted the drilling fluid density control device, be used for according to described drilling fluid control signal control drilling fluid density.

In addition, the equipment of control drilling fluid density of the present invention also comprises the 1st memory and the 2nd memory, and the control program that the special-purpose Industrial Control Computer 3 of the 1st memory storage drilling well can be carried out is so that the input of the automatic detection of control drilling parameter, basic drilling parameter.Certainly, the special-purpose Industrial Control Computer 3 of drilling well also can constitute the device of the input of the automatic detection of special-purpose control drilling parameter, basic drilling parameter with the design of the 1st memory together.This design is a kind of general knowledge to those skilled in the art, it be not explained in detail at this.

The 2nd memory is used to store the program of the formation pore pressure FACTOR P of various definite drilling well, and produces and the program of output drilling fluid control signal.Equally, special-purpose Industrial Control Computer 3 also can constitute a kind of device of formation pore pressure FACTOR P, generation and output drilling fluid control signal of definite drilling well of special use with the design of the 2nd memory together.

Basic drilling parameter input unit 1 can adopt conventional device, as keyboard, optical signal, wireless signal etc., so that the length L of input barefoot interval.The automatic detection device 2 of drilling parameter also can adopt conventional checkout gear, and as length measuring sensor, the pressure coefficient measuring transducer is so that measure the original position l of each well section ₁, final position l ₂Length l with each well section _i, and the formation pore pressure coefficient ξ of each section of drilling well _I

In the 1st kind of program or device of the formation pore pressure FACTOR P of determining drilling well, according to following formula $P=\frac{{\&Integral;}_{l_1}^{{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A0113101900321.png"\; state="\{\{state\}\}">l</figure-callout>}}_2}\mathrm{\&xi;dl}}{L}$ Determine the formation pore pressure FACTOR P of drilling well.

In the 2nd kind of program or device of the formation pore pressure FACTOR P of determining drilling well, according to following formula $P=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&xi;}}_i{l}_i}{L}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\frac{l_i}{L}\mathrm{\&xi;}}_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i$ Determine the formation pore pressure FACTOR P of drilling well.

In the 3rd kind of program or device of the formation pore pressure FACTOR P of determining drilling well, according to following formula $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&lambda;}}_i{\mathrm{\&omega;}}_i{\mathrm{\&xi;}}_i$ β _I=l _i/ L determines the formation pore pressure FACTOR P of drilling well, wherein in following formula, and ω _iValue determine according to following formula: $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{l_i}{L}{\mathrm{\&xi;}}_i$

Work as ξ _iDuring＜=Ω, ω _i=1;

Work as ξ _IDuring＞Ω, ω _i=0.99; Perhaps

Work as ξ _IDuring＞Ω, ω _i=0.96; λ _iValue decide according to following mode:

Work as ξ _iDuring＜=Ω, λ _i=1;

Work as ξ _IDuring＞Ω, λ _i=0.98; Perhaps

Work as ξ _IDuring＞Ω, λ _i=0.95; Perhaps

Work as ξ _IDuring＞Ω, λ _i=0.93.

In the 4th kind of program or device of the formation pore pressure FACTOR P of determining drilling well, according to following formula $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&tau;}}_i$ $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i$ β _I＝l _i/L ${\mathrm{\&eta;}}_i=\frac{m}{n}$ Determine the formation pore pressure FACTOR P of drilling well, wherein: τ _i=ξ _iWork as ξ _iDuring≤Ω;

τ _i=Ω+(ξ _i-Ω) * η _iWork as ξ _iDuring＞Ω;

N is a data increment sum, and m is the accurate or accurate increment number of determining.

In addition, also store the program of determining drilling fluid density in described the 2nd memory, the special-purpose Industrial Control Computer 3 of drilling well is carried out this and is determined the program of drilling fluid density, makes that drilling fluid density is defined as equating with the formation pore pressure coefficient of determined drilling well when balanced drilling; When conventional drilling, drilling fluid density is defined as the high 0.02-0.03 of formation pore pressure coefficient than determined drilling well.In addition, the 2nd memory can also be designed to one with the special-purpose Industrial Control Computer 3 of drilling well, forms the device of special-purpose definite drilling fluid density.

The special-purpose controller 3 of drilling well is exported corresponding drilling fluid control signal according to the drilling fluid density of having determined, and changes drilling fluid density device 8 automatically by controller 6 controls.Automatically change drilling fluid density device 8 by changing the composition of drilling fluid, perhaps change and remove native addition, change drilling fluid density.This automatic change drilling fluid density device 8 also is an one type of prior art syringe, also is not described in detail at this.

In addition, the equipment of control drilling fluid density of the present invention also comprises output report and curve map device, is used to export the formation pore pressure FACTOR P and the drilling fluid density of determined drilling well, and corresponding curve map.The present invention is in the application of dark 7 wells of plate

In April, 1998, the present invention once used revised formation pore pressure to determine that method carries out the geological design and the engineering design of this well when the dark 7 well drilling design of plate.Now briefly introduce as follows.

Before drilling engineering design, relevant department has carried out the geological design of this well, and wherein the formation pore pressure coefficient determines that figure is as Fig. 1.Dotted line among the figure has marked and has utilized original formation pore pressure coefficient to determine the curve map that method is drawn.Find out that therefrom the determined value of original formation pore pressure coefficient is higher, this can make the density of used drilling fluid in the following drilling well higher.The present inventor has had access to the data of this well drilled well on every side again, and phase closing well situation sees Table 5.

It can be seen from the table, at the offset well of A---in the B5-1 well stratum, 2 abnormal pressure layers are arranged, i.e. the table 5 No. 5 floor and No. 7 floor.One of them is positioned at well depth 3369m to 3380m well section, and another is to be positioned at 3729m to 3745m well section.These 2 stratum are thick about 11m and 16m respectively, and reservoir pressure coefficient is 1.33 and 1.31.Make a general survey of the whole geological condition of dark 7 wells of plate, if do not consider this 2 layer positions, its reservoir pressure coefficient is all below 1.25, and its average is about 1.09.Determined method according to former common reservoir pressure coefficient, then must consider these 2 layer positions, in other words must be with the pressure coefficient of these 2 layers pressure coefficient value as whole bore hole section (2900m is to 3900m), the pore pressure determined value of this well section is 1.31 like this.Obviously, under this definite result, the density of drilling fluid is at least 1.31 in the drilling well.

The geological design that remodifies with definite method of the present invention.Solid line among Fig. 1 is amended reservoir pressure coefficient curve.By definite method of revising, can ignore in No. 5 stratum and No. 7 stratum in the table 5, and its reason as previously mentioned.The reservoir pressure coefficient determined value of this well section just reduces to 1.25 as a result, and the drilling fluid density in the actual well drilled has also lowered significantly afterwards naturally.

The drilling practice of dark 7 wells of plate in 1998 proves, presses the reduction significantly of determined value at formation pore, brought the vast scale of drilling fluid density to reduce, thereby significantly reduced in the drilling process drilling fluid to the degree of contamination of oil reservoir.This well up to the 5000m finishing drilling, has all found oil gas in considerable part well section from 1750m.Wherein comparatively typical 1750m and 3700m, and 4000m is with sub-surface.

Use definite method and apparatus of the present invention, fundamentally provide possibility, also just increased new method for improving newly developed area and old liberated area oil field prospecting and development effectiveness for reducing drilling fluid density.

(1) method and apparatus of the present invention all is effective in the drilling practice of oil exploration and development well; This method alleviates the degree of contamination of drilling process to oil reservoir for fundamentally reducing drilling fluid density, and accelerates bit speed, reduces drilling cost, and obvious effects is all arranged; Follow huge economic benefit on a large scale after the popularization;

(2) method and apparatus of the present invention has improved the formation pore pressure gradient and has determined precision, for the enforcement of conventional drilling, quasi-equilibrium drilling well, balanced drilling, under balance pressure drilling provides the necessary data that define; Also be various types of drilling well forms, critical basic data is provided;

(3) use of the present invention is simple; Can improve drilling results or oil recovery amount largely not increasing the red cent investment condition.

The dark 26 well 3602-3633 m 1.12 of the dark 5-1 well of dark 5 well 2451-2460 m 1.133 plates of the dark 5 well 2596-2627 m of table 5 Banshen 7 Well offset well strata pressure situation sequence number pound sign well fragment position (m) formation pore pressure coefficient 1 plate 0.932 plate dark 5-1 well 3923-3936 m 1.224 plates dark 5-1 well 3800-3829 m 1.205 plates dark 5-1 well 3729-3745 m 1.316 plates dark 5-1 well 3698-3745 m 1.257 plates 3369-3380 m 1.338 plates, 851 well 2582-2596 m, 0.949 plate, 851 well 3703-3721 m, 1.0510 plates, 855 well 2765-2776 m, 1.0111 plates dark 25 well 3851-3870 m 1.2312 plates

Claims (13)

1, a kind of equipment of controlling drilling fluid density is characterized in that comprising with lower device:

Basic drilling parameter input unit (1) is used to import the length (L) of barefoot interval;

Drilling parameter automatic detection device (2) is used to measure the original position (l of each well section ₁), final position (l ₂) and the length (l of each well section _i), and the formation pore pressure coefficient (ξ of each section of drilling well _i);

Drilling well controller (3), its input links to each other with described drilling parameter self-operated measuring unit (2) with described basic drilling parameter input unit (1), is used for determining the formation pore pressure coefficient (P) and the drilling fluid density of drilling well, and output drilling fluid control signal;

Drilling fluid density control device (6,8) is used for according to described drilling fluid control signal control drilling fluid density.

2, equipment according to claim 1 is characterized in that, described drilling well controller (3) comprises that the formation pore pressure coefficient determines device, is used for determining the formation pore pressure coefficient (P) of drilling well.

3, equipment according to claim 2 is characterized in that, described formation pore pressure coefficient determines that device comprises according to following formula $P=\frac{{\&Integral;}_{l_1}^{l_2}\mathrm{\&xi;dl}}{L}$ Determine the device of the formation pore pressure coefficient of drilling well.

4, equipment according to claim 2 is characterized in that, described formation pore pressure coefficient determines that device comprises according to following formula $P=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&xi;}}_i{l}_i}{L}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{l_i}{L}{\mathrm{\&xi;}}_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i$ Determine the device of the formation pore pressure coefficient of drilling well.

5, equipment according to claim 2 is characterized in that, described formation pore pressure coefficient determines that device comprises according to following formula $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&lambda;}}_i{\mathrm{\&omega;}}_i{\mathrm{\&xi;}}_i$ β _I=l _i/ L determines the device of the formation pore pressure coefficient of drilling well, wherein in following formula, and ω _iValue determine according to following formula: $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{l_i}{L}{\mathrm{\&xi;}}_i$

Work as ξ _iDuring＜=Ω, ω _i=1;

Work as ξ _IDuring＞Ω, ω _i=0.99; Perhaps

Work as ξ _IDuring＞Ω, ω _i=0.96; λ _iValue decide according to following mode:

Work as ξ _iDuring＜=Ω, λ _i=1;

Work as ξ _IDuring＞Ω, λ _i=0.98; Perhaps

Work as ξ _IDuring＞Ω, λ _i=0.95; Perhaps

Work as ξ _IDuring＞Ω, λ _i=0.93.

6, equipment according to claim 2 is characterized in that, described formation pore pressure coefficient determines that device comprises according to following formula $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&tau;}}_i$ $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i$ ${\mathrm{\&eta;}}_i=\frac{m}{n}$ β _I=l _i/ L determines the device of the formation pore pressure coefficient of drilling well, wherein: τ _i=ξ _iWork as ξ _iDuring≤Ω;

τ _i=Ω+(ξ _i-Ω) * η _iWork as ξ _iDuring＞Ω;

N is a data increment sum, and m is the accurate or accurate increment number of determining.

7, according to 1 described equipment among the claim 1-6, it is characterized in that, described drilling well controller (3) further comprises the device of determining drilling fluid density, and when balanced drilling, drilling fluid density is defined as equating with the formation pore pressure coefficient of determined drilling well; When conventional drilling, drilling fluid density is defined as the high 0.02-0.03 of formation pore pressure coefficient than determined drilling well.

8, a kind of method of definite drilling fluid density is characterized in that may further comprise the steps: (1) measures the formation pore pressure coefficient (ξ of each section of drilling well _i); (2) length (L) of measurement barefoot interval; (3) measure the original position (l of each well section ₁), final position (l ₂) and the length (l of each well section _i); (4) determine the formation pore pressure coefficient (P) of drilling well; (5) determine drilling fluid density.

9, method according to Claim 8 is characterized in that, the step of the formation pore pressure coefficient of described definite drilling well comprises according to following formula $P=\frac{{\&Integral;}_{l_1}^{l_2}\mathrm{\&xi;dl}}{L}$ Determine the step of the formation pore pressure coefficient of drilling well.

10, method according to Claim 8 is characterized in that, the step of the formation pore pressure coefficient of described definite drilling well comprises according to following formula $P=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&xi;}}_i{l}_i}{L}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{l_i}{L}{\mathrm{\&xi;}}_i=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i$ Determine the step of the formation pore pressure coefficient of drilling well.

11, method according to Claim 8 is characterized in that, the step of the formation pore pressure coefficient of described definite drilling well comprises according to following formula $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&lambda;}}_i{\mathrm{\&omega;}}_i{\mathrm{\&xi;}}_i$ β _I=l _i/ L determines the step of the formation pore pressure coefficient of drilling well, and wherein in following formula, the value of ω i is determined according to following formula: $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{l_i}{L}{\mathrm{\&xi;}}_i$ Work as ξ _iDuring＜=Ω, ω _i=1; Work as ξ _IDuring＞Ω, ω _i=0.99; Perhaps work as ξ _IDuring＞Ω, ω _i=0.96; λ _iValue decide according to following mode:

Work as ξ _iDuring＜=Ω, λ _i=1;

Work as ξ _IDuring＞Ω, λ _i=0.98; Perhaps

Work as ξ _IDuring＞Ω, λ _i=0.95; Perhaps

Work as ξ _IDuring＞Ω, λ _i=0.93.

12, method according to Claim 8 is characterized in that, the step of the formation pore pressure coefficient of described definite drilling well comprises according to following formula $P=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&tau;}}_i$ $\mathrm{\&Omega;}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_i{\mathrm{\&xi;}}_i$ ${\mathrm{\&eta;}}_i=\frac{m}{n}$ β _I=l _i/ L determines the step of the formation pore pressure coefficient of drilling well, wherein: τ _i=ξ _iWork as ξ _iDuring≤Ω;

τ _i=Ω+(ξ _i-Ω) * η _iWork as ξ _iDuring＞Ω;

N is a data increment sum, and m is the accurate or accurate increment number of determining.

13, according to Claim 81 described method-12 is characterized in that the step of described definite drilling fluid density further may further comprise the steps:

When balanced drilling, drilling fluid density is defined as equating with the formation pore pressure coefficient of determined drilling well; When conventional drilling, drilling fluid density is defined as the high 0.02-0.03 of formation pore pressure coefficient than determined drilling well.

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