CN115015043A - A kind of detection method of low-density solid phase content of oil-based drilling fluid - Google Patents

Abstract

The invention relates to a method for detecting the low-density solid content of an oil-based drilling fluid, which belongs to the field of oilfield chemistry of the petroleum industry and comprises the steps of taking an oil-based drilling fluid sample and uniformly stirring the oil-based drilling fluid sample; measuring the volumes of oil and water in the drilling fluid by adopting a distillation method, and calculating to obtain the volume fractions of the oil, the water and a solid phase; crushing the solid phase obtained after distillation by using a crusher, and drying and storing; preparing a plurality of portions of diiodomethane separation liquid with different densities for later use; sequentially using diiodomethane separation liquid with the density from low to high, and forming samples with different densities by a floating and settling separation method for the solid phase of the drilling fluid; weighing the mass of each partial sample, and calculating the volume of each partial sample; and rejecting the sample separation volume which does not belong to the density range of the low-density solid phase according to the density range of the low-density solid phase in the drilling fluid. On the basis of measuring the solid phase content by a distillation method, the invention adopts the separation liquid to separate and remove the materials which do not belong to the low-density solid phase, thereby greatly improving the measurement accuracy.

Description

A kind of detection method of low-density solid phase content of oil-based drilling fluid

technical field

The invention relates to a method for detecting the low-density solid phase content of an oil-based drilling fluid, belonging to the field of oilfield chemistry in the petroleum industry.

Background technique

With the large-scale development of unconventional oil and gas resources such as shale oil and shale gas, the problem of wellbore instability in shale formations has become more and more serious. widely used.

As an important index, the solid phase content of oil-based drilling fluids has a great influence on the rheology and filtration performance of drilling fluids. According to the difference of solid phase density, the solid phase in oil-based drilling fluid can be divided into two types: high-density solid phase and low-density solid phase: barite belongs to high-density solid phase, and solid phases other than barite include organic soil , calcium oxide, fluid loss reducer, drilling cuttings, etc. belong to the low-density solid phase.

With the increase in the number of reuses of oil-based drilling fluid, the drilling cuttings in the drilling fluid continue to increase, especially when the large particles become small particles after repeated grinding, the ability of solids control equipment to remove small particles is weakened, which makes the drilling fluid The low-density solids content of the medium increases rapidly. When the low-density solid content is too large, the viscosity and flow resistance of the drilling fluid will increase, resulting in a decrease in the mechanical speed; in addition, high low-density solid content can easily lead to poor quality of the mud cake, leading to support pressure, sticking, etc. Downhole complex situation. Therefore, in the drilling process, not only the solid phase content of oil-based drilling fluids, but also the low-density solid phase content should be paid close attention.

Currently, the way to evaluate the low-density solids content of drilling fluids relies on distillation. According to the national standard GB/T16783.2-2012 "Field Test of Drilling Fluids in Oil and Gas Industry Part 2: Oil-Based Drilling Fluids", the volume of low-density solid phase in oil-based drilling fluid is equal to the volume difference between the total suspended solid phase and the weighted material ( The total suspended solid phase refers to the insoluble solid phase in the oil-based drilling fluid, which can be divided into two categories according to the density: one is the weighted material used to adjust the density of the drilling fluid, such as barite, iron ore powder, manganese ore powder, etc. 4.0g/cm ³ ; one is low-density solid phase, such as drill cuttings, inferior soil, gravel, etc.).

The average density of the total suspended solid phase is shown in formula (1).

In the formula, ρ _sol is the average density of suspended solid phase, g/cm ³ ; ρ _s is the density of drilling fluid, g/cm ³ ; θ _O is the volume percentage of oil, %; ρ _O is the density of oil, g/cm ³ ; θ _B is the volume percentage of brine in drilling fluid, %, where brine is a complex of water and dissolved salt; ρ _B is the density of brine, g/cm ³ ; θ _sol is the volume percentage of corrected solid phase.

The volume percentage of the weighted material is shown in formula (2):

In the formula, θ _wm is the volume percentage of the weighted material in the total suspended solid phase, %; ρ _wm is the average density of the weighted material, g/cm ³ ; ρ _lg is the density of the low-density solid phase, g/cm ³ .

The volume percentage of the low-density solid phase is shown in formula (3):

θ _lg = θ _sol - θ _wm (3)

In the formula, θ _lg is the volume percentage of the low-density solid phase in the total suspended solid phase, %.

In the national standard GB/T 16783.2-2012 "Field Test of Drilling Fluids in Oil and Gas Industry Part 2: Oil-Based Drilling Fluids", the density of the low-density solid phase is calculated according to 2.65g/ ^cm3 (that is, the density of the low-density solid phase ρ _lg Take 2.65g/cm ³ ), but because the density of drilling fluid varies, and oil-based drilling fluid usually also contains other low-density solid phases such as fluid loss reducer, organic soil, calcium oxide, etc. The density of the density solid phase is usually not equal to 2.65 g/cm ³ , causing the final calculated low density solid phase content to deviate from the actual low density solid phase content.

SUMMARY OF THE INVENTION

Aiming at the problem of poor testing accuracy of low-density solid phase content in oil-based drilling fluids in the prior art, the present invention provides a new method for detecting low-density solid phase content in oil-based drilling fluids. On the basis of the content, the separation liquid is used to separate and remove the materials that do not belong to the low-density solid phase, which greatly improves the measurement accuracy.

The present invention adopts following technical scheme:

A method for detecting low-density solid phase content of oil-based drilling fluid, comprising the following steps:

(1) Take oil-based drilling fluid samples and stir them evenly;

(2) Transfer a certain amount of drilling fluid samples to the sample cup of the drilling fluid oil-water solid phase content device, measure the volume of oil and water in the drilling fluid by distillation, and use the measured oil and water volumes, as well as the original drilling fluid. The volume of the liquid sample is calculated to obtain the volume fraction of oil, water and solid phase;

(3) the solid phase obtained after distillation is pulverized by a pulverizer and then dried and preserved;

(4) Prepare a number of diiodomethane sorting solutions with different densities for use, including the first density diiodomethane sorting solution, the second density diiodomethane sorting solution, ..., the Nth density diiodomethane sorting solution liquid, N≥3; the larger the N, the closer the calculation result is to the accurate value;

(5) Use the diiodomethane sorting fluid with the density from low to high in turn, and separate the solid phase of the drilling fluid by the method of floating and sinking to form different densities. The specific:

1, the solid phase obtained in step (3) is poured into the centrifugal tank, the first density diiodomethane sorting solution is added, and centrifugation is carried out after fully stirring, dispersing, and the upper layer suspension after the centrifugation is subjected to suction filtration, and the suction pump is turned on. Switch on and off, slowly pour the solid-liquid mixture, after filtering, first remove the suction filter bottle connection, then turn off the suction pump, and dry in the oven to obtain a sub-sample with a density less than the first density;

II. The second density diiodomethane sorting solution is poured into the centrifuge tank and mixed with the lower sediment after the centrifugation of the previous step, fully stirred and dispersed, and then centrifuged, and the centrifuged upper suspension is subjected to suction filtration, in an oven After drying, a sample with a density between the first density and the second density is obtained, and the filtrate is replenished and recycled;

III. Repeat step II continuously until the N-th density diiodomethane sorting solution is poured into the centrifuge tank and mixed with the lower sediment after the centrifugation in the previous step, fully stirred and dispersed, and then centrifuged, and the centrifuged upper suspension is centrifuged. Suction filtration, drying in an oven to obtain a sample with a density between the Nth density and the N-1th density, and at the same time, filter, wash and dry the lower sediment after the centrifugation to obtain a sample with a density greater than the Nth density; So far, N+1 subsamples are obtained;

The present invention separates the solid phase of the drilling fluid by means of continuous sorting and adopts sorting fluids with different densities from low to high, thereby obtaining solid phase samples of different densities in turn.

(6) weighing the quality of each sub-sample after drying to constant weight, and calculating the volume of each sub-sample;

(7) According to the density range of the low-density solid phase in the drilling fluid, the sub-sample volume that does not belong to the density range of the low-density solid phase is eliminated.

The present invention adopts diiodomethane sorting liquid for sorting, wherein because the density of diiodomethane (3.3g/cm ³ ) is usually greater than most of the solid phases except barite in the oil-based drilling fluid, diiodomethane is used for sorting. Methane sorting liquid can separate barite from other solid phases. Moreover, since the solid phase contains hydrophilic minerals such as clay, the use of organic solvents can avoid the disadvantage of low apparent density caused by clay hydration.

Preferably, in step (2), according to the national standard GB/T 16783.2-2012 "oil and gas industry drilling fluid field test Part 2: oil-based drilling fluid" described in the determination of oil, water and solid content by distillation method Determination procedure to determine the volume of oil and water;

Calculate the volume fraction of oil in a drilling fluid sample:

in:

为油占样品总体积的百分数，％；

is the percentage of oil in the total volume of the sample, %;

V _o is the volume of oil in milliliters (mL);

V _s is the volume of the drilling fluid sample, in milliliters (mL);

Calculate the volume of water in the drilling fluid sample:

in:

为水占样品总体积的百分数，％；

is the percentage of water in the total volume of the sample, %;

_Vw is the volume of water in milliliters (mL);

V _s is the volume of the drilling fluid sample, in milliliters (mL);

The solid phase volume fraction is:

in:

为蒸馏固相占样品总体积的百分数，％。

It is the percentage of the total volume of the sample in the distillation solid phase, %.

Preferably, in step (4), the densities of several portions of the diiodomethane separation solution are in an arithmetic progression from low to high.

Preferably, the density of the low-density solid phase in the drilling fluid is in the range of 2.0-3.2 g/cm ³ . Considering that the density of the low-density solid phase in the drilling fluid is in the range of 2.0-3.2 g/cm ³ , the separation fluid has a density of 2.0-3.2 g/cm 3 . The density range is 1.8-3.2 g/cm ³ , that is, the first density of diiodomethane sorting is 1.8 g/cm ³ , and the Nth density is 3.2 g/cm ³ .

Preferably, in step (4), the process of preparing the diiodomethane sorting solution is:

Take a certain mass of chloroform and add it to diiodomethane, transfer it to an airtight container and shake it up. The density of the prepared diiodomethane sorting solution can be calculated from the following formula:

Wherein, M _chloroform is the mass of chloroform, and the unit is g;

M _{diiodomethane} is the mass of diiodomethane, in g;

V _{sorting liquid} is the volume of sorting liquid, the unit is mL;

ρ _{sorting liquid} is the density of sorting liquid, and the unit is g/cm ³ .

Preferably, the density of the diiodomethane separation solution is preferably 1.8g/cm ³ , 2.0g/cm ³ , 2.2g/cm ³ , 2.4g/cm ³ , 2.6g/cm ³ , 2.8g/cm ³ , 3.0 g/cm ³ and 3.2g/cm ³ , the sub-sample densities obtained in turn are ρ≤1.8g/cm ³ , 1.8g/cm ³ <ρ≤2.0g/cm ³ , 2.0g/cm ³ <ρ≤2.2g /cm ³ , 2.2g/cm ³ <ρ≤2.4g/cm ³ , 2.4g/cm ³ <ρ≤2.6g/cm ³ , 2.6g/cm ³ <ρ≤2.8g/cm ³ , 2.8g/cm ³ <ρ≤3.0g/cm ³ , 3.0g/cm ³ <ρ≤3.2g/cm ³ and ρ>3.2g/cm ³ , in step (7), ρ≤1.8g/cm ³ , 1.8g/cm The sub-sample volumes with cm ³ <ρ≤2.0g/cm ³ and ρ>3.2g/cm ³ are excluded, and the volume of low-density solid phase does not need to be included.

Preferably, in step (6), the volume of each sample is:

in:

V _i is the i-th subsample volume, in cubic centimeters (cm ³ );

M _i is the mass of the i-th subsample, in grams (g);

ρ _i is the density of the i-th density diiodomethane sorting solution, and the unit is grams/cubic centimeter (g/cm ³ ).

Preferably, in step (1), a high-speed mixer is used for stirring at 10,000 rpm for 20 minutes to ensure uniformity of the sample.

Preferably, in step (2), the drilling fluid sample is preferably 50 mL, and the volume of the diiodomethane sorting solution added in step (5) is 100 mL.

Preferably, in step (5), add the diiodomethane sorting solution, use a high-speed mixer to fully stir for 10 minutes, then put it into an ultrasonic cleaner for dispersion for 20 minutes, centrifuge at 2500-4000rpm for 5-10 minutes, and dry in an oven The conditions are that the temperature is 80°C and the time is 12-24h.

Where the present invention is not exhaustive, reference can be made to the prior art.

The beneficial effects of the present invention are:

1) The present invention uses the separation liquid as the medium to carry out the solid phase separation according to the Archimedes buoyancy principle. When sorting, the density of the sorting liquid is required to be between the densities of light and heavy minerals, so that the particles of light minerals are suspended in the upper layer of the sorting liquid, while the heavy minerals sink in the lower layer of the sorting liquid, so as to achieve separation. selected purpose. In addition, since some easily hydrated clay minerals exist in the solid phase of the oil-based drilling fluid, an aqueous solution cannot be used as the separation fluid.

2) In the present invention, since the solid phases in the drilling fluid are separated according to the density of the sorting fluid, the solid phases of different densities are separated, and the materials that do not belong to the low-density solid phase density range are eliminated, which greatly improves the measurement accuracy, and The smaller the density interval of the separation liquid, the higher the separation accuracy.

3) The present invention has the advantages of strong operability and high accuracy of results, and can be used to measure the low-density solid phase content of oil-based drilling fluids to provide reference for the drilling process.

Detailed ways:

In order to make those skilled in the art better understand the technical solutions in this specification, the technical solutions in the embodiments of the present invention are described clearly and completely below, but not limited to this. conventional technology in the field.

Example 1

A method for detecting low-density solid phase content of oil-based drilling fluid, comprising the following steps:

(1) Take the oil-based drilling fluid sample provided on site, and use a high-speed mixer to stir at 10,000 rpm for 20 minutes to ensure that the sample is uniform;

(2) Transfer 50 mL of drilling fluid sample to the sample cup of the drilling fluid oil-water solid content device, and use it in accordance with the national standard GB/T 16783.2-2012 "On-site Testing of Drilling Fluids in Oil and Gas Industry Part 2: Oil-Based Drilling Fluids" Determination of Oil, Water and Solids Contents by Distillation Determination of the volume of oil and water by the described assay procedure;

And using the measured oil and water volume, and the original drilling fluid sample volume, calculate the volume fraction of oil, water and solid phase;

(3) the solid phase obtained after distillation is pulverized by a pulverizer and then dried and preserved;

(4) The preparation density is 1.8g/ ^cm3 , 2.0g/ ^cm3 , 2.2g/ ^cm3 , 2.4g/ ^cm3 , 2.6g/ ^cm3 , 2.8g/ ^cm3 , 3.0g/ ^cm3 , 3.2g /cm ³ Diiodomethane sorting solution for use;

(5) Use the diiodomethane sorting fluid with the density from low to high in turn, and separate the solid phase of the drilling fluid by the method of floating and sinking to form different densities. The specific:

1, the solid phase that step ( ³ ) is obtained is poured into centrifuge tank, adding 100mL density is 1.8g/cm Diiodomethane sorting solution, fully stir 10min, put into ultrasonic cleaner after dispersion 20min, at 3000rpm Centrifuge at the rotating speed for 10 minutes, filter the upper suspension after centrifugation, turn on the switch of the suction pump, and pour the solid-liquid mixture slowly. After drying for 12h, a sample with a density of ρ≤1.8g/ ^cm3 is obtained, and the filtrate is replenished and recycled;

The sorting principle of the present invention is that when the solid phase and the liquid phase have a density difference, when the density is less than the density of the sorting liquid, it floats up, and when the density is greater than the density of the sorting liquid, it sinks;

The low-density solid phase in the oil-based drilling fluid is rock minerals, and the density is generally not lower than 1.8g/cm ³ . Therefore, a separation fluid with a density of 1.8g/cm ³ is used to remove the solid phase with a density lower than 1.8.

II. Pour 100 mL ^of the diiodomethane sorting solution with a density of 2.0 g/cm into the centrifuge tank and mix with the lower sediment after the centrifugation in the previous step, fully stir for 10 min, put it into the ultrasonic cleaner for dispersion for 20 min, Centrifuge at 3000rpm for 10min, filter the upper suspension after centrifugation, and dry it in an oven at 80°C for 12h to obtain a sample of 1.8g/cm ³ <ρ≤2.0g/cm ³ , and the filtrate is replenished and recycled;

III. Repeat the above steps continuously to obtain the density of 2.0g/cm ³ <ρ≤2.2g/cm ³ , 2.2g/cm ³ <ρ≤2.4g/cm ³ , 2.4g/cm ³ <ρ≤2.6g in turn /cm ³ , 2.6g/cm ³ <ρ≤2.8g/cm ³ , 2.8g/cm ³ <ρ≤3.0g/cm ³ , 3.0g/cm ³ <ρ≤3.2g/cm ³ and ρ>3.2g /cm ³ , wherein ρ>3.2g/cm ³ is obtained by filtering, washing and drying the lower sediment after the last centrifugation;

(6) Weigh each sub-sample obtained above, and calculate the volume of each sub-sample;

(7) Since the density range of the low-density solid phase in the drilling fluid is 2.0-3.2g/cm ³ , ρ≤1.8g/cm ³ , 1.8g/cm ³ <ρ≤2.0g/cm ³ and ρ>3.2 The sub-sample volume of g/cm ³ is excluded, that is, the volume of the low-density solid phase does not need to be included in the calculation of the low-density solid phase.

Example 2

A method for detecting low-density solid phase content of oil-based drilling fluid, as shown in Example 1, the difference is that in step (2), the volume fraction of oil in the drilling fluid sample is calculated:

in:

为油占样品总体积的百分数，％；

is the percentage of oil in the total volume of the sample, %;

V _o is the volume of oil in milliliters (mL);

V _s is the volume of the drilling fluid sample, in milliliters (mL);

Calculate the volume of water in the drilling fluid sample:

in:

为水占样品总体积的百分数，％；

is the percentage of water in the total volume of the sample, %;

V _w is the volume of water, in milliliters (mL);

V _s is the volume of the drilling fluid sample, in milliliters (mL);

The solid phase volume fraction is:

in:

为蒸馏固相占样品总体积的百分数，％。

It is the percentage of the total volume of the sample in the distillation solid phase, %.

Example 3

A method for detecting low-density solid phase content of oil-based drilling fluid, as shown in Example 1, the difference is that in step (4), the process of preparing the diiodomethane sorting solution is:

Take a certain mass of chloroform and add it to diiodomethane, transfer it to an airtight container and shake it up. The density of the prepared diiodomethane sorting solution can be calculated from the following formula:

Wherein, M _chloroform is the mass of chloroform, and the unit is g;

M _{diiodomethane} is the mass of diiodomethane, in g;

V _{sorting liquid} is the volume of sorting liquid, the unit is mL;

ρ _{sorting liquid} is the density of sorting liquid, and the unit is g/cm ³ .

Example 4

A method for detecting the low-density solid phase content of oil-based drilling fluid, as shown in Example 3, the difference is that in step (6), the volume of each sample is:

in:

V _i is the i-th subsample volume, in cubic centimeters (cm ³ );

M _i is the mass of the i-th subsample, in grams (g);

ρ _i is the density of the i-th density diiodomethane sorting solution, and the unit is grams/cubic centimeter (g/cm ³ ).

The above are the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1. The method for detecting the low-density solid content of the oil-based drilling fluid is characterized by comprising the following steps of:

(1) taking an oil-based drilling fluid sample and uniformly stirring;

(2) transferring a certain amount of drilling fluid samples to a sample cup of a drilling fluid oil-water solid content device, measuring the volume of oil and water in the drilling fluid by adopting a distillation method, and calculating to obtain the volume fractions of the oil, the water and the solid by using the measured volume of the oil and the water and the volume of an original drilling fluid sample;

(3) crushing the solid phase obtained after distillation by using a crusher, and drying and storing;

(4) preparing a plurality of diiodomethane sorting solutions with different densities for later use, wherein the diiodomethane sorting solutions comprise a first density diiodomethane sorting solution, a second density diiodomethane sorting solution, an Nth density diiodomethane sorting solution, and N is more than or equal to 3;

(5) the method comprises the following steps of sequentially using diiodomethane separation liquid with the density from low to high to form samples with different densities from a drilling fluid solid phase by a floating and settling separation method, specifically:

I. pouring the solid phase obtained in the step (3) into a centrifugal tank, adding a first-density diiodomethane separation solution, fully stirring, dispersing, centrifuging, carrying out suction filtration on the centrifuged upper-layer suspended matter, and drying in an oven to obtain a sample with the density less than the first density;

II. Pouring the second-density diiodomethane separation liquid into a centrifugal tank to be mixed with the lower-layer precipitate after the previous step of centrifugation, fully stirring and dispersing, centrifuging, carrying out suction filtration on the centrifuged upper-layer suspended matter, and drying in an oven to obtain a sample with the density between the first density and the second density;

III, continuously repeating the step II until the N-th density diiodomethane separation liquid is poured into a centrifugal tank to be mixed with the lower-layer precipitate after the previous step of centrifugation, fully stirring and dispersing, centrifuging, carrying out suction filtration on the centrifuged upper-layer suspended matter, drying in an oven to obtain a sample with the density between the N density and the N-1 density, and simultaneously filtering, washing and drying the centrifuged lower-layer precipitate to obtain a sample with the density greater than the N density; thus, obtaining N +1 samples;

(6) weighing the mass of each partial sample, and calculating the volume of each partial sample;

(7) and rejecting the sample separation volume which does not belong to the density range of the low-density solid phase according to the density range of the low-density solid phase in the drilling fluid.

2. The method for detecting the content of the low-density solid phase in the oil-based drilling fluid according to claim 1, wherein in the step (2), the volume fraction of the oil in the drilling fluid sample is calculated as follows:

wherein:

is the percentage of oil to the total volume of the sample,%;

V _o volume of oil in milliliters;

V _s the volume of the drilling fluid sample is milliliter;

calculating the volume of water in the drilling fluid sample:

wherein:

is the percentage of water to the total volume of the sample,%;

V _w is the volume of water in milliliters;

V _s the volume of the drilling fluid sample is milliliter;

the solid phase volume fraction is:

wherein:

as a percentage of the total volume of the sample, the distillation solid phase.

3. The method for detecting the content of the low-density solid phase of the oil-based drilling fluid according to claim 1, wherein in the step (4), the density of a plurality of diiodomethane sorting liquids is in an arithmetic progression from low to high.

4. The method for detecting the content of the low-density solid phase in the oil-based drilling fluid according to claim 3, wherein the density of the low-density solid phase in the drilling fluid is in a range of 2.0 to 3.2g/cm ³ The first density of diiodomethane sorting is preferably 1.8g/cm ³ The Nth density is 3.2g/cm ³ 。

5. The method for detecting the content of the low-density solid phase of the oil-based drilling fluid according to claim 4, wherein in the step (4), the process of preparing the diiodomethane sorting solution comprises the following steps:

adding a certain mass of chloroform into diiodomethane, transferring the mixture into a closed container, and shaking the mixture uniformly, wherein the density of the prepared diiodomethane separation liquid is calculated by the following formula:

wherein M is _Chloroform Is the mass of chloroform, in g;

M _{diiodomethane} Is the mass of diiodomethane in g;

V _{sorting liquid} The volume of the sorting solution is mL;

ρ _{sorting liquid} The density of the sorting solution is given in g/cm ³ 。

6. The method for detecting the content of the low-density solid phase of the oil-based drilling fluid as claimed in claim 5, wherein the density of the diiodomethane sorting fluid is preferably 1.8g/cm ³ 、2.0g/cm ³ 、2.2g/cm ³ 、2.4g/cm ³ 、2.6g/cm ³ 、2.8g/cm ³ 、3.0g/cm ³ And 3.2g/cm ³ The obtained sample density is rho is less than or equal to 1.8g/cm ³ 、1.8g/cm ³ ＜ρ≤2.0g/cm ³ 、2.0g/cm ³ ＜ρ≤2.2g/cm ³ 、2.2g/cm ³ ＜ρ≤2.4g/cm ³ 、2.4g/cm ³ ＜ρ≤2.6g/cm ³ 、2.6g/cm ³ ＜ρ≤2.8g/cm ³ 、2.8g/cm ³ ＜ρ≤3.0g/cm ³ 、3.0g/cm ³ ＜ρ≤3.2g/cm ³ And p > 3.2g/cm ³ In the step (7), rho is less than or equal to 1.8g/cm ³ 、1.8g/cm ³ ＜ρ≤2.0g/cm ³ 、ρ＞3.2g/cm ³ And (4) removing the sample volume.

7. The method for detecting the content of the low-density solid phase of the oil-based drilling fluid according to claim 1, wherein in the step (6), the volume of each partial sample is as follows:

wherein:

V _i is as followsi sample volumes are divided, and the unit is cubic centimeter;

M _i the ith sample weight is gram;

ρ _i is the density of the ith density diiodomethane sort solution in grams per cubic centimeter.

8. The method for detecting the content of the low-density solid phase of the oil-based drilling fluid as claimed in claim 1, wherein in the step (1), the sample is uniformly stirred by using a high-speed stirrer at 10000rpm for 20 min.

9. The method for detecting the content of the low-density solid phase of the oil-based drilling fluid according to claim 1, wherein in the step (2), the drilling fluid sample is preferably 50mL, and the volume of the diiodomethane sorting fluid added in the step (5) is 100 mL.

10. The method for detecting the content of the low-density solid phase of the oil-based drilling fluid as claimed in claim 1, wherein in the step (5), the diiodomethane separation liquid is added, fully stirred for 10min by a high-speed stirrer, and then placed into an ultrasonic cleaner for dispersion for 20min, and then centrifuged for 5-10 min at the rotation speed of 2500-.