RU1572097C - Method for driving horizontal wells - Google Patents

Abstract

FIELD: drilling of deep exploratory and flow wells. SUBSTANCE: method involves drilling a vertical shaft 1 which intersects the flow bed 2, installing an artificial geophysical bench mark 3 (e.g. a magnetic one) above the cutting-in point 4 of inclined shaft section to mark the depth of the well. Then locations of bed 2 and cutting-in point 4 of inclined shaft section are determined with relation to bench mark 3, drilling said inclined section of shaft with the aid of deflecting device. The trajectory of the inclined section is corrected for depth with relation to bench mark 3. The location of bench mark 3 is recorded by magnetic transmitter of inclinometer. EFFECT: higher drilling accuracy of horizontal wells and of hitting a producing bed. 2 cl, 2 dwg

Description

The invention relates to drilling deep exploratory and production wells and is intended for the wiring horizontal branched horizontal and multilateral wells, where one of the trudnoispolnimyh technological methods is the current trunk hit into predetermined producing formation at an angle close to ⁹⁰ °, particularly when the the thickness of this layer is small, and the means of controlling the trajectory have low accuracy indicators.

 The purpose of the invention is to increase the accuracy of wiring and getting into the reservoir of low power.

 In FIG. 1 shows a wiring diagram of a horizontal wellbore; in FIG. 2 is a diagram of the geophysical linking of an artificial benchmark to a reservoir.

 The method of posting horizontal wells is implemented by the following sequence of operations.

 Carry out the drilling of a vertical wellbore crossing the reservoir. Using geophysical studies, the boundaries of occurrence, the thickness of the reservoir, the geological and lithological composition of the reservoir, its homogeneity and other physical properties necessary for further successful operation (porosity, clay, oil saturation, etc.) are determined.

 In accordance with the required intensity of the zenith angle set of the deviated wellbore, the bottom of the drill string is selected including a deflector of a certain type and size, and the position of the insertion point of the inclined stem relative to a given horizon of the reservoir is calculated. 15-20 m above the calculated insertion point of the inclined section of the barrel (determined by the distance from the tool bit to the location of the inclinometric sensors), an artificial geophysical benchmark is installed on the side wall of the well, which serves as a depth benchmark. As a benchmark, a spring steel strip can be installed, shunting the electrical resistivity of the layers, or a radioactive bullet that creates an anomaly of gamma activity at the installation point. Magnetic geophysical benchmark can be installed using zero perforators type PVK-70, PVT-73, one of the trunks of which is charged with a bullet of magnetized diffusion hardening hard alloy with magnetic anisotropy type UN15DK25BA. The magnetic reference can be registered with currently existing inclinometric equipment.

 Geophysical method determines the position of the reservoir relative to the reference depth of the well. By calculation, determine the location of the insertion of the inclined section of the wellbore relative to the depth reference, for example magnetic, and fill the sump of the well to the point of insertion of the inclined hole with cement. After the cement hardening process is completed, the drill tool with an inclinometer is lowered on the drill pipe string, the magnetic sensors of which record a magnetic reference point, install the tool at the point of insertion of the inclined shaft and drill it using a deflection device to enter the reservoir. In the process of drilling (or when it stops), the inclined section of the trunk is posted, adjusting its path in depth relative to the benchmark, which is necessary for falling into a given horizon.

 With each change of bit, as well as if it is necessary to exclude random errors of inclinometric sensors, the registration of the trajectory of an intensive set of curvature of the wellbore with fixing the position of the magnetic reference on the recorded diagrams is performed several times.

 Drilling a vertical wellbore (Fig. 1) is carried out using one of the known methods of drilling to an estimated depth at which the wellbore 1 completely intersects the productive formation 2. After lifting the drilling tool, the well is examined by field-geophysical means, the formation 2 is repelled and its geometrical parameters are checked. Based on this information, the depth L of the geometric middle of the reservoir 2 is fixed and the radius of the circle specified in the design of curvature is calculated. An artificial magnetic benchmark 3 is installed 18 m above this point (distance from the bit to the inclinometric sensors) using a bullet punch. The sump of the well is filled with cement 5 to the location 4 of the insert of the inclined shaft 5. Geophysical method determines the position of benchmark 3 from mark 6 on curve 7 (Fig. .2) relative to the specified horizon for drilling the reservoir 2, corresponding to curve 8 in figure 2, and calculate the location 4 of the insertion of the inclined section of the wellbore relative to the magnetic reference 3. After the shutter cement cement 5 run the drill string with a deflecting device (for example, a curved sub) and a flux-gate inclinometric telemetry system register magnetic reference 3 with inclinometer sensors, set the bit at the tie-in location 4 and drill the inclined section of the shaft, adjusting its trajectory in depth relative to the reference 4.

l; cos θ_{i ,} где Н - глубина расположения репера;
l_i - длина интервалов после местоположения репера между ближайшими точками наблюдения инклинометра;
θ_i - зенитный угол интервала l_i;.Since the location of the benchmark in depth is known, mark 6, in which a benchmark is registered in the magnetic azimuth diagram of the well, gives the exact value of the depth of the well. In this case, all accumulated errors in determining the vertical projection of the wellbore to the depth of the reference location are zeroed and a further countdown of the vertical projection h of the well is carried out from the ratio
h = H +

l; cos θ _{i ,} where H is the depth of the reference;
l _i - the length of the intervals after the location of the reference between the nearest observation points of the inclinometer;
θ _i is the zenith angle of the interval l _i ;.

Since the artificial geophysical benchmark is installed near the calculated insertion point of the inclined section of the wellbore, then H >> l _i cos θ _i , which eliminates the main error of inclinometric measurements of the vertical projection h of the barrel, which accumulates with increasing depth of the well.

, где l₂ - глубина местоположения искусственного репера;
l₁ - расстояние от репера до середины продуктивного пласта.Improving Accuracy t _Inc. directional measurements at solving this problem is defined by the expression
t _Inc. =

where l ₂ is the depth of the location of the artificial frame;
l ₁ - the distance from the benchmark to the middle of the reservoir.

For example, for horizontal well 196 of the Novo-Uzybash area, l ₂ and l ₁ are 2100 and 120 m, which corresponds to an increase in the accuracy of inclinometric measurements by 17 times.

 This method allows you to adjust the well’s trajectory not by summing the vertical projections of the entire wellbore traveled, but by installing an artificial magnetic reference above the calculated insertion point of the inclined section, determining the position of the reservoir relative to the depth reference and registering it with magnetic inclinometer sensors, in connection with which it is possible to correct the trajectory only by summing the vertical projections of the trunk below the re position EPA.

 The ability to perform multiple inclinometric measurements of the well trajectory during drilling of the geophysical well with all the measurements tied to the well depth gauge recorded by the inclinometer eliminates random errors in inclinometric measurements, which increases the accuracy of horizontal wells and penetration into the reservoir.

Claims (2)

 1. METHOD FOR HORIZONTAL WELLS WIRING, including drilling a vertical well that crosses the producing formation, determining the position of the producing formation relative to the depth gauge, determining the location of the insert of the inclined section of the well relative to the well depth gauge, and drilling the inclined well using a deflecting device before entering the reservoir, different the fact that, in order to improve the accuracy of wiring and getting into the reservoir low power, set higher than the insertion point of the inclined section of the wellbore with an artificial geophysical benchmark and record its location, and when posting the inclined section, its trajectory is adjusted in depth relative to the reference point.  2. The method according to claim 1, characterized in that a magnetic reference is installed in the well, and registration of its location is carried out by magnetic sensors of the inclinometer.

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