阅读说明：本技术 一种超深水平井井眼轨道设计方法 (Ultra-deep horizontal well borehole orbit design method ) 是由 黄贵生 李林 罗朝东 沈建文 睢圣 曲其勇 黄胜强 于 2020-04-29 设计创作，主要内容包括：本发明公开了一种超深水平井井眼轨道设计方法,所述设计方法根据获得的地层岩石强度和地层可钻性数据,将预定造斜段处的地层按照可钻性分层,以可钻性级值低的地层的造斜率大于可钻性级值高的地层的造斜率进行逐层增斜。本发明针对超深水平井的特殊性,通过将预定造斜段处的地层按照可钻性分层,并以可钻性级值低的地层的造斜率大于可钻性级值高的地层的造斜率进行逐层增斜,从而在超深水平井的预定造斜段处形成分层的“多增-多调”式井眼轨道优化设计,钻具根据设计的井眼轨道钻进时,能够有效减少在难钻地层的滑动钻进比例,以快速钻穿高研磨性地层、减少在破碎地层滑动进尺,安全性、高效性和精度好。(The invention discloses a design method of a borehole track of an ultra-deep horizontal well, which comprises the steps of layering stratums at a preset deflecting section according to the drillability according to the obtained stratum rock strength and stratum drillability data, and increasing the deflection layer by using the deflecting rate of the stratum with a low drillability level value larger than that of the stratum with a high drillability level value. Aiming at the particularity of the ultra-deep horizontal well, the stratum at the preset deflecting section is layered according to the drillability, and the gradient of the stratum with the low drillability level value is larger than the gradient of the stratum with the high drillability level value to increase the deflection layer by layer, so that the layered multi-increment-multi-tone well track is formed at the preset deflecting section of the ultra-deep horizontal well, the drilling tool can effectively reduce the sliding drilling proportion of the stratum difficult to drill according to the designed well track during drilling, the highly abrasive stratum is drilled quickly, the sliding footage on the broken stratum is reduced, and the safety, the efficiency and the precision are good.)

1. The design method is characterized in that the stratum at a preset deflecting section is layered according to the drillability according to the obtained stratum rock strength and stratum drillability data, and the layer-by-layer deflection is increased by using the deflecting rate of the stratum with a low drillability level value larger than that of the stratum with a high drillability level value.

2. The method for designing the wellbore trajectory of the ultra-deep horizontal well according to claim 1, wherein the build-up rate of the stratum with the low drillability level value is 15-20 °/100 m.

3. The method for designing the wellbore trajectory of the ultra-deep horizontal well according to claim 1, wherein the build-up rate of the stratum with the high drillability level value is 5-10 °/100 m.

4. The ultra-deep horizontal well bore trajectory design method of claim 1, wherein the deflecting section takes a natural deflection increasing end point of composite drilling as a deflection increasing starting point.

5. The ultra-deep horizontal well track design method according to claim 1 or 4, wherein the build rate of the first slope increasing section at the build section is 10-15 °/100 m.

6. The ultra-deep horizontal well track design method according to claim 1 or 4, wherein the build rate of the last slope increasing section at the build section is 10-15 °/100 m.

7. The method for designing the borehole trajectory of the ultra-deep horizontal well according to claim 1, wherein the stratum with the high drillability level value is a stratum with the hardness of more than or equal to 1000MPa and the drillability level value of more than or equal to 8.

Technical Field

The invention relates to a borehole track design technology for oil and gas reservoir development, in particular to a borehole track design method for an ultra-deep horizontal well.

Background

Along with the continuous deepening of oil exploration and development, high-quality oil and gas reservoirs with low exploitation difficulty are less and less, most of oil and gas reservoirs without exploitation have the characteristics of deep reservoir burial depth, thin sand body monolayer thickness, obvious lithology and physical property transverse change and the like, the exploitation technology difficulty is high, and the economic benefit is poor.

The horizontal well is used as a main method for improving the recovery efficiency of the oil-gas reservoir and is widely applied to the development of the oil-gas reservoir. The key factors influencing the drilling efficiency of the horizontal well are the design of the well track, namely whether the well track of the horizontal well is reasonable or not, and the drilling efficiency of the horizontal well and even the success or failure of drilling are directly related.

At present, the borehole track design of the horizontal well mainly adopts a three-section system technology of 'straight-increasing-stabilizing' and a five-section system technology of 'straight-increasing-stabilizing'. The horizontal well track design technology adopts a single build-up rate, namely the well track design is carried out by the single build-up rate, and the technical problem is not obvious when the horizontal well track design technology is applied to a shallow well or a deep well. However, when the horizontal well track designed by adopting a single build-up rate is applied to an ultra-deep well, the drilling tool cannot reduce the sliding drilling proportion in the difficult-to-drill stratum due to the fact that the ultra-deep well has multiple stratum-crossing sequences, large difference of drillable level values of different stratums, deep depth of the build-up point and the like, so that the drilling tool forms frequent sliding drilling in a long well section of the difficult-to-drill stratum, and the drilling safety, the mechanical drilling speed and the precision of the well track are directly influenced.

Disclosure of Invention

The technical purpose of the invention is as follows: aiming at the defects of the prior art, the design method of the ultra-deep horizontal well borehole track is provided, which can effectively reduce the sliding drilling proportion of the drilling tool in the difficult-to-drill stratum.

The technical purpose of the invention is realized by the following technical scheme: according to the design method, the stratum at a preset deflecting section is layered according to the drillability according to the obtained stratum rock strength and stratum drillability data, and the layer-by-layer deflection is increased by using the deflecting rate of the stratum with a low drillability level value larger than that of the stratum with a high drillability level value.

Preferably, the build-up rate of the stratum with the low drillability level value is 15-20 DEG/100 m.

Preferably, the build-up rate of the stratum with the high drillability level value is 5-10 DEG/100 m.

As one preferable scheme, the natural inclination-increasing end point of the composite drilling is taken as an inclination-increasing starting point at the deflecting section.

Preferably, the slope of the first slope increasing section at the slope building section is 10-15 °/100 m.

Preferably, the last inclination increasing section at the inclined section has an inclination of 10-15 DEG/100 m.

As one preferable scheme, the stratum with high drillability level value is the stratum with hardness of more than or equal to 1000MPa and drillability level value of more than or equal to 8.

The beneficial technical effects of the invention are as follows:

1. aiming at the particularity of the ultra-deep horizontal well, the stratum at the preset deflecting section is layered according to drillability, and the gradient of the stratum with the low drillability level value is larger than that of the stratum with the high drillability level value to increase the deflection layer by layer, so that the layered multi-increment-multi-tone well track optimization design is formed at the preset deflecting section of the ultra-deep horizontal well, and when a drilling tool drills according to the designed well track, the drilling tool can effectively reduce the sliding drilling proportion of the stratum which is difficult to drill, so that the highly abrasive stratum can be drilled quickly, the sliding footage of the broken stratum is reduced, and the safety, the efficiency and the precision are good;

2. the method reasonably selects the build-up rate of the stratum with low drillable level value and the stratum with high drillable level value, effectively balances the change of the drilling speed and the build-up rate, enables the coordinates of a wellhead and the coordinates of a target point to be reasonably and reliably communicated, and further improves the safety, the efficiency and the precision;

3. according to the method, the construction rate of the first slope increasing section at the construction section is reasonably selected, so that the problem of insufficient construction rate at the initial stage is effectively avoided, and the drilling speed and the construction rate change are balanced;

4. the method is favorable for adjusting the vertical depth of the target layer by reasonably selecting the build-up rate of the last build-up section at the build-up section so as to ensure that the coordinates of the wellhead and the coordinates of the target point can be reasonably and reliably communicated and improve the drilling precision;

5. the deflecting section of the invention takes the natural deflecting end point of the composite drilling as the deflecting starting point, fully utilizes the natural deflecting trend of the composite drilling, lifts the deflecting point, reduces the deflecting rate and effectively reduces the sliding drilling proportion of the drilling tool in the difficult-to-drill stratum.

Drawings

FIG. 1 is a schematic diagram of a wellbore trajectory designed for a three-open ultra-deep horizontal well in the West-Sichuan sea according to the present invention.

Detailed Description

The invention relates to a borehole track design technology for oil and gas reservoir development, in particular to a borehole track design method for an ultra-deep horizontal well.

The invention relates to a method for designing a borehole track of an ultra-deep horizontal well, wherein the borehole track design at a vertical well section and a horizontal well section is the same as the conventional design technology, and the detailed description is omitted. The present invention contributes to the prior art by the design of the wellbore trajectory at the whipstock.

The method for designing the well track comprises the following technical measures:

-obtaining natural deviation increasing trend data of the composite drilling and rock strength and drillability data of the formation in which the predetermined deviation segment is located;

-determining a starting point of the deflection at a predetermined deflecting section according to the obtained data of the natural deflection increasing trend of the composite drilling, the starting point of the deflection increasing being a natural deflection increasing end point of the composite drilling;

-stratifying the formation at the predetermined whipstock section successively according to the drillability based on the obtained formation rock strength and formation drillability data;

specifically, the stratum with the hardness of more than or equal to 1000MPa and the drillability level value of more than or equal to 8 is divided into the stratum with the high drillability level value, and the stratum with the hardness of less than 1000MPa and the drillability level value of less than 8 is divided into the stratum with the low drillability level value; the strata layered successively according to drillability are arranged from top to bottom;

-performing a layer-by-layer build-up with the build-up rate of the formation with a low value of drillability being greater than the build-up rate of the formation with a high value of drillability, based on the determined build-up start and the stratification by formation drillability;

specifically, the build-up rate range of the first inclination-increasing section is 10-15 degrees/100 m, and the well inclination change range is 0-20 degrees;

the slope making rate of the final slope increasing section is 10-15 degrees/100 m, and the well deviation change range is 70 degrees to the designed well deviation;

in each layer between the first inclination-increasing section and the last inclination-increasing section, the build-up rate range of the stratum with low drillability level value is 15-20 degrees/100 m, and the build-up rate range of the stratum with high drillability level value is 5-10 degrees/100 m.

The formation gradient in each of the above ranges is appropriately selected according to the specific formation conditions, for example, the formation gradient of the first slope increasing section is 10 °/100m, 12 °/100m, 13 °/100m, or 15 °/100 m; the slope making rate of the final slope increasing section is 10 °/100m, 12 °/100m, 13 °/100m or 15 °/100m, etc.; in each layer between the first inclination-increasing section and the last inclination-increasing section, the build-up rate of the stratum with low drillability level value is 15 degrees/100 m, 16 degrees/100 m, 18 degrees/100 m or 20 degrees/100 m, etc.; in each layer between the first inclined increasing section and the last inclined increasing section, the build-up rate of the stratum with high drillability level value is 5 degrees/100 m, 7 degrees/100 m, 9 degrees/100 m or 10 degrees/100 m, and the like, and the build-up rate of the stratum with high drillability level value is always smaller than that of the stratum with low drillability level value.

According to the technical measures, the invention comprises the technical contents of stratum rock strength and drillability profile analysis, well depth optimization of a deflecting point, size optimization of a deflecting rate, layering increase-modulation and the like.

The main function of the stratum rock strength and drillability profile analysis is to provide stratum physical characteristics influencing the mechanical drilling rate and provide basis for the depth of a deflecting point and the design deflecting rate of stratums of different layers.

The optimal main function of the well depth of the deflecting point is to select reasonable deflecting point depth according to the coordinates of the well head and the coordinates of the target point.

The preferred main function of the formation rate is to select different formation rates depending on the formation rock strength and drillability.

The layered multi-increment-multi-modulation function is used for avoiding various technical defects that the tool face at the initial stage of orientation is unstable, the actual drilling build slope cannot meet the design requirement, the single build slope design causes frequent sliding drilling in a difficult-to-drill stratum, the mechanical drilling speed is low, the reservoir prediction depth error influences the track vector target entering and the like in the conventional borehole track profile design technologies such as 'straight-increment-stable', 'straight-increment-stable-increment-steady', and the like.

Referring to fig. 1, the invention takes the three-open extra-deep horizontal well of the western-style sea as an object, and carries out the simulation design of the borehole orbit, and the engineering geological characteristic parameters of the three-open extra-deep horizontal well of the western-style sea are shown in table 1.

TABLE 1 engineering geological characteristic parameters of three-open ultra-deep horizontal well in Sichuan-West sea facies

The design deflecting point of the three-division ultra-deep well in the sea of Sichuan and West is located in the group of two to small ponds, the hardness is more than 1000MPa, the drillability level value is more than 8, the mechanical drilling speed of the front straight well drilling is only 1.34m/h, the average single-trip drilling depth is only 91m, and the mechanical drilling speed of the directional deflecting drilling of the high-abrasiveness stratum is lower than that of the front straight well composite drilling. The stratum at the top of the reservoir mine mouth slope group is broken, 6 vertical wells are stuck for 12 times in the early stage, and the problem of stability of the well wall is prominent.

Aiming at the difficult problems of low drilling speed of a directional drilling machine for high-abrasive stratum and large safety risk of sliding drilling of the broken stratum, a layered 'multi-increment-multi-modulation' track optimization design scheme is formed, the natural inclination increasing trend of composite drilling is fully utilized, the high-abrasive stratum is quickly drilled through, the sliding footage of the broken stratum is reduced, and the safety is improved.

The layered 'increasing-modulating' track optimization design scheme has the following characteristics:

lifting a build-up slope point, reducing the build-up slope, and rapidly drilling through the high-abrasiveness stratum of the small pond group by utilizing the composite natural slope increasing trend;

by utilizing the characteristic that the drilling performance of the saddle pond group is relatively better, the stable inclined section of the original design is optimized into the inclined increasing section, and the length of the well section of the easily formed cuttings bed is shortened;

the slope of the four segments of the mine is reduced, the sliding footage of the broken stratum is reduced, the safety is improved, and the adjustment of the vertical depth of the target stratum is facilitated.

Through sufficient simulation evaluation and analysis, the well track designed by the layered 'increasing-adjusting-increasing' track optimization design scheme is obviously superior to the well track designed by the single build-up rate track design scheme in the aspects of drilling safety, drilling rate, precision control of the well track and the like of a drilling tool in the III-made ultra-deep horizontal well in the West-Sichuan sea.

The above detailed description is merely illustrative of the present invention and is not to be construed as limiting thereof. Although the present invention has been described in detail with reference to the specific embodiments thereof, it will be understood by those skilled in the art that: the above-mentioned specific technical solutions can still be modified, or some technical features thereof can be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the present invention in its essence.