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Method for transforming coal bed gas horizontal well system

A technology for horizontal wells and coalbed methane, applied in the direction of earthwork drilling, wellbore/well components, and production fluids, etc. It can solve the problems of lost circulation, collapse and sticking, low-efficiency development, unfavorable high production, etc., and improve drainage and production efficiency , Speed ​​up the construction progress and promote the effect of development

Pending Publication Date: 2021-05-28
河北佐和佑石油技术发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, structural coal and low-rank coal, which account for 80%, are still in an inefficient development state, that is, the input-output ratio is very poor
[0004] The main problems are: first, the production efficiency of vertical wells and directional wells is low
Second, the conventional horizontal well technology has poor wellbore stability in low-rank coal and tectonic coal seams, is prone to collapse, and is prone to complex accidents such as lost circulation and collapse and stuck pipe
Fifth, the trajectory of the coal seam has a great influence on the drainage; with the change of the inclination angle of the coal seam, grooves are easy to form in some well sections, and water plugs are formed when the drainage is put into production
When there is structural coal at the bottom of the coal seam and is drilled, coal ash will accumulate in the groove, causing "ash plugging" during mining, which is not conducive to high production
Sixth, low-rank coal seams have characteristics such as low permeability and coal fragmentation, resulting in low or no gas production in CBM wells
However, in the solution provided by this patent, the horizontal well is drilled in the coal seam, which still does not solve the problem of the borehole wall collapse of the low-rank coal, and with the prolongation of the mining time, the seepage channel is gradually blocked, resulting in low or no gas production in the later stage. The problem of gas production, the actual extraction efficiency is not high

Method used

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  • Method for transforming coal bed gas horizontal well system
  • Method for transforming coal bed gas horizontal well system
  • Method for transforming coal bed gas horizontal well system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0116] Such as figure 1As shown, the first horizontal well (that is, the vertical section of the first horizontal well track 1) uses a D311.2mm roller cone bit, and the drilling tool combination: Φ311.15mmPDC+Φ177.8mmX / O+Φ177mmDC+Φ165mmDC+Φ165mmX / O+ Φ127mmDP, Bantu mud drilling fluid drilled through the bedrock weathered zone for 20m, completed drilling at a depth of 60-80m, and lowered the D24.5mm surface casing with cement injection for full sealing. The main function of the first opening is to seal the loose layer and gravel layer on the surface .

[0117] D215.9mm drill bit is used for the second opening of the horizontal well (that is, the bending section of the first horizontal well trajectory 1), and the drill tool assembly: Φ215.9mmPDC+Φ172mm*1.5°Motor+Φ172mmFV+Φ172mmUBHO+Φ172mmNMDC+Φ127mmDP+Φ127mmHWDP; drilling purpose After the coal seam, drill 10-20m with a well inclination angle of 90°-98° and keep it 0.2-2.0m below the target coal seam, then pull out the drill, r...

Embodiment 2

[0124] As soon as the horizontal well was opened (that is, the vertical section of the first horizontal well track 1), the D311.2mm roller cone bit was used to drill through the bedrock weathered zone for 20m, and the drilling was completed at a depth of 60m, and the D244.5mm surface casing was run and sealed. Surface loose layer, gravel layer. The entry depth is 58m, and the cement is fully sealed.

[0125] The second opening (that is, the bending section and the horizontal section of the first horizontal well trajectory 1) uses D215.9mm drill bit, drill tool assembly: Φ215.9mm PDC+Φ172mm*1.5°Motor+X / O+Φ172mmFV+Φ172mmUBHO+Φ172mmNMDC+NMDC +GAP+NMDC+Φ127mmHWDP+Φ127mmDP; the near-bit instrument or rotary steerable instrument can be used to speed up the ROP, and after drilling through the target coal seam, drill with a well inclination angle of 90°~98° and keep it 0.2~2.0m below the target coal seam 300-2000m After the completion of the first horizontal well trajectory 1, the dr...

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Abstract

The invention discloses a method for transforming a coal bed gas horizontal well system. The method comprises the following steps that a low-rank coal bed or a construction coal bed is selected for transformation; a first horizontal well track drills through a lower bottom plate of a target coal bed, and then drilling is carried out in the horizontal direction according to the coal bed track; cement is adopted for well cementation in the first horizontal well track; windowing sidetracking is carried out on the first horizontal well track at the upper boundary portion of the target coal bed and the position with the well deviation angle being 45-75 degrees to form a second horizontal well track, and then drilling is carried out in the horizontal direction; production casing pipes are put from the horizontal section of the first horizontal well track to the well bottom and from the windowing sidetracking point of the second horizontal well track to the well bottom respectively to form a first horizontal well and a second horizontal well; directional perforation is carried out on the second horizontal well downwards, and large-scale staged fracturing or dragging fracturing is carried out; directional perforation is carried out on the first horizontal well upwards, and hydraulic jetting or small fracturing seam forming is carried out; and an oil pipe is put to the lower boundary of coal bed gas for water drainage and pressure reduction gas recovery. The development efficiency of the coal bed gas on construction coal and low-rank coal is improved.

Description

technical field [0001] The invention relates to the technical field of exploitation of underground fluid resources, in particular to a method for reforming a coalbed methane horizontal well system. Background technique [0002] Coalbed methane is usually exploited by vertical wells, directional wells and horizontal wells, and the common horizontal well technology is divided into single main branch horizontal well, two main branch multi branch horizontal well, single main branch multi branch horizontal well and multi-stage pressure well. Fractured U-shaped horizontal wells and secondary multi-stage fracturing horizontal wells, the common goal of various mining methods is to improve the efficiency of coalbed methane mining and increase the input-output ratio. [0003] Due to the diversity of coal seam geological conditions in different regions of my country, as well as the different content of high, medium and low coal ranks in each block, the mining effect is very different. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/00E21B43/30E21B43/26E21B33/134
CPCE21B33/134E21B43/006E21B43/26E21B43/305
Inventor 陈天昊
Owner 河北佐和佑石油技术发展有限公司
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