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Method for improving recovery efficiency through huff and puffoil recoveryof tight oil fractured horizontal well

A technology for horizontal wells and tight oil, applied in the field of oil production from wells, can solve problems such as low recovery rate, and achieve the effects of low investment cost, obvious production stimulation effect and good economic benefit.

Active Publication Date: 2016-08-24
PETROCHINA CO LTD
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

[0008] In order to overcome the problem of low recovery in the existing natural energy depletion development mode in the development of fracturing horizontal wells in tight oil reservoirs, the present invention provides a method for improving oil recovery by huff and puff of fracturing horizontal wells in tight oil reservoirs. The invention improves the imbibition flooding effect of fractured tight oil reservoirs, improves the cross-seepage ability between fractures and matrix in low permeability reservoirs, increases the recovery degree of crude oil, and develops tight oil by using horizontal wells after volume fracturing It fully increases the oil-water contact area in the artificial fractures and natural fractures of the reservoir, and further improves the overall imbibition stimulation effect of the reservoir.

Method used

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  • Method for improving recovery efficiency through huff and puffoil recoveryof tight oil fractured horizontal well
  • Method for improving recovery efficiency through huff and puffoil recoveryof tight oil fractured horizontal well
  • Method for improving recovery efficiency through huff and puffoil recoveryof tight oil fractured horizontal well

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Embodiment 1

[0039] In order to overcome the problem of low recovery rate of the natural energy depletion development mode in the existing tight oil reservoir fracturing horizontal well development, the present invention provides such figure 1 Shown is a method for improving oil recovery by huff and puff recovery of tight oil fracturing horizontal wells. The invention improves the effect of imbibition flooding in fractured tight oil reservoirs, improves the interpenetration capacity between fractures and matrix in low permeability reservoirs, and increases the The degree of crude oil recovery, the use of horizontal wells after volume fracturing to develop tight oil reservoirs, fully increases the oil-water contact area in artificial fractures and natural fractures in the reservoir, and further improves the overall imbibition of the reservoir The effect of increasing production.

[0040] A method for improving oil recovery by huff and puff recovery of tight oil fracturing horizontal wells, ...

Embodiment 2

[0064] Based on the above embodiments, in this embodiment, the oil reservoir is a single-layer oil reservoir with a thickness of 2-100m; the average permeability of the reservoir matrix is ​​generally less than 0.3mD, the average porosity is 9%, and the average fracture density 0.29 bars / m; the reservoir type is an unsaturated, low-pressure reservoir with no bottom water / gas cap.

[0065] The oil well in the oil reservoir is a horizontal well with a horizontal section of 850m and a well row spacing of 600m; when the oil well is completed, the oil well that undergoes staged volume fracturing after casing cementing is used, and the average fracturing Construction displacement>6m 3 / min, the average interval between fracturing stages is 80-100m.

[0066] The pressure at the end of the oil recovery in step 3) is 10 MPa, and the pressure maintenance level is 59%.

[0067] The step 1) is based on numerical simulation research and mineral test analysis, in the water injection stage...

Embodiment 3

[0074]This example mainly focuses on tight oil reservoirs in the Xin'anbian area of ​​the Ordos Basin. This area is one of the tight oil test areas of Changqing Oilfield. The tight oil reservoir is Chang 7 layer, the buried depth of the reservoir is 2190-2570m, and the physical properties of the reservoir are poor (the average porosity obtained by core analysis is 8.9%, and the average permeability is 0.12mD ), the original formation pressure is low (average original formation pressure 15.8MPa, average pressure coefficient 0.81), conventional fracturing vertical wells have low production, and cannot be effectively developed. The head of the district 7 2 The average oil layer thickness of the reservoir is 10m, the porosity of the core analysis is 7%-9%, the average is 8.9%, the permeability is 0.1-0.2mD, the average is 0.12mD, the natural fractures in the reservoir are developed, the average fracture density is 0.29 / m, and the viscosity of the crude oil in the formation is 1.2...

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Abstract

The invention provides a method for improving recovery efficiency through huff and puffoil recovery of a tight oil fractured horizontal well. When reservoir pressure is reduced to a certain optimized pressure, the horizontal well is subjected to sand washing out and well flushing, water is injected into the reservoir at the specified daily water-injection rate, water injection is stopped when pressure at the end of injection life is maintained to be 100%, and then the accumulated water-injection rate is equal to accumulated fluid withdrawal rate in the previous production stage of the well; after water injection is ended, the horizontal well is closed and enters a closing-in stage to depend on imbibition replacement and other effects, so that crude reservoir oil enters a high-permeability channel; and during oil extraction, when formation pressure in the control area of the horizontal well is reduced to rated pressure, the well is closed, and second round of huff and puff oil recovery is performed. According to the method for improving recovery efficiency through the huff and puffoil recovery of the tight oil fractured horizontal well disclosed by the invention, crude oil in dense reservoir rock matrix pores developed in natural fracture is further extracted, the single well yield of an oil well is improved by comprehensively utilizing formation energy rising, injected water and crude reservoir oil imbibition replacement and other principles, and a new approach is developed for increasing the crude oil recovery rate of the dense oil reservoir.

Description

technical field [0001] The invention belongs to the field of oil recovery from wells, and in particular relates to a method for improving oil recovery by huff and puff of horizontal wells with tight oil fracturing. Background technique [0002] Tight oil is the abbreviation of tight reservoir oil, and its main storage spaces are unconventional reservoirs such as tight sandstone, marl, dolomite, and shale. At present, tight oil has been commercially developed in North America, which has brought major changes to the world's oil and gas exploration and development, and is gradually affecting the pattern of world energy supply and demand. Tight oil in my country is mainly in continental facies, with great resource potential and wide distribution, mainly distributed in Songliao, Qaidam, Ordos and Sichuan Basins. Currently, as the number of newly discovered conventional oil fields decreases and the recoverable reserves of oil and gas resources gradually decrease, tight oil will b...

Claims

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Application Information

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IPC IPC(8): E21B43/20E21B43/26
CPCE21B43/20E21B47/06E21B43/26
Inventor 李忠兴赵继勇屈雪峰雷启鸿何右安高武彬刘万涛王选茹陈文龙赵国玺
Owner PETROCHINA CO LTD
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