Temporary blocking turnaround fracturing method based on surface modified polyvinyl alcohol fibers

A polyvinyl alcohol fiber, surface modification technology, applied in chemical instruments and methods, earthwork drilling, drilling composition, etc. problem, to achieve the effect of low cost, simple and easy process and good effect

Active Publication Date: 2015-06-24
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to overcome the low oil and gas production and low recovery rate of the old fractures in the early fracturing, while the conventional diversion fracturing technology has low degree of reservoir transformation, short effective period of measures, and large damage to the reservoir due to particle type temporary plugging agent. Incomplete and other issues

Method used

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  • Temporary blocking turnaround fracturing method based on surface modified polyvinyl alcohol fibers
  • Temporary blocking turnaround fracturing method based on surface modified polyvinyl alcohol fibers

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Effect test

Embodiment 1

[0030] In order to overcome the low oil and gas production and low recovery rate of the old fractures in the early fracturing, the conventional diversion fracturing technology has problems such as low degree of reservoir stimulation, short effective period of measures, large damage to the reservoir by granular temporary plugging agent, and incomplete degradation, etc. , this embodiment provides a figure 1 and figure 2 The shown temporary plugging diversion fracturing method based on surface-modified polyvinyl alcohol fibers includes the following steps:

[0031] 1) Carry out surface modification to water-soluble polyvinyl alcohol fiber, obtain the modified polyvinyl alcohol fiber;

[0032] 2) Preparation of fracturing working fluid; prepare guar gum cross-linking fluid with a mass fraction of 0.3% as preflush, proppant accounts for 15% to 30% of the volume fraction of guar gum cross-linking fluid, and the modified The mass fraction of polyvinyl alcohol fibers in the proppa...

Embodiment 2

[0043] On the basis of Example 1, the chromic acid solution can be used to modify the surface of the water-soluble polyvinyl alcohol fiber in the step 1), and the formula of the chromic acid solution is K 2 Cr 2 o 7 、H 2 O and concentrated H 2 SO 4 The substance mass ratio is 5:8:100, and the water-soluble polyvinyl alcohol fiber is soaked in the chromic acid solution at room temperature for 2.5 hours.

[0044] KMnO can also be used in the step 1) 4 / Sulfuric acid was used as an initiator to graft acrylic acid modification on water-soluble polyvinyl alcohol fiber, KMnO 4 The concentration is 5×10 -3 mol / L, the concentration of sulfuric acid is 0.2mol / L, the concentration of acrylic acid is 0.8mol / L, and the reaction time is 3.0h.

[0045] In the step 1), the water / ethanol solution of methacryloxypropyltrimethoxysilane can also be used to modify the surface of the water-soluble polyvinyl alcohol fiber, and the concentration is 25×10 -3mol / L of dicumyl peroxide as initia...

Embodiment 3

[0049] On the basis of Example 1 and Example 2, the fiber temporary plugging displacement experiment is designed, and the length of the modified polyvinyl alcohol fiber in the step 2) is preferably 6-8 mm.

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Abstract

The invention particularly provides a temporary blocking turnaround fracturing method based on surface modified polyvinyl alcohol fibers. The method comprises the following steps that 1, the surfaces of the water-soluble poly(vinyl alcohol) fibers are modified; 2, fracturing work liquid is prepared; 3, liquid in a shaft is extruded out by and replaced with active water; 4, setting is carried out on a facture packer; 5, prepad fluid is injected, and a major fracture is formed; 6, the water-soluble degradable fiber temporary blocking fracturing liquid is injected into the formed major fracture in a step mode and injected into a stratum to form a new branch fracture; 7, the prepad fluid is injected into the formed new branch fracture, and the length of the fracture is expanded; 8, sand-carrying liquid is injected into the formed new branch fracture in a step mode; 9, the sand-carrying liquid in the shaft is extruded out by and replaced with active water. An old facture or a facture filled with sand is temporarily blocked, the new fractures are made on the original fracture in a certain angle direction, more unused areas of natural fractures and primary fractures are communicated, a new fracture flow leakage system is formed, oil and gas production and the ultimate recovery factor of an oil and gas field are improved, and the aims of restoring the yield of an old well and achieving facture production increase of a new well are achieved.

Description

technical field [0001] The invention belongs to the technical field of downhole operations in oilfield exploration and development, and in particular relates to a temporary plugging diversion fracturing method based on surface-modified polyvinyl alcohol fibers, which is used for improving recovery of low-permeability oil and gas reservoirs. Background technique [0002] Changqing oil and gas field has typical characteristics of low pressure, low permeability and low production. With the deepening of development, the hydraulic fractures of the first type of reservoirs that were fractured in the early stage have failed or become blocked, and the permeability of the original fractures has been greatly reduced or even lost its effect. At the same time, due to insufficient early fracturing scale, or short supporting fractures, or low fracture conductivity, such wells must increase the fracturing scale to continue extending the original fractures, or increase the sand ratio / sand v...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/267C09K8/68C09K8/88
Inventor 孙虎温哲豪张冕池晓明白建文许洪星刘欢罗明良李达扬国威杨燕牛成飞高红平衣德强邝聃
Owner BC P INC CHINA NAT PETROLEUM CORP
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