Method for volume acid-fracturing reformation of seam net of carbonate reservoir

A carbonate reservoir and fracture network technology, applied in chemical instruments and methods, mining fluids, earthwork drilling and production, etc., can solve problems such as heavy workload and coordination difficulty on site, collapse of overlying strata structure, short circuit of fracture channels, etc. , to achieve the effect of retarding the acid rock reaction, developing the fracture system, and reducing the wellhead pressure

Inactive Publication Date: 2017-09-29
RES INST OF SHAANXI YANCHANG PETROLEUM GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this acid fracturing process still has the defect that fracture closure leads to short-circuit of fracture channels, which affects production increase; moreover, there are many types of acid liquids prepared on site, resulting in relatively large workload and coordination difficulties on site, and complicated construction procedures; in addition, in horizontal wells During the staged acid process in the horizontal section, a large amount of gelled acid or cross-linked acid is used, which may easily cause the structure of the overlying strata to loosen and collapse, and there is a risk of deformation of the cementing casing

Method used

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  • Method for volume acid-fracturing reformation of seam net of carbonate reservoir
  • Method for volume acid-fracturing reformation of seam net of carbonate reservoir
  • Method for volume acid-fracturing reformation of seam net of carbonate reservoir

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] The low-viscosity drop-resistance slick water acid liquid is configured, and the configuration method is as follows: weigh each raw material component according to weight percentage, when the acid used is hydrochloric acid, formic acid or acetic acid, first dilute the acid, and then add it to water; when the acid When it is a biological acid, it does not need to be diluted, and it can be directly added to water. After stirring, sequentially add alkyl quaternary ammonium salt, sodium ascorbate, emulsion corrosion inhibitor, citric acid, and drainage aid, and stir for 2-5 minutes to prepare low Viscosity reduction slippery water acid.

[0036] The specific implementation formula of described low-viscosity drop resistance slippery water acid solution is as follows:

[0037] 1. A low-viscosity drop-resistance slick water acid solution, consisting of the following raw material components in weight percent (total amount 100%): hydrochloric acid 5%, dodecyltrimethylammonium ch...

Embodiment 2

[0051] 1. A method for volumetric acid fracturing of a carbonate reservoir fracture network, comprising the following steps:

[0052] (1) Inject low-viscosity slick water acid fluid, and add proppant for slugging, the number of slugging is not less than 3 times, and carry out fracture network volume fracturing reconstruction for micro-fractures in the reservoir;

[0053] (2) Inject water-based sand-carrying fracturing fluid to form sand-filled fractures with a fracture length of not less than 120 meters on both sides of the wellbore;

[0054] (3) Inject displacement fluid, shut down the well for 0.5h, and then open the well to drain the fluid and test the oil and gas production;

[0055] Wherein, the low-viscosity-reducing slippery water acid solution described in step (1) is composed of the following raw material components in weight percentage: acid 5-20%, alkyl quaternary ammonium salt 1-3%, sodium ascorbate 0.5-2% , emulsion corrosion inhibitor 0.1-0.5%, citric acid 0.5-1...

Embodiment 3

[0066] Well Y is a Permian carbonate rock gas test well in a certain block. The lithology of the acid fracturing section is white calcite fracture filled limestone. MPa / 100m, permeability 0.1-0.4mD, porosity 5.81-6.8%, core acid erosion test found that the core acid erosion rate is greater than 95%, from the perspective of core physical properties, mainly limestone and a small amount of calcite and mud , reacts violently with dilute hydrochloric acid, the sediment is muddy, and the cracks are relatively developed.

[0067] The acid fracturing scheme design and on-site construction were carried out by adopting the volumetric acid fracturing reconstruction method of carbonate reservoir fracture network provided by this patent.

[0068] The specific implementation method is:

[0069] 1. Construction scale

[0070] See Table 2.

[0071] Table 2 Construction scale and parameters

[0072]

[0073] 2. Low-viscosity slippery water acid formula

[0074] A low-viscosity drop-res...

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Abstract

The invention provides a method for volume acid-fracturing reformation of a seam net of a carbonate reservoir. The method specifically comprises the following steps: (1) injecting low-viscose resistance-reducing sliding acid liquor, performing plunger injection for at least three times and performing volume fracturing reformation of the seam net; (2) injecting a water-based sand-carrying fracturing fluid and forming sand-filling cracks in length not less than 120 meters on the two sides of a well shaft; (3) injecting a displacement fluid, closing the well and then draining the liquid, wherein the low-viscose resistance-reducing sliding acid liquor is composed of 5-20% of acid, 1-3% of alkyl quaternary ammonium salt, 0.5-2% of sodium ascorbate, 0.1-0.5% of emulsion corrosion inhibitor, 0.5-1% of citric acid, 1-3% of discharge aiding agent and the balance of water; the emulsion corrosion inhibitor is selected from any one of polypropylene glycol emulsion, polyvinylpyrrolidone emulsion, acrylamide and 2-crylic acid-2-methallyl sulfonate copolymer emulsion; and the acid is selected from hydrochloric acid, formic acid, acetic acid or bionic acid. The method is simple in construction, the flow conductivity of the seam net is high and the yield-increasing effect is excellent.

Description

technical field [0001] The invention belongs to the technical field of oil field acidification, and in particular relates to a method for volumetric acid fracturing of fracture networks in carbonate reservoirs. Background technique [0002] The exploration area of ​​lower Paleozoic carbonatite reservoir in Yanchang is about 2.0×10 4 km 2 , is the focus of exploration and development of Yanchang Oilfield in recent years, the main purpose is to increase natural gas production. Carbonate reservoirs are especially suitable for volumetric acid fracturing of fracture networks. With the help of the acid’s dissolution of carbonate minerals, while expanding and extending fractures and caves, the conductivity of seepage channels is increased, and more oil and gas seepage channels are communicated and connected. and oil storage space to achieve the purpose of maximizing production increase. Among them, the dissolution distance of the acid solution, the distribution and intensity of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/74C09K8/68E21B43/27E21B43/267
CPCC09K8/685C09K8/725C09K8/74C09K8/90E21B43/26E21B43/267
Inventor 李彦林梁晓兵武骞迟立宾周伟勤张锋三杨洪景丰白方林
Owner RES INST OF SHAANXI YANCHANG PETROLEUM GRP
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