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Large-discharge-capacity composite acid fracturing modification method for carbonate reservoir

A technology of composite acid fracturing for carbonate rock reservoirs, applied in chemical instruments and methods, earthwork drilling, and drilling compositions, etc., which can solve the problems of short penetration distance, fast acid rock reaction rate, and corrosion inhibition Weakness and other problems, to achieve long effective distance, reduce reaction rate, improve the effect of diversion capacity

Active Publication Date: 2019-10-29
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The corrosion inhibition effect of these two types of substances is weak, and large-displacement construction cannot be realized, and the acid-rock reaction rate is too fast, the penetration distance of acid or slick water is short, the length of acid-etched fractures is short, and the micro-fractures of the stimulated reservoir Insufficient reconstruction of seepage channels

Method used

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  • Large-discharge-capacity composite acid fracturing modification method for carbonate reservoir
  • Large-discharge-capacity composite acid fracturing modification method for carbonate reservoir
  • Large-discharge-capacity composite acid fracturing modification method for carbonate reservoir

Examples

Experimental program
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Effect test

Embodiment 1

[0062] A large-displacement composite acid fracturing reconstruction method for carbonate rock reservoirs, comprising the following steps:

[0063] Step 1: Obtain the fracture development degree, rock brittleness and horizontal stress evaluation results of carbonate rock reservoir according to the evaluation results of well logging or core experiments, and obtain the carbonate reservoir fracture development degree, rock brittleness and horizontal stress Based on the evaluation results, select reservoirs that can be stimulated with large displacement compound acid fracturing;

[0064] The above-mentioned options can implement large-displacement composite acid fracturing reservoirs, including the following conditions:

[0065] (1) Evaluate the fracture development degree of the reservoir according to well logging or core experiments, and select more than 3 fractures per meter of effective reservoir thickness, with an average fracture length > 20cm;

[0066] (2) Evaluate the bri...

Embodiment 2

[0076] A preferred large-displacement composite acid fracturing method for carbonate reservoirs comprises the following steps:

[0077] Step 1: Obtain the fracture development degree, rock brittleness and horizontal stress evaluation results of carbonate rock reservoir according to the evaluation results of well logging or core experiments, and obtain the carbonate reservoir fracture development degree, rock brittleness and horizontal stress Based on the evaluation results, select reservoirs that can be stimulated with large displacement compound acid fracturing;

[0078] The above-mentioned options can implement large-displacement composite acid fracturing reservoirs, including the following conditions:

[0079] (1) Evaluate the fracture development degree of the reservoir according to well logging or core experiments, and select more than 3 fractures per meter of effective reservoir thickness, with an average fracture length > 20cm;

[0080] (2) Evaluate the brittleness eva...

Embodiment 3

[0118] refer to figure 1 and figure 2 In this example, Well C1 is taken as an example. Well C1 is a gas well in a Lower Paleozoic Ordovician dolomite reservoir in a certain block. / 100m, permeability 0.15-0.36mD, porosity 4.2-6.4%. From the point of view of coring properties, it is mainly dolomite with calcareous powder crystal, a small amount of calcite and mud, and fractures are relatively developed. The well is cemented and completed with 71 / 2 casing, and the fracturing is performed with 2 3 / 8 "The oil pipe is injected from the oil and casing annulus for fracturing. In order to fully stimulate the dolomite reservoir of the well, realize deep acid fracturing, and connect the natural fractures of the reservoir, a large-volume composite acid fracturing stimulation method was designed.

[0119] The specific implementation steps are as follows:

[0120] Step 1: According to the evaluation results of logging or core experiments in Well C1, obtain the carbonate reservoir f...

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Abstract

The invention relates to the technical field of oil-gas field fracturing, in particular to a large-discharge-capacity composite acid fracturing modification method for a carbonate reservoir, and the method reduces the reaction rate of acid liquor and improves the length of acid-etched fractures by adopting multi-stage alternate injection of slickwater, gelled acid and variable-viscosity acid, is beneficial to communicating natural fractures and improves the acid fracturing modification volume of the reservoir; by adopting an earthworm pore acid liquid system, the acid liquid can deeply penetrate in the cracks, a longer effective action distance is formed, and the flow conductivity is improved; resistance reducing acid is adopted in the later stage, so that the acid corrosion degree of thereservoir around a shaft can be enlarged, and the flow conductivity of the reservoir in a near wellbore area is further improved; and the carbonate rock reservoir with relatively developed cracks is subjected to volume acid fracturing, natural cracks of the reservoir can be fully utilized, and the natural cracks are communicated while extended cracks and karst caves are enlarged by means of the corrosion effect of acid liquor on carbonate minerals, so that the flow conductivity of a seepage channel is increased, and the purpose of increasing the yield is achieved to the maximum extent.

Description

technical field [0001] The invention relates to the technical field of fracturing in oil and gas fields, in particular to a large displacement composite acid fracturing reforming method for carbonate rock reservoirs. Background technique [0002] Since carbonate reservoirs are generally buried at a depth of 3200m-4200m, and the temperature and closure pressure are relatively high, acid fracturing for carbonate oil and gas reservoirs faces many difficulties: (1) Reservoirs are medium-low porosity and ultra-low permeability The physical properties of the reservoir are relatively poor; (2) the fractures are relatively developed and unevenly distributed; (3) due to the deep burial and high temperature of the reservoir, the temperature can reach 120°C, resulting in a fast acid-rock reaction speed, which affects the acid erosion of fractures. The extension of the distance makes it difficult to effectively achieve deep penetration, which makes it difficult to effectively communicat...

Claims

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Application Information

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IPC IPC(8): E21B43/27C09K8/74
CPCC09K8/74C09K2208/32E21B43/26
Inventor 牟春国马旭陈宝春白建文马占国贾建鹏何平韩巧荣马新星李树生
Owner PETROCHINA CO LTD
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