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A carbon dioxide acid fracturing method for low-permeability heterogeneous carbonate gas reservoirs

A carbonate rock and carbon dioxide technology, applied in earthwork drilling, wellbore/well components, and production fluids, etc., can solve the problems of high reaction rate of acid rock, difficulty in flowback after fracturing, and large amount of acid liquid, etc., to achieve Improve the effective distance, adapt to environmental protection, and reduce the effect of reservoir damage

Active Publication Date: 2021-12-14
SHAANXI YANCHANG PETROLEUM GRP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] There are four problems in the conventional acid fracturing method widely used at present: first, acid liquid is used for construction in the whole process. Filtration loss is out of control, resulting in extremely low efficiency of acid fluid fracture creation, making it difficult to form deep penetrating complex fracture networks, and unable to effectively communicate with oil and gas enriched areas; second, unilaterally increasing acid fluid viscosity to reduce fluid loss, and causing difficulties in flowback after fracturing , a large amount of high-viscosity acid fluid stays in the formation, causing reservoir damage; third, the acid-rock reaction rate is high, a large amount of acid fluid is consumed in the fracture near the wellbore and loses its activity, and the effective action distance of the acid fluid is limited so that it cannot act in the deep part of the fracture to form an effective seepage channel; Fourth, the amount of acid solution is large, which is not conducive to environmental protection

Method used

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  • A carbon dioxide acid fracturing method for low-permeability heterogeneous carbonate gas reservoirs

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] A carbon dioxide acid fracturing method for low-permeability heterogeneous carbonate gas reservoirs, comprising the following steps:

[0030] (1) CO 2 Tank car, CO 2 The pump truck and the fracturing truck A are sequentially connected to the wellhead in series, and the CO 2 The tank car is filled with liquid CO 2 ;

[0031] (2) Connect the liquid tank, acid tank A and acid tank B directly to the low-pressure manifold, the liquid tank is filled with slippery water, acid tank A is equipped with drag-reducing acid, and acid tank B is equipped with diverting acid;

[0032] (3) Connect the low-pressure manifold, sand mixing truck, fracturing truck B and high-pressure manifold to the wellhead in series;

[0033] (4) at 1.0-1.5m 3 / min displacement pump injection 10.0-30.0m 3 Antihypertensive acid;

[0034] (5) at 1.5-3.0m 3 / min displacement pump injection 100.0-300.0m 3 liquid carbon dioxide;

[0035] (6) at 3.0-8.0m 3 / min displacement pump injection 80.0-200.0m ...

Embodiment 2

[0041] On the basis of Example 1, in step (9), the liquid volumes of water slide, drag-reducing acid, and diverting acid repeatedly pumped were higher than the previous operation; the CO 2 There are multiple tank cars, all of which are directly connected to the CO 2 The pump truck is connected. There are multiple liquid tanks, acid tanks A, and acid tanks B, and they are all directly connected to the low-pressure manifold; there are multiple fracturing trucks A and connected in parallel; there are multiple fracturing trucks B and they are connected in parallel connection; its ground equipment layout is as follows figure 1 shown.

Embodiment 3

[0043] On the basis of Example 2, the carbonate reservoir of the Lower Paleozoic Majiagou Formation in Well X was modified. The target layer of the carbonate reservoir in Well X was the Lower Paleozoic Majiagou Formation. 3965.5-3981.5m, the effective thickness of the stimulated section is 13.5m, concentrated perforation is carried out near the upper part of the reservoir 3970.0-3972.0. Design liquid carbon dioxide 150.0m 3 , acid-reducing acid 460.0m 3 , slippery water 380.0m 3 , Steering acid 170.0m 3 ;

[0044] The acid pressing method is as follows:

[0045] The pumping steps of carbon dioxide acid fracturing construction designed by the present invention are as follows:

[0046] (1) at 1.0m 3 / min displacement pump injection 20.0m 3 Antihypertensive acid;

[0047] (2) at 1.5m 3 / min displacement pump injection 150.0m 3 liquid carbon dioxide;

[0048] (3) at 3.5m 3 / min displacement pump injection 80.0m 3 slippery water;

[0049] (4) at 3.0m 3 / min displacem...

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Abstract

The invention discloses a carbon dioxide acid fracturing method for low-permeability heterogeneous carbonate gas reservoirs, which includes the following steps: (1) CO 2 Tank car, CO 2 The pump truck and fracturing truck A are connected to the wellhead in series; (2) Connect the liquid tank, acid tank A, and acid tank B directly to the low-pressure manifold; (3) Connect the low-pressure manifold, sand mixing truck, fracturing truck B and The high-pressure manifold is connected to the wellhead in series; (4) at 1.0‑1.5m 3 / min displacement pump to reduce resistance acid; (5) at 1.5‑3.0m 3 / min displacement pumping CO 2 ;(6) at 3.0‑8.0m 3 / min displacement to pump slippery water; (7) at 3.0‑8.0m 3 / min displacement pumping acid-reducing acid; (8) at 2.0‑6.0m 3 / min displacement to pump steering acid; (9) Repeat steps (6)-(8) 0-2 times, repeat (6)-(7) once; (10) Pump slippery water. The method can improve the acid fracturing effect and increase the daily gas production.

Description

technical field [0001] The invention belongs to the technical field of oil and gas field reservoir transformation, and in particular relates to a carbon dioxide acid fracturing method for low-permeability heterogeneous carbonate rock gas reservoirs. Background technique [0002] With the continuous deepening of domestic exploration and development of oil and gas reservoirs, the physical properties of oil and gas reservoirs are getting worse and tighter. Especially for low-permeability heterogeneous carbonate gas reservoirs, acid fracturing (acid fracturing) is an effective measure for the commissioning and stimulation of oil and gas wells. It reacts chemically with the artificial (natural) fracture wall rock through the acid liquid to form groove-like or uneven high-permeability channels, thereby improving the seepage condition of the gas well and increasing the production of the gas well. [0003] In recent years, many domestic oil and gas fields have carried out research ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/27
CPCE21B43/26E21B43/164
Inventor 高瑞民郭建春刘超王香增申峰王念喜苟波刘刚吴金桥马中国乔红军梁小兵李彦林张鸿超刘安邦强腾周隆超
Owner SHAANXI YANCHANG PETROLEUM GRP
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