Acid-fracturing method for leading crack to extend downward

A technology of acid pressure and pressure measurement, which is applied in earth-moving drilling, production of fluids, wellbore/well components, etc., to avoid the effect of re-tracking

Active Publication Date: 2012-11-14
PETROCHINA CO LTD +1
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  • Summary
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Problems solved by technology

[0003] At present, there is no effective technology for acid fracturing of carbonate reservoirs at home and abroad to force the acid fracturing fractures to extend downward. In view of the deficiency of the existing acid fracturing technology for low-permeability carbonate reservoirs, the comprehensive fracture downward acid fracturing Technical requirements, the acid fracturing process must have: firstly, a barrier layer is formed on the upper part of the acid fracturing fractures to control the upward extension of the acid fracturing fractures; second, the acid fracturing fractures are forced to extend downwards

Method used

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Embodiment

[0025] Embodiment: The acid fracturing method of the invention, which uses high-strength and low-density hollow glass microspheres to force the acid fracturing fractures to extend downward to communicate with the underlying reservoir body, was implemented in Well A of the Lungu Oilfield in the Tarim Basin. Limestone reservoirs in the Tarim Oilfield are widely distributed, accounting for about 40% of Tarim's reserves. The reservoirs are buried deep, 5000-7400m, with high closure pressure, greater than 80MPa, and high temperature, 120°C-170°C, with strong heterogeneity. Qualitatively, the matrix permeability is very low (<0.1mD), the average porosity is about 1%, and good reservoirs are all developed with large natural fractures and caves. Due to the limitations of drilling technology and geological conditions, the drilled wellbore (such as some sidetracked wells) is often above the reservoir body, and the distance from the reservoir body is relatively long (generally 50-70m), an...

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Abstract

The invention relates to an acid-fracturing method for leading a crack to extend downward. The acid-fracturing method comprises the following steps: injecting 5-20m3 of hydrochloric acid with the concentration of 10-20 percent into a formation at discharge capacity of 0.5-3.0m3 / minute; injecting 20-100m3 of gel into the crack of the formation at discharge capacity of 1.5-5.0m3 / minute, and then adding ammonium persulfate gel breaker with the concentration of 0.2 percent; pump-injecting 30-80m3 low-concentration carrying fluid with the volume content of hollow glass beads of 2-10 percent at discharge capacity of 1.0-4.0m3 / minute; pump-injecting 50-200m3 gel into the formation at discharge capacity of 3.0-7.5m3 / minute; pump-injecting 50-200m3 gel acid, temperature control various mucic acid into the formation at discharge capacity of 3.0-7.5m3 / minute; using quick water to jack the fracturing fluid in a shaft into the formation; and reaching a long-distance reservoir body which can not becommunicated by the conventional acid-fracturing method and realizing the purpose of directional and deep acid-fracturing modification.

Description

technical field [0001] The invention relates to an acid fracturing method which uses high-strength and low-density hollow glass microspheres to prevent acid fracturing cracks from extending upward and force the acid fracturing cracks to extend downward. Background technique [0002] Carbonate oil and gas reservoirs in my country are widely distributed and have a large amount of resources. Carbonate reservoirs have strong heterogeneity and deep burial (4000-7400m). Acid fracturing technology is one of the effective methods for stimulation of oil and gas wells in carbonate reservoirs. The stimulation effect of acid fracturing in carbonate reservoirs mainly depends on the acid-etched high-conductivity fractured communication reservoirs (mainly large fracture-vug systems). Due to the limitations of drilling technology and geological conditions, the wellbore (such as some sidetracked wells) is often above the reservoir body, and the distance from the reservoir body is relativel...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/27
Inventor 周福建刘玉章刘雄飞熊春明张福祥杨贤友沈建新李向东连胜江石阳贾新峰
Owner PETROCHINA CO LTD
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