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Pad-acid solution and acid pretreatment method for horizontal well fracturing of deep shale gas

A technology of acid pretreatment and pre-acid, which is applied in chemical instruments and methods, earthwork drilling, wellbore/well components, etc. It can solve the problems of small number of liquid inlet holes, excessive corrosion of casing, mud plugging, etc. Achieve good fracturing construction effect, convenient operation, and reduce construction pressure

Active Publication Date: 2017-12-08
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The composition and ratio of the pre-acid solution in the present invention solve the problems of mud blockage, few liquid inlet holes, excessive corrosion of pipe sleeves, hydration expansion of clay minerals, and liquid stagnation in the formation as a whole.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] In this embodiment, a deep shale gas pilot test well in a certain block of an oilfield is taken as an example for illustration. The depth of the construction well section is 4382-4411m, the average clay mineral content is 33.2%, the quartz content is 55.3%, and the carbonate rock is 5.4-9.3%. Sensitivity experiments in adjacent areas show that there are moderately strong water sensitivity and strong acid sensitivity, but no velocity sensitivity. In this embodiment, the pre-acid solution includes 16.5 parts by volume of earth acid, 2 parts by volume of high-temperature corrosion inhibitor, 1.5 parts by volume of iron ion stabilizer, 1 part by volume of viscoelastic surfactant, and the rest is water. Among them, earth acid includes HCl and HF, and the mass ratio of HCl and HF is 10:1; the viscoelastic surfactant is a conventional viscoelastic surfactant, such as quaternary ammonium salt cationic surfactant, betaine or amine oxide type amphoteric One or more of surfactants...

Embodiment 2

[0026] The application environment of this embodiment is that the horizontal wellbore runs through the top of the reservoir, and various storage performances are in an environment where the lower part of the horizontal wellbore is better. In the present embodiment, the pre-acid solution includes 16.5 parts by volume of earth acid, 2 parts by volume of high temperature corrosion inhibitor, 1.5 parts by volume of iron ion stabilizer, 1 part by volume of viscoelastic surfactant and 1.5 parts by volume (volume Part is the bromide salt of 1~2 all can implement), all the other are water. Wherein, bromide adopts sodium bromide, and bromide can also be substituted by nitrate (using sodium nitrate). The acid pretreatment method for deep shale gas horizontal well fracturing in this embodiment is the same as that in Embodiment 1 above.

[0027] According to the above-mentioned pre-acid liquid ratio and injection steps, the test well and each section were fracturing, so that the acid liq...

Embodiment 3

[0029] The application environment of this embodiment is an environment where the horizontal wellbore runs through the top of the reservoir, and the various storage performances are better in the lower part of the horizontal wellbore, and the acid liquid cannot be aggravated. The pre-acid solution in this embodiment is the same as that in Embodiment 1, and the acid pretreatment method for fracturing a deep shale gas horizontal well is basically the same as that in Embodiment 1 above. The difference is that before the pre-acid fluid is injected, all the liquid in the wellbore of the horizontal well is circulated out of the ground; after the pre-acid fluid front reaches the borehole, the acid fluid discharge is controlled at 0.2m 3 / min until all the acid liquid is pumped into the wellbore.

[0030]According to the above-mentioned pre-acid liquid ratio and injection steps, the test well and each section were fracturing, so that the acid liquid migrated close to the bottom of the...

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Abstract

The invention provides a pad-acid solution and acid pretreatment method for horizontal well fracturing of deep shale gas. The pad-acid solution comprises, by volume, 10 to 20 parts of mud acid and 1 to 10 parts of an additive, wherein the additive is at least one selected from the group consisting of a viscoelastic surfactant, a corrosion inhibitor, an anti-swelling agent, a stabilizer and a cleanup additive. The acid pretreatment method comprises a step of injecting the above pad-acid solution, wherein before the front edge of the pad-acid solution enters a perforation blast hole, normal pump casting is carried out on the pad-acid solution, and after the front edge of the pad-acid solution reaches the blast hole, the output volume of the pad-acid is reduced. The pad-acid solution and acid pretreatment method provided by the invention can effectively reduce construction pressure, strengthen acid-rock reaction, control the form of crack propagation and improve the effect of multi-stage fracturing.

Description

technical field [0001] The invention relates to the technical field of petroleum exploitation, in particular to a pre-acid liquid and an acid pretreatment method for deep shale gas horizontal well fracturing. Background technique [0002] With the development of exploration and development technology, the exploration and development of medium and shallow shale gas reservoirs have gradually matured, and the development of deep shale gas has entered the stage of exploration and testing. At present, among the deep shale gas blocks with a depth of more than 3500m discovered by exploration, the single-well production after fracturing in three deep shale gas blocks with a vertical depth of 3500-4100m, including Haynesville, Eagle Ford (dry gas) and Cana Woodford (gas), 5×10 4 m 3 / d or more, the single well recovery is as high as 100 million cubic meters or more, which has economic development prospects. The development of deep shale gas has brought many challenges to the exist...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/72E21B37/06E21B33/138E21B43/27
CPCC09K8/72E21B33/138E21B37/06E21B43/26
Inventor 蒋廷学苏瑗王宝峰刘建坤魏娟明黄静
Owner CHINA PETROLEUM & CHEM CORP
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