Multi-crack fracturing control method for medium-depth coal beds

Abstract

The invention relates to an oil extraction process for oil fields, in particular to a multi-crack fracturing control method for medium-depth coal beds. The method comprises six steps of 1) preparation of a filtrate reduction fracturing fluid; 2) utilization of a high-pressure pump set; 3) utilization of a high-pressure pump set; 4) utilization of a high-pressure pump set; 5) phased utilization of a prepad liquid; and 6) ending of work. According to the multi-crack fracturing control method, prior conventional active-water sand fracturing method is changed through theoretical analysis and on-site verification, and the filtrate reduction fracturing fluid, the prepad liquid variable displacement technology, a multi-stage particle size slug technology, a reasonable mortar-sand ratio raising technology and the like are used, accordingly, difficulties such as large filter losses, poor sand carrying capabilities and excess leak-off of the fracturing liquid and high construction pressure during opening of natural cracks are overcome. Multi-crack is effectively prevented and treated through the means of the filtrate reduction fracturing fluid, and the prepad liquid variable displacement technology and the multi-stage particle size slug technology, so that the construction pressure is reduced, smooth adding of a propping agent is guaranteed, and the fracturing construction success rate is improved.

Description

technical field [0001] The invention relates to a process method for oil recovery in an oil field, in particular to a controlled multi-fracture fracturing method for medium-deep coal seams used in underground coal seam operations. Background technique [0002] Medium-deep coal seams are usually fractured with conventional active water and sand. The scale of sand addition is small and the sand ratio is low. Due to the large amount of active water filtration and poor sand-carrying capacity, natural fractures have excessive filtration of fracturing fluid and construction pressure. Difficulties such as high height and difficulty in adding sand. The success rate of construction using active water is low, and the expected production increase effect cannot be achieved. Contents of the invention [0003] The object of the present invention is to provide a method for controlling multiple fractures in medium-deep coal seams that can effectively prevent and control multiple frac...

AI Technical Summary

Problems solved by technology

[0002] Medium-deep coal seams are usually fractured with conventional active water and sand. The scale of sand addition is small and the sand ratio is low. Due to the large amount of active water filtration and poor sand-carrying capacity, natural fractures have excessive filtration of fracturing fluid and construction pressure. Difficulties such as high height and difficulty in adding sand

The success rate of construction with active water is low, and the expected production increase effect cannot be achieved

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