Shale gas horizontal well refracturing technological process and design method

Abstract

The invention provides a shale gas horizontal well refracturing technological process and a design method. The steps of refracturing selected region well fixation, refracturing engineering design, refracturing field implementation and refracturing monitoring and after-fracturing evaluation are included. According to the shale gas horizontal well refracturing technological process and the design method, reasonable and accurate evaluation analysis after construction can be guaranteed, the shale gas reservoir fracturing stimulation work effect can be successfully improved, the productivity and recovery ratio of a gas well are increased, and the shale gas exploitation process is further accelerated.

Description

technical field [0001] The invention relates to the technical field of unconventional oil and natural gas production stimulation, in particular to a technical process and design method for repeated fracturing of shale gas horizontal wells. Background technique [0002] Shale gas reservoirs are typical unconventional natural gas reservoirs with low permeability and low porosity, which account for a large proportion of my country's oil and gas resources. Hydraulic fracturing technology, as the main measure to increase production and injection of unconventional oil and gas wells, has been widely used in the development of shale gas fields. However, after the actual shale gas horizontal well stimulation, due to poor drilling operation, improper selection of the target stimulation layer, or casing abnormality due to wellbore damage, the segment was lost, or it was limited by the fracturing technology and construction materials at that time. Affected by many operational factors s...

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Problems solved by technology

[0017] Specific to the domestic shale field, many difficulties need to be overcome to complete the refracturing of such wells as follows: (1) The horizontal section is long, most horizontal wells are 1500-2000m in length, the horizontal section is long, the number of stages is large, and the scale of measures large, the construction period is relatively long, and higher requirements are required for the plugging performance of temporary plugging and steering materials, while the coiled tubing spanning system puts forward higher requirements for oil connection, and at the same time, the horizontal section is too long, there are many holes, and the liquid The fluid loss is large, and it may be difficult to start the pressure at the initial stage; (2) Due to the possible deformation of the casing and the complicated wellbore conditions caused by drilling debris, the cost of squeezing cement and secondary cementing is high and the operation period is long, so mechanical tools are used. There are safety risks in the means of achieving spanning, and the initial pressure does not meet wells with complex wellbores, and deformation may occur in later production; (3) natural fracture zones or pressure depletion areas may strongly induce refracturing fractures, so for depletion The treatment and diversion of regional and natural fractures put forward higher requirements on the performance of temporary plugging materials; (4) The strong heterogeneity of the horizontal section itself and the large stress difference may increase the difficulty of fracture diversion. It is difficult to optimize the parameters; (5) It is necessary to accurately characterize the gas production profile in the horizontal section, determine the gas production contribution well section and invalid perforations, and determine the hole repair section and the key reconstruction well section, etc.

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