Visible evaluation device and method for shale gas well multi-stage fracturing cement sheath air-tight seal integrity

Abstract

The invention belongs to the technical field of petroleum and natural gas engineering shaft integrity and discloses a visible evaluation device and method for shale gas well multi-stage fracturing cement sheath air-tight seal integrity A full process of crack initiation, expansion and connection of a cement sheath after shale gas well multi-stage fracturing is simulated; a visible evaluation leakage channel is quantified and leakage speed rate is calculated; and a basis for shale gas well multi-stage fracturing parameter optimization and cement mortar performance design can be provided. The visible evaluation device is simply structured and easy to operate; the process of crack initiation, expansion and connection of the interior and the gluing surface of cement sheath after shale gas well multi-stage fracturing can be simulated and visible description can be conducted; the visible leakage channel can be led to CFD software and gas leakage speed can be calculated; with a combination of a leakage detection device, reliability of a test result can be verified; a theoretical basis can be provided for the shale gas well multi-stage fracturing parameter optimization and cement mortar performance design; and low labor intensity, short time consumption and high work efficiency can be achieved.

Description

technical field [0001] The invention belongs to the technical field of oil and natural gas engineering wellbore integrity and safety, and in particular relates to a visual evaluation device and method for multi-stage fracturing of shale gas well cement ring gas seal integrity. Background technique [0002] The development of shale gas generally requires the combination of horizontal well drilling and multi-stage fracturing technology to increase single well production. During multi-stage fracturing, the cement sheath of shale gas wells will continuously withstand the cyclic load of casing internal pressure and wellbore temperature changes, resulting in micro-cracks or micro-annulus in the cement sheath. As the multi-stage fracturing operation proceeds, micro-fractures and micro-annulus are continuously generated and developed, eventually forming a continuous channel for gas leakage, which affects the safety of shale gas wells. At present, theoretical modeling and experiment...

AI Technical Summary

Problems solved by technology

[0003] However, the existing experimental devices and methods for evaluating the integrity of the cement sheath can only qualitatively evaluate the sealing performance of the cement sheath under load from a macroscopic perspective, but cannot analyze the occurrence of micro-cracks or micro-annulus in the cement sheath during the whole process of multi-stage fracturing. Therefore, it is difficult to quantitatively reveal the mechanical mechanism of cement sheath seal failure during repeated fracturing, nor can it better guide the optimization design of fracturing construction parameters and cement sheath mechanical parameters.

Images