Entrance ability evaluation device and evaluation method for well-cementing cement sheath micro-crack plugging agent

Abstract

The invention discloses an entrance ability evaluation device and evaluation method for a well-cementing cement sheath micro-crack plugging agent. The evaluation device comprises a kettle body, an injection pump, an annular pressure pump, a pressure pump and a heating control device. A circular-ring-shaped rubber sleeve, an artificially-cracked cement plunger and a columnar sandstone core are arranged in the kettle body; shallow grooves are formed in the centers of an upper end socket and a lower end socket; and sealing rings are arranged to seal the two ends of the kettle body. A plugging agent is injected from the upper end to simulate the underground blocking cement sheath micro-crack work. With the device, the underground high temperature environment can be simulated; and the pluggingagent is used for realizing blocking in the micro crack. The pressure pump applies the pressure to squeeze the plugging agent into the cement plunger with the artificially made crack; and the capability of the plugging agent entrance and stay in a cement sheath micro crack, the blocking quality and influence on the blocking of the well-cementing cement sheath micro-crack by the plugging agent by the squeezing pressure, and the blocking effects of the plugging agent in the cement plungers with different artificial crack lengths are studied.

Description

technical field [0001] The invention relates to an evaluation device and method for simulating the ability of a plugging agent to enter micro-cracks in a cement sheath. The invention belongs to the field of oil and gas well engineering well cementing. Background technique [0002] Well cementing is the construction operation of running casing into the well and injecting cement into the annular space between the wellbore and the casing to protect and support the casing in the oil and gas well and to isolate the oil, gas, and water layers. One of the key technologies for subsequent safe drilling and long-term mining. The main function of the cement is to seal the annular space between the casing and the host formation against fluid flow along the wellbore. The cement also protects the casing from corrosion, making the wellbore more structurally sound. [0003] The cement sheath refers to the cement stone formed by the cement slurry in the annular space. After the cementing ...

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Problems solved by technology

[0004] At present, there is a lack of devices capable of conducting this research. Yang Zhenjie et al. proposed a simulation evaluation tester for the integrity of the cement sheath (Yang Zhenjie, Astou Gawane, Yang Qiang, et al. Simulation of micro-gap and micro-cracks in cement sheath Test method [J]. Natural Gas Industry, 2015, 35(9).), this device can simulate the process of downhole pressure changes that damage the oil well cement sheath and form micro-cracks, so as to measure the channeling strength of the cement sheath under different conditions However, this device cannot study the plugging ability of the plugging agent injected into the micro-cracks after the formation of micro-cracks

[0005] Bu Yuhuan (Bu Yuhuan, Yu Liguo, Wang Chunyu, et al. Evaluation method for self-healing performance of cement stone[J]. Laboratory Research and Exploration, 2015,34(7):17-21.) proposed a self-healing performance of cement stone The evaluation device, which takes the plugging pressure as the index, analyzes the influence of the amount of self-healing material in contact with oil and the size of the crack on the self-healing performance of cement stone through experiments, and proves that the evaluation device and evaluation method are effective in evaluating the self-healing performance of cement stone. Feasibility, but the device can not achieve the maintenance of artificial micro-cracks on the cement plunger

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