Simulated evaluation device for well-drilling plugging of stress sensitivity stratum

Abstract

The invention discloses a simulated evaluation device for well-drilling plugging of a stress sensitivity formation. The device comprises a simulated pit shaft, wherein the side wall of the simulated pit shaft is fixedly provided with a plurality of simulated lost-circulation formation devices communicated with the simulated pit shaft; each simulated lost-circulation formation device is composed of a sample carrier and a solid core sample arranged in the sample carrier, one end of the sample carrier is communicated with a thru hole at the side wall of the simulated pit shaft, and the other endof the sample carrier is provided with a through hole; the two ends of the solid core sample are arranged respectively corresponding to the thru hole and the through hole; a sealed confining pressurecavity is formed between the circumferential surface of the solid core sample and the inner wall of the sample carrier, and the confining pressure cavity is communicated with a hydraulic pressure stabilization source by a pipeline; and one end of the simulated pit shaft is provided with a plugging slurry inlet, and the other end of the simulated pit shaft is provided with a plugging slurry outlet, the plugging slurry inlet is communicated with a slurry pump, and the plugging slurry outlet is communicated with the slurry pump by a pipeline, thereby forming a circulatory flow of plugging slurry. The device provided by the invention provides a theoretical basis for the studies on plugging processes of stress sensitivity formations and the plugging effects of different plugging materials.

Description

technical field [0001] The invention relates to a simulation evaluation experiment system for drilling plugging, in particular to a simulation evaluation device for drilling plugging in stress-sensitive formations. Background technique [0002] Many large and medium-sized oil and gas fields in piedmont structural belts in western my country, due to the extremely developed fractures and pores and the existence of high and steep structures, show typical drilling characteristics of stress-sensitive formations, resulting in frequent well loss during actual drilling. Accidents such as pipe sticking and overflow and other complicated situations are caused, and the pressure balance is extremely difficult to adjust, which seriously restricts the development of the oil field. [0003] Currently used drilling plugging evaluation devices mainly use rigid cutting seal plates of different widths and steel balls of different sizes to simulate fractured and pore-type lost formations, add pl...

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Problems solved by technology

[0004] (1) The existing plugging evaluation device cannot realize the circulation of plugging slurry (liquid), which will lead to the deposition of plugging materials at the bottom of the simulated wellbore, reducing the effect of plugging evaluation

[0005] (2) Existing leak plugging evaluation devices can only simulate fractures with uniform width, which is far from real fractures; even if some experimental devices use artificial cores to simulate leakage zones, they cannot fully satisfy the parameter characteristics of real cores

[0006] (3) The existing plugging devices do not study the influence of stress sensitivity on the plugging effect by applying confining pressure to the core. Since the actual lost formations in the western region are all in the deep formations of several kilometers, the plugging materials The evaluation results will be quite different from the actual plugging situation on site

[0007] (4) At present, all leakage evaluation devices use a single leakage channel for experimental research, but the actual leakage formation is composed of multiple leakage channels. Therefore, the existing structure cannot be used to simultaneously plug multiple leakage channels Leakage Research and Evaluation

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