Device and method for evaluating influence of pressure change on completeness of cement sheath

Abstract

The invention provides a device and a method for real simulation of underground environments, completeness maintaining of experiment equipment, and accurate and omnibearing evaluation of completeness of a cement sheath. The device mainly comprises an upper end cap, a lower end cap, an outer pipe, a middle pipe, the cement sheath, a sleeve pipe, a long source distance sector cement bond logging instrument (SBT (segmented bond tool)) and a high-temperature and high-pressure kettle. The method comprises the following steps of utilizing the high-temperature and high-pressure kettle to simulate the stratum temperature pressure of the curing and forming of the cement sheath; loading and unloading an inner annulus and an outer annulus, so as to simulate the actions of change of well shaft pressure and stratum pressure on the cement sheath under the actual working condition; utilizing a transmitting probe and a receiving probe of the SBT to continuously transmit and receive acoustic wave signals, and performing the omnibearing and high-resolution compensation type attenuation rate measurement, so as to obtain the bonding qualities of a first interface and a second interface of the cement sheath of the well cementing cement sheath under the actual stratum environment, and the amounts, sizes and bearings of cracks and channeling in the cement sheath. The device and the method have the advantage that the underground environment can be really simulated in the omnibearing way, so as to accurately and efficiently evaluate the completeness of the well cementing cement sheath, provide the new method and basis for indoor cement slurry evaluation systems and sites to take the targeted measures, and improve the well cementing quality.

Description

technical field [0001] The invention relates to the field of oil and gas well cementing cement sheath integrity detection, in particular to a device and method for evaluating the influence of downhole pressure changes on cement sheath integrity. Background technique [0002] In the drilling process of oil and natural gas, the purpose of cementing is to seal off the formation, strengthen the wellbore, and establish a flow channel with good sealing performance in the well, so as to ensure the continued safe and efficient drilling, and to ensure the post-operation (oil testing, stimulation operations, etc. ) and normal production. To achieve the above cementing purposes, the cement sheath between the formation and the outer wall of the casing needs to maintain good integrity. Among them, the cementation quality of the first interface (the interface between the cement sheath and the casing) and the second interface (the interface between the cement sheath and the formation) and...

AI Technical Summary

Problems solved by technology

At present, in the field of cement sheath integrity testing, the FMA7150 air channeling evaluation instrument developed by American Kindle Company can simulate the process of cement slurry dehydration and air channeling, but due to the influence of the structure and performance of the instrument, it cannot truly simulate cement The anti-channeling experiment of the ring under the action of high formation pressure and wellbore pressure in the downhole; "a simulation test device for preventing gas channeling in the later stage of cementing" proposed by the domestic CNPC Chuanqing Drilling Engineering Co., Ltd., and the CNOOC proposed "A method for simulating cementing failure caused by pressure changes" and other devices and methods have been improved for the shortcomings of FMA7150, which can simulate the gas channeling experiment of the cement sheath under the action of high formation pressure and wellbore pressure in the downhole

However, the above-mentioned experimental devices and methods still have relatively large limitations: (1) In this method, gas is injected at one end of the cement sheath, and whether gas is detected at the middle position in the height direction of the cement sheath or at the other end of the cement sheath is used as a judgment. Whether there are micro-annulus, cracks, channeling between the cement sheath and the casing, and the criteria for evaluating the integrity of the cement sheath. However, this method can only detect the conditions where the cement sheath has formed a large-scale communication micro-annulus, cracks, and channeling , can not detect uncommunicated micro-annulus, cracks, and channeling; (2) After the gas channeling experiment, the cement sheath needs to be dissected as a whole to analyze whether the cement sheath has cracks at the cross-section. However, this method not only destroys the experimental equipment , and in the dissection process, it is easy to cause the cement sheath to be dissected to induce the development of primary cracks or develop new cracks, thus affecting the accuracy of the test results

[0005] Through the research and analysis of cementing sheath integrity detectors at home and abroad, it is found that the existing detectors can only qualitatively detect the cement sheath has formed large-scale communicating micro-annulus, cracks, and channeling conditions, and cannot be tested in real conditions. Simulate the downhole working conditions, while maintaining the integrity of the experimental equipment, accurately and efficiently quantitatively detect the number, size and orientation of the uncommunicated microannulus, cracks, and channeling of the cement sheath, and the uncommunicated microannulus, cracks, channeling Under a certain downhole environment, it can quickly transform into a large-scale communication micro-annulus, cracks, channeling, thus endangering the quality and safety of the project

Images