Method for evaluating failure strength of well cementation first and second cemented surfaces under dynamic load

Abstract

The invention discloses a method for evaluating the failure strength of well cementation first and second cemented surfaces under the dynamic load. The method comprises the steps that (1) a rock-cement stone-sleeve composite structure sample is manufactured; (2) the sample is horizontally clamped between a Hopkinson rod incident rod and an output rod, a conical punch impacts the incident rod to generate incident waves, after passing through the sample, the incident waves generate reflected waves and projected waves, dynamic strain signals of the incident waves, the reflected waves and the projected waves are recorded by a strain gauge, the dynamic strain signals are converted into electrical signals to be transmitted to a computer, the process and the corresponding time point from failurestarting to a final complete failure of the first and second cemented surfaces are recorded by a high-speed photographic instrument, a strain rate time travel curve and a stress-strain curve are obtained by the computer, and the corresponding failure strength is obtained by analyzing the curve peak points. Impact of formation perforation and subsequent operation such as acidizing fracturing on cement rings and sleeves can be truly simulated, and meanwhile the failure strength capable of being borne by the first and second cemented surfaces under the dynamic load is evaluated.

Description

technical field [0001] The invention relates to the field of oil and gas well cementing, and specifically provides a method for evaluating the failure strength of the first and second cemented surfaces of cementing, which can simulate the impact force of a cement sheath caused by dynamic loads caused by perforation and subsequent operations. The failure process of the first and second cemented surfaces, evaluate the strength of the simultaneous failure of the first and second cemented surfaces under dynamic load. technical background [0002] Cementing engineering is an important link in drilling operations and the key to ensuring the normal follow-up operations downhole. [0003] For oil and gas wells, the most common failure phenomenon is the failure of the cement interface. The cementation surface is divided into one interface and two interfaces. The interface formed by the cement stone and the casing is the first interface, and the interface formed by the cement stone a...

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Problems solved by technology

[0009] Third, although the loading load and the first and second interfaces are taken into account, the test cannot be carried out in batches, and the dynamic load simulation test process is too complicated and the operation is not easy

For example, Tang Kai, the logging company of Chuanqing Drilling Engineering Co., Ltd., and others have developed a perforation simulation device. Although it can simulate perforation operations, it is not conducive to single-person testing and will cause great damage to the mold. Dynamic test equipment such as drop hammers and impact guns, Neither can achieve constant load loading, and the equipment is complicated and the operating cost is high

[0010] These research methods all try to simulate the real stress state of the cement sheath in downhole working conditions, but due to the limitations of experimental equipment and conditions, they seldom consider the impact of the cement sheath and casing on the downhole stimulation operations such as perforation, acid fracturing, etc. The dynamic impact loads that came from the cement sheath did not make a quantitative evaluation of the damage to the bond strength of the first and second interfaces of the cement sheath.

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