固井水泥环微间隙与微裂缝的模拟试验方法

对于固井水泥环微间隙和微裂缝模拟试验方法以及自修复评价试验方法,目前尚未统一。为了顺利开展固井水泥环自修复技术研究,基于大量的探索实验,提出了两种模拟微间隙和微裂缝的试验方法:使用不锈钢钢管模拟套管,通过先在套管内壁涂抹均匀的钻井液液膜,然后灌入固井水泥浆的方法模拟固井水泥环微间隙;通过直接灌入水泥浆(内壁无钻井液液膜),待试样固化后再对钢管外壁施加机械挤压力的方法模拟固井水泥环的微裂缝。从抗窜强度测试、试验误差分析和无损伤CT扫描等方面,对模拟试验方法的可靠性、稳定性和模拟样品的微观形态进行了分析研究。结果表明,该模拟试验方法简单易行,微裂缝与微间隙模拟的过程和微观形态与实际工况接近,试验数据稳定可靠。结论认为,该模拟试验方法能够较好地应用于固井水泥环自修复技术研究和固井水泥浆力学性能分析测试。

Simulation test methods for cementing sheath micro-clearance and micro-crack

So far, there haven’t been unified experimental methods for cementing sheath micro-clearance and micro-crack simulation and self-repairing evaluation. Two kinds of micro-clearance and micro-crack simulation methods are put forward in this paper on the basis of a plenty of exploration experiments in order to do research smoothly in cementing sheath self-repairing technologies. One is that stainless steel pipes are used as casings. The micro-clearances of cementing sheath are simulated by injecting cement slurry after drilling fluid films are painted uniformly on the inner walls of the casings. The other one is that the micro-cracks of cementing sheath are simulated by exerting mechanical extrusion force on the outer wall of steel pipes after the directly injected slurry (no drilling fluid films on the inner wall) is solidified. In this paper, analysis and studies were conducted on the reliability and stability of simulation methods and the micro-forms of simulation samples by means of anti-channeling strength test, experiment error analysis and non-destructive CT scan. Experimental results show that the proposed simulation experimental methods are simple and practical, the simulation process and micro-forms of micro-clearances and micro-cracks are close to the actual working conditions, and the results are stable and reliable. It is concluded that the simulation experimental methods can be better applied to the self-repairing technology research of cementing sheath and the mechanical properties test of cementing slurry.