油井水泥石脆性降低的途径及其作用机理

Reduction in friability of well cement stone and its function mechanism

关键词:  固井  水泥环  油井水泥  韧性  胶乳  纤维  橡胶粉  弹性模量

Key words:  cementing  cement sheath  well cement  toughness  latex  fiber  rubber powder  elastic module

摘要:

针对国内油田薄油层井、小间隙井和侧钻井固井后射孔及后续增产措施造成的水泥环脆裂(即二次窜流)问 题,为了降低水泥石的脆性,正确评价不同材料对水泥石韧性或弹性的影响,对掺有胶乳、橡胶粉和PVA纤维水泥 石的抗折强度、抗压强度、抗冲击功和弹性模量等力学性能进行了研究,并对3种材料的作用机理进行了剖析。研 究结果表明，与净浆水泥石相比,掺有胶乳和橡胶粉水泥石的弹性模量分别降低了 69% ~76%和-60%，掺有 PVA纤维水泥石的抗冲击功和抗折强度分别提高了9% ~89%和16% ~37%。胶乳、橡胶粉与水泥水化产物的有 效铰接和桥联作用显著提高了水泥石的弹性,PVA纤维的有效阻裂作用显著提高了水泥石的韧性。

Abstract:

Aiming to the problem of the brittle fracture of cement sheath caused by perforation and other production enhancing measures after well cementing of thin oil reservoir wells, latex, rubber powders and PVA fibers were studied to reduce cement stone friability and distinguish the toughness and elasticity of cement stone accurately. The mechanical properties of well cement stone mixed latex, rubber powders and PVA fibers were measured, and the function mechanism of above mentioned materials was analyzed. The results show that compared with net cement stone, the elastic modules of well cement stone with latex and rubber powders are decreased by 69% ~76% and 49% ~60% respectively. The flexural strength, the impact work of cement stone with PVA fibers are increased by 9% ~ 89% and 16% ~37% respectively- Articulation and bridging of latex and rubber powders can improve the elasticity of well cement stone remarkably. Crack resistance behavior of PVA fibers can improve the toughness of cement stone markedly.