固井前钻井液性能调整及前置液紊流低返速顶替固井技术

Cementing technologies to adjust drilling fluid properties before cementing and displace mud by turbulent prepad fluid at low return-velocity.

结合油田现场施工作业 ,为提高顶替效率 ,提出了固井前钻井液性能地面调整及前置液紊流低返速顶替固井技术。在保证钻井液形成薄而韧的致密泥饼的基础上 ,固井前对其流变性能进行调整 ,降低钻井液动切力、塑性粘度、静切力 ,可降低流动摩阻压力 ,防止顶替过程中泵压过高压漏薄弱地层 ,并能有效除去大块钻屑 ,预防电测遇阻。在顶替钻井液时 ,采用前置液紊流冲洗、水泥浆低返速顶替固井技术 ,可以保证流动剖面层层推进 ,即控制钻井液的动塑比<前置液的动塑比 <水泥浆的动塑比 ,前置液的环空压耗 <领浆的环空压耗 <尾浆的环空压耗 ,前置液的雷诺数 >领浆的雷诺数 >尾浆的雷诺数。两项措施结合可有效提高冲洗效率与顶替效率 ,改善第二界面胶结质量 。

In an effort to increase displacement efficiency, cementing technologies to adjust drilling fluid properties before cementing and displace mud by turbulent prepad fluid at low return-velocity was proposed, referring to oilfield field operations. The pre-cementing drilling fluid property adjustment means,on the premise that the drilling fluid can construct a thin, plastic and compacted mud-cake, to deduce the fluid's yield value, plastic viscosity, static shear force, resulting flowage friction drag to be lowered, also leakage of thin layer by overhigh pumping pressure during displacing operation. In addition, massive drilling cuttings will be removed effectively, avoiding small drill pipe placing when electronic logging instrument sticking occur. The turbulent pad fluid cleaning together with low return-velocity displacing technology is to Control the ratios of dynamic shear force to plastic viscosity following order as the drilling fluid<the pad fluid<the cement slurry, the annular pressure losses follow the pad fluid<the collar slurry<the tail slurry, and the Renault Numbers follow the pad fluid>e collar slurry>the tail slurry, respectively.Combining above two means together in cementing operation, cleaning efficiency and displacing efficiency will be both increased, consolidation of the second surface will be improved, and the cementing quality improved also.