岗钾1井高压卤水层井控技术

Well Control of High Pressure Brine in Well Gangjia 1

岗钾1井是一口地质勘探井,施工时提前钻遇了高压卤水层并发生溢流。关井后先后采用了自环空注加重钻井液的"平推法"和自钻具水眼注加重钻井液的"正注法"平衡地层压力,但由于过饱和卤水在上返过程中结晶速度较快以至于形成环空堵塞,给建立循环带来了很大的困难,在试图建立循环过程中,发现裸眼井段存在易漏失的薄弱层,较难建立液柱平衡压力。针对这些问题,采用精确监测压井过程中的压力变化、合理使用压井液密度、合理调节泵注排量等手段,并以正注、反注相结合的技术措施,最终疏通环空建立了循环,顺利完成了压井作业。

Gangjia 1 is a geological exploration well.It encountered unexpected high pressure brine and followed with overflow during the drilling process.In order to keep the balance of pressure between the formation and the hole,the weighted drilling fluids were pumped in annular space(plunger method) and then the drill string(injection method) after the well was shut in.However,due to the high rate of crystallization for the supersaturated brine in the upward process,well annular space was plugged which was difficult to perform brine circle.In addition,it was hard to balance hydrostatic fluid column pressure in the circulating process due to the existence of fluid leakage in some weak points of the formation.Nevertheless,the hole was finally dredged and the circle was founded by various technical approaches,such as intensive detecting of the pressure change,proper use of load fluid density,rational displacement of pump,composing of forward and inverted injection.Moreover,the well was safely killed and the sub-drill strings were successfully tripped out.