伊朗Y油田F地层防卡技术

摘要

In order to solve the frequent pipe sticking in porous limestone reservoir formation in the Iranian Y Oilfield,based on the properties and pore pressure of F formation,the reasons and types of pipe sticking were analyzed.Different pressure systems are the main reason behind pipe sticking,and there is highly different pressure between the drilling fluid column pressure and formation pore pressure.According to the calculation formula of friction between the drill string and borehole wall,the following technical measures were suggested to prevent sticking:non-invasive drilling fluid system should be applied to seal near wellbore zone,separate drilling fluid column pressure from low pressure formation,and cut the differential pressure transmission; drilling fluid performance be optimized and mud cake quality improved to lower the friction factor between drill string and borehole wall;BHA should be simplified to reduce the contact between it and borehole wall; and separated plugging,well trajectory control and reducing static time of drilling tools in well should be taken as well.Pipe sticking has been eliminated after taking the aforesaid measures in F formation of 13 wells in Iranian Y Oilfield,marking the success in addressing pipe sticking prevention there.%为解决伊朗Y油田在钻进F地层时卡钻事故频发的问题,分析了F地层的地质特征、压力特征和卡钻特征,分析认为,由于F地层裸眼井段存在不同的压力层系,钻井液液柱压力与地层压力之间存在高压差,从而造成了卡钻.根据钻柱与井壁的摩擦力计算公式,提出了防卡技术措施:采用无渗透钻井液封堵近井地层,将钻井液液柱压力与低压地层隔开,阻断压差传递；优化钻井液性能,改善泥饼质量,降低钻柱与井壁的摩阻系数；简化钻具组合,减少钻具组合与井壁的接触面积；分段封堵、控制井眼轨迹和缩短钻具在井内静止时间等配套技术措施.伊朗Y油田的13口井采取该防卡技术措施后,在钻进F地层时没有出现卡钻事故.这表明,采取所提出的防卡技术措施能解决F地层的压差卡钻问题.