甲酸盐钻井液技术的应用

青海花土沟油田地层压力低。泥页岩地层造浆能力强。钻井过程中易发生地层漏失、井眼缩径、起下钻阻卡和油气层损害严重等问题。该油田采用无固相低密度的甲酸盐钻井液．并配合相应的维护处理工艺技术。该体系主要由碱金属(钾、钠和铯)的甲酸盐、聚合物增粘剂和降滤失剂等组成。其中碱金属的甲酸盐为钻井液提供了适当的密度和强抑制性。在不加任何固相加重剂的情况下，通过改变碱金属甲酸盐的类型和加量，可使甲酸盐钻井液密度达到1．0～2．3g／cm3。现场应用表明．甲酸盐钻井液具有摩阻压耗小，热稳定性好，水力特性优良，页岩抑制性强，污染容限大的特点．减少了井下复杂情况，提高了机械钻速，有效地保护了油气层．提高了原油产量。

Application of formate base drilling fluid technology

Low formation pressure and strong mud making in mud shale stratum exist in Huatugou oilfield of Qinghai, and such problems as circulation loss, hole shringage, blockage during tripping and severe formation damage are frequently encountered. Thus, free solid low density formate base drilling fluid system matches with homologous maintenance technique was applied in the field. The system is mainly composed of formates of Kalium, polymer viscosifying agent and filtrate reducer. Among them, the formates ensure the appropriate density and inhibition of drilling fluid, i. e. , without any solid weighting agent, only changing formate with its type and dosage, the drilling fluid density can reach 1. 0-2. 3 g/cm3. The site using shows that formate base drilling fluid has such properties as low friction factor, good thermal stability, excellent hydraulic performance, better shale inhibition, high contamination resistance. With the use of the system, complex accidents downhole have been reduced, ROP has been increased, formation has been effectively protected and crude oil output has been enhanced in the field.