强抑制性聚合醇防塌钻井液在大安地区的应用

吉林油田大安地区大208区块青山口组地层为大段硬脆性泥页岩,矿物组分以伊利石为主,存在异常高压,钻井过程中极易发生剥落掉块和井壁坍塌,导致划眼和起钻遇卡等复杂情况.优选出了以强抑制性聚合醇PLG为主要防塌剂并配合使用PA-1防塌降滤失剂的强抑制性聚合醇防塌钻井液体系.在大19-2井和大1-4井的现场试验表明,强抑制性聚合醇与其它处理剂配伍性好,该体系性能稳定,具有良好的抑制性和流变性,现场维护处理简单.该体系的6口推广应用井钻井、完井周期明显缩短,起下钻均很顺利,完钻测井一次成功,未出现起钻遇卡和下钻划眼等复杂情况,有效地解决了该区块井壁稳定问题,提高了钻井速度.

Application of Inhibitive Polyglycol Drilling Fluid in Da'an Area

Qingshankou section of Da-208 block in Da'an area in Jilin oil field is a whole hard and brittle shale which is mainly composed of the illite.Abnormal high pressure exists in the formation.When drilling in the section with silicon-zinc polymer drilling fluid before,borehole sloughing,collapsing,trip difficulties and well log failure occurred frequently.And thus the drilling and completion period were prolonged.In order to solve these challenges effectively,the strongly inhibitive polyglycol anti-sloughing drilling fluid was employed in this area.The field trials of two wells showed that PLG was compatible with other drilling additives and the system was stable and had a favorable inhibition,rheology and also a convenient maintenance.In addition,it was demonstrated from the practices of 6 wells that the strongly inhibitive polyglycol anti-sloughing drilling fluid can overcome the challenge of borehole instability,improve the penetrating rate and can meet the requirements of drilling practices in this area.