大安地区井壁稳定机理与硅醇成膜防塌钻井液技术

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,矿物组分以伊利石和伊/蒙间层矿物为主,钻井过程中极易产生剥落掉块和井壁坍塌,导致划眼和起钻遇卡等复杂情况.以往在该区块施工主要采用硅铵聚合物钻井液,钻至青山口组掉块严重,完钻起钻遇卡,下钻遇阻划眼,测井一次成功率很低,延误了钻井、完井周期,造成了一定的经济损失.为了有效解决这一困扰钻井生产的技术难题,首先针对该地层岩样进行了井壁失稳的机理研究,确定了相应的稳定井壁的钻井液防塌技术对策,并在室内实验基础上选用了强抑制性硅醇成膜防塌钻井液体系.现场试验表明,强抑制性硅醇成膜防塌剂与其他处理剂配伍性好,钻井液性能稳定,具有良好的抑制性和流变性,现场维护处理简单.该体系的推广应用,有效解决了该区块井壁稳定问题,提高了钻井速度,能够满足该地区的钻井施工.

Wellbore stability mechanism and silicate-polyol membrane anti-sloughing drilling fluid technology in Da'an area

Qingshankou Section of Block Da 208 in Da'an area in Jilin Oilfield is a long section with hard and fragile shale which mainly consists of illite and illite/smectite mixed layers.When drilling operation was implemented in the section with silicate-ammonium polymer drilling fluid in the past,the holebore sloughing and collapsing often occurred.Trips were frequently blocked and the success percentage of well completing logging was very low.Hence,the drilling and completing periods were lengthened.In order to solve this problem effectively,firstly,we carried on the study on the mechanism of wellbore instability with core samples.Secondly,we defined the strategy of wellbore stability and lastly decided on the strongly inhibitive silicate-polyol membrane anti-sloughing drilling fluid in this area based on situ studies.The field tests in 2 wells showed that PLG-3 was compatible with other drilling additives,the property of the drilling fluid was stable with the strong inhibition and the rheology was convenient to maintain.In addition,the application and dissemination of the system in 6 wells showed that the strongly inhibitive silicate-polyol membrane anti-sloughing drilling fluid solved the technical problem of wellbore stability and accelerated the penetrating rate.