基于井壁稳定及储层保护的钻井液技术

Drilling fluid technology based on well stability and reservoir protection

陈彬 张伟国 姚磊 严德

CHEN Bin ZHANG Weiguo YAO Lei YAN De

中海石油(中国)有限公司深圳分公司 中海油田服务股份有限公司油田化学事业部 中海油能源发展股份有限公司工程技术分公司

CNOOC China Limited Shenzhen Company, Shenzhen 518054, Guangdong, China Oilfield Chemistry Division, China Oilfield Services Limited, Shenzhen 518000, Guangdong, China CNOOC EnerTech-Drilling & Production Co., Shenzhen 518054, Guangdong, China

南海东部惠州区域上部古近系地层煤层易掉块，硬脆性泥页岩水化膨胀后存在井壁垮塌风险，而下部前古近系火成岩地层温度高、岩石致密、孔渗低，这些地层特点要求钻井液体系具有良好的抑制性能、封堵性能、抗高温性能和储层保护性能，而常规钻井液体系无法同时满足要求。结合邻井资料、地层岩性特点及地质要求，在上部古近系地层使用强封堵聚合物钻井液体系，该体系具有良好的泥页岩抑制性能，且在复合堵漏剂加量仅4%时就具有良好封堵性能；下部前古近系地层使用抗高温无固相钻井液体系，该体系可满足井底150 ℃高温要求，且岩心渗透率恢复率达85%，储层保护性能好。现场应用表明，在上、下地层分别使用两种钻井液体系，解决了古近系煤层掉块、硬脆性泥页岩垮塌问题，满足了前古近系地层高温和储层保护要求，不仅确保了井下作业安全，也为测试作业顺利进行提供了保障，该研究为同类地层钻井钻井液体系优选提供了借鉴。

In Huizhou area of eastern South China Sea, the Paleogene coal bed in the upper part undergoes sloughing easily and there are risks of well collapse after the hydration swelling of hard brittle shale, while the Pre-Paleogene volcanic rock in the lower part is characterized by high temperature, tightness, low porosity and low permeability. These stratigraphic characteristics require drilling fluid system to have good capacities of inhibition, sealing, temperature resistance and reservoir protection, but conventional drilling fluid systems cannot meet all these requirements simultaneously. Based on neighboring well data, lithological characteristics and geological requirements, the strong-sealing polymer drilling fluid system is applied in the Paleogene, which has strong shale inhibition capacity and presents good sealing capacity when the dosage of combined sealing agent is only 4%. The high-temperature solid free drilling fluid system is used in the Pre-Paleogene, which can meet the temperature requirement of 150 ℃ at the bottom hole. In addition, the recovery rate of core permeability is up to 85%, indicating its reservoir protection capacity is good. The field application indicates that applying two different drilling fluid systems in the upper and lower parts respectively solves the problems of coal bed sloughing and hard brittle shale collapse in the Paleogene and satisfies the requirements of high temperature and reservoir protection in the Pre-Paleogene, so as to ensure the safe downhole operation while guaranteeing the smooth testing operation. The research results provide the reference for the selection of drilling fluid systems in the similar strata.

10.13639/j.odpt.2021.02.008