胡109井保护油气层钻井液技术

Drilling fluid technology tor formation protection in well Hu-109

胡109井是一口岩性油气藏重点评价井,油气层中普遍存在着粘土矿物,尤其存在着水敏性粘土矿物、可运移的微粒及酸敏性矿物,物性差,易与不配伍的外来流体发生化学反应,导致储层损害。胡109井实施的保护油气层钻井液技术包括:优选与储层矿物及地层水配伍性好的处理剂配制钻井液,并在钻井液中加入与岩石孔喉配伍的固相颗粒,包括架桥粒子、填充粒子和可变形粒子,上部井段(1500～3000 m)使用聚合物正电胶钻井液,下部井段(3000～4500m)使用聚磺饱和盐水钻井液;在钻井过程中重视固控设备的使用,优化钻井液中有用固相的级配关系;在近平衡钻井作业中保持适当的压差;使钻井液在近井壁范围(2～3 cm)内迅速形成致密的内、外泥饼;在工程上操作平稳,以免破坏滤饼和冲击压差增大使滤失量增加。试油结果表明,初期原油日产量为33.58 m^3,天然气日产量为12457 m^3,是近年来东濮凹陷产量最高的一口探井。

Well Hu-109 is an important lithologic reservoir evaluation well, and the clay minerals exist in the reservoir. The water sensitive clay minerals, migrating fine particles and acid sensitive minerals has poor physical property, and are likely to react with the incompatible foreign fluids, thus cause formation damage. Formation protection drilling fluid technologies are carried out in well Hu-109, e. g. , selection of proper mud additives that compatible to formation minerals and foreign fluids, and adding into the drilling fluid of solids that is compatible to formation pore throats, including bridging particles, filling particles and size-variable particles. In the upper interval (1500--3000 m), MMH drilling fluid is used; and polysulfonate saturated salt-water drilling fluid is used in the lower interval (3000 -4500 m). Solid control equipment is used during drilling, to optimize the grades matching of useful solids. In near-balanced drilling, proper pressure differential is kept to aid the forming of inner and outer mud cake near the bore wall area (2-3 cm). Carefully operation of drilling tools is carried out, to avoid the damage to mud cake and rise of impacting differential, which can lead to high filtration. Production tests show that the initial crude oil and natural gas production rate is 33. 58 m3 and 12457 m3 per day respectively, which is the highest production exploration well in Dongpu Sag in recent years.