反渗透钻井液在东海海域H6-1井的应用

Application of Reverse Osmosis Drilling Fluid in H6-1 Well in the East China Sea

东海盆地位于中国东部海域,其中大量的低孔低渗油气藏有待规模化开发,东海低孔低渗油气藏岩性致密,渗透率极低,埋藏深,储层水锁伤害严重.花港组和平湖组存在大段泥页岩和薄煤层,钻井过程中极易发生井壁失稳,给钻井安全和储层保护带来严峻挑战.反渗透钻井液技术是在低自由水钻井液基础上依据活度平衡和半透膜理论,通过引入纳微米封堵和键合水技术,使钻井液具有反渗透功能.该体系在东海高温深井H6-1井成功应用,应用井段井壁稳定,平均井径扩大率仅1.93%,起下钻顺利,电测和下套管一次到位;抑制性强,钻屑成型,钻进过程中无托压和蹩泵现象;大幅降低钻井液及滤液侵入,随钻测井电阻率与间隔3天完钻后测井电阻率数据相比基本不变;体系具有低活度、低张力特征,有效地保护了低孔低渗油气藏,储层测井表皮系数为负值.反渗透钻井液体系的成功应用满足了东海油气田安全高效开发的需要.

The East China Sea basin is located in the East China Sea, where a large number of low-porosity and low-permeability oil and gas reservoirs with deep-buried and heavy water block formation need to be developed on a large scale. Huagang group and Pinghu group have long section of mud shale and thin coal seam, so borehole wall instability occurred easily in the drilling process,which is a serious challenge for drilling safety and reservoir protection. Reverse osmosis drilling fluid technology is based on low free water drilling fluid and the theory of activity balance and semipermeable membrane. By drawing in a nano-micron sealing and bonding water technology, the drilling fluid has the function of reverse osmosis. The system was successfully applied in the high temperature deep well H6-1 in the East China Sea, and the average hole diameter expansion rate of the applied section was only1.93%. The drilling was smooth, and the electrical test and casing were in target place in one trip. The drilling fluid system has strong inhibition, so the cuttings are in good shape. There is no drag pressure and pump in the drilling process. The invasion of drilling fluid and filtrate is greatly reduced, and the resistivity of logging while drilling is basically unchanged compared with that of logging(after the completion of drilling in 3 days. The system has the characteristics of low activity and low surface tension, which effectively protects low-porosity and low-permeability reservoirs. The successful application of reverse osmosis drilling fluid system meets the needs of safe and efficient developments of oil and gas fields in the East China Sea.