中原油田天然气井保护储层钻井液技术

DRILLING FLUID TECHNIQUES OF PROTECTING RESERVOIRS IN THE GAS WELLS IN ZHONGYUAN OIL FIELD

中原油田天然气藏属典型的复杂断块、深层、低孔隙度、低渗透率、凝析气藏 ,勘探开发难度大。特别是东濮凹陷黄河南地区的气井 ,在以往的钻井完井过程中 ,由于没有采取全面系统的油气层保护技术 ,使储集层受到了不同程度的损害。因此 ,出现了在钻井过程中一般能见到良好的油气显示 ,而在进一步测试作业时却达不到理想测试效果的现象。通过对重点天然气区地层粘土矿物的研究 ,分析了钻井过程中造成地层伤害的主要因素 ,有针对性地研究了综合配套工艺技术 ,制定了相应的保护油气层技术规程 ,探索出了适合中原油田天然气井保护储层的钻井液技术 ,主要包括聚合醇钻井液、高钙盐钻井液、油包水乳化钻井液、甲酸盐钻井液、钾盐—聚磺防塌钻井液以及固相化学清洁剂和屏蔽暂堵技术等。通过推广应用这些保护气层钻井液技术 ,在 2 0 0 3年完成天然气钻井12口 ,有效地保护了天然气储层 ,最大程度地保持了储集层的原始物性 ,其中在桥 90、白 71、濮 8- 2、桥 91等一批重点探井发现多层高产油气藏。

The natural gas reservoirs in Zhongyun Oil Field belong in the typical complicated block condensate gas reservoirs with great burial depths, low porosities and low permeabilities so that it is difficult to carry out gas exploration and development. Especially in the gas wells on the south of Yellow River in Dongpu Depression, the reservoirs were damaged in varying degrees in the processes of drilling and completion in the past because of the overall and systematic reservoir protection techniques' being not taken. Therefore the phenomena, that good oil and gas shows could be found in the process of drilling but there were no ideal test results, appeared at last. Through investigating the clay min erals of the strata in key gas-bearing regions and analyzing the main factors causing formation damage in the process of drilling, the integrated and matching techniques were studied with strong purposefulness, the relevant technical rules of protecting reservoirs were drawn up and the drilling fluid techniques of protecting reservoirs in the gas wells in Zhongyuan Oil Field were found out They are polymeric alcohol drilling fluid, high calcium salt drilling fluid, water-in-oil emulsification drilling fluid, formate drilling fluid, potassium salt-poly-sulfonate sloughing-prevention drillling fluid and solid chemical cleaning agent as well as shielding temporary plugging technique, etc. Through popularizing these drilling fluid techniques, the gas reservoirs in twelve gas wells drilled in 2003 were effectively protected, their original petrophysical properties being maintained to the maximum limit, and the multizone high-yield oil/gas reservoirs were found in many key exploration wells, as wells Qiao-90, Bai-71, Pu-8-2 and Qiao-91, etc.