土库曼斯坦南约洛坦气田复杂盐膏层钻井液技术

Drilling fluid technology used in the complicated gypsum beds in the South Yoloten Gas Field,Turkmenistan

土库曼斯坦南约洛坦气田的主力产层位于盐膏层之下,曾因盐膏层地质情况复杂和工程事故频发而一度不能钻达设计井深。该区存在一系列的钻井难题:①随巨厚盐膏层而来的"盐水侵"、"钙镁侵"等导致钻井液受到严重污染;②地层疏松和高压气体所造成的"气侵"使井漏与溢流(井涌)并存;③井下高温、高压环境使钻井液性能变差;④高密度钻井液因其固有的高固相所造成的流变性控制难。为此,中国石油天然气集团公司川庆钻探工程有限公司研发并使用了以体系组成简单且高效、配制有序且逐步放大量为特点,以"护胶为主、增强抑制性"为维护处理技术思路的高密度饱和盐水聚磺钻井液,其组成为:基础材料类(膨润土、烧碱、纯碱、NaCl、KCl等)+聚合物类(PAC、FA367、XY-27、JT888等)+磺化材料类(SMP-2、SMC、SPNH、JNJS-220、SMT、FT-1等)+加重剂(重晶石)+辅助材料类(润滑剂、消泡剂、盐重结晶抑制剂等)。此举,提高了高固相含量钻井液体系的综合性能。该钻井液应用于现场,克服了各种因地质因素所造成的钻井液污染破坏问题,突破了该气田钻井技术"瓶颈",成功解决了该气田盐膏层井段所惯存的蠕动、缩径、垮塌等技术难题,确保了该区12口天然气探井盐膏层钻井任务的安全、顺利完成。

The major payzone of the South Yolotan Gas Field in Turkmenistan underlies the gypsum,usually the drilling target can not be reached due to the complicated geological conditions in the gypsum rocks and the accidents thus frequently occur there.The drilling challenges there include: 1) drilling fluid is seriously contaminated by the salt water,calcium ions,magnesium ions;2) lost circulations and oil kicks occurred due to the gas influx caused by unconsolidated formations and high pressure gas;3) drilling fluid performance becomes worse under high pressure and high temperature;4) the rheology of the high-density fluid is hard to control due to the high solid content inside the fluid.In view of this,the CNPC Chuanqing Drilling Engineering Company has developed a special high-density saturated salt water poly-sulfonate drilling fluid with the simple effective composition,designed in accordance with the principle of 'Protecting Glue Cell while Improving the Inhibiting Property'.The composition includes basic materials(bentonite,NaOH,Na2CO3,NaCl,KCl),polymers(PAC,FA367,XY-27,JT888),sulfonates(SMP-2,SMC,SPNH,JNJS-220,SMT,FT-1),weighting agent(barite),and other supplementary materials(lubrication materials,defoamers,crystallization inhibitors).The field test showed that the comprehensive performance of the high solid phase content drilling fluid system was enhanced.It not only overcame the difficulty of drilling fluid contamination due to many geological factors,but also resolved many technical problems of salt-gypsum beds such as peristaltic stratum,hole shrinkage and hole collapse.During the successful drilling process of salt-gypsum beds,the bottleneck problems have been solved and the drilling fluid techniques for complicated salt-gypsum beds have been successfully accomplished in the twelve gas wells in this gas field.