莫北油田莫109井区不下技术套管的钻井液技术

Drilling Fluid Technology in Wells With No Intermediate Casings in Mobei Oilfield

莫109井区位于莫北油气田的南部，地层造浆、缩径严重，煤层极易坍塌、漏失。此外，为降低钻井综合成本，该区块采用二开井身结构，二开裸眼段长达3700-3800m。该区块钻井的主要难点是严重缩径引起的提下钻阻卡、划眼、开泵发生憋漏以及西山窑组煤层的垮塌等现象。为实现不下技术套管井的安全钻井，从钻井液技术方面制定出了解决方案，通过采用钾钙基聚磺钻井液，并在维护处理过程中保证该钻井液具有强抑制性、低滤失量、良好的携砂能力和流变性，达到了缩短钻井周期、提高钻井时效、节约钻井成本的目的。建议采用防泥包钻头，同时应在钻井液中加入防泥包处理剂。

Well Mo-109 is located in the south of Mobei oilfield in Xinjiang.Formations penetrated by this well are mud making in nature.Tight hole and coal beds were frequently encountered in this well.The well had two sections,with the second section opened for 3700-3800 m.Tight hole in the well resulted in friction and resistance during tripping,reaming,mud loss when start pumps,and the sloughing of the coal beds.A mud program was engineered to solve these problems.Using the potassium-calcium treated polymer sulfonate mud,no downhole problems related to drilling fluid were encountered.For better performance of this mud,it is suggested that the anti-balling drill bits be used.