玉北地区钻井液技术

针对玉北地区古近系膏岩层易蠕变缩径、二叠系火成岩地层易垮塌掉块、奥陶系灰岩地层易漏,导致的钻井周期长、机械钻速低、复杂情况多等问题,优选了适合各开次的钻井液体系。一开选用膨润土聚合物体系,利用其高膨润土含量解决地表流沙层的井壁稳定与井眼清洁问题;二开选用KCl聚磺钻井液,通过强化钻井液的抑制封堵能力与抗污染能力解决了因泥岩段水化膨胀、砂岩段形成虚泥饼造成的阻卡问题,实现了井壁稳定;三开选用KCl聚磺防塌钻井液,解决了高密度钻井液的抗污染问题,实现了深部地层的快速钻进;四开选用低固相聚磺钻井液,大幅度提高了深部地层的钻进速度。

Drilling Fluid Technology of Yubei Area

Yubei area lies on the southwest of Taklimakan desert in Tarim basin. Because of the creeping and hole shrinkage gypsum bed in Gujin,and the easily collapsing and caving-in igneous rocks in Permian,as well as the leakiness Ordovician limestone,the drilling speed is low and therefore the drilling cycle is quite long. In order to solve these problems,this article optimizes the drilling fluid system suitable for different phases based on lots of experiments and field applications. For the first section,the bentonite polymer system is applied to ensure the wellbore stability of surface float land and to clean the wellbore. For the second section,KCl polysulfonate drilling fluid is used to solve the stuck problem caused by the hydrate expansion in the mudstone section and the pseudo cake in sandstone section in order to ensure the stability of the wellbore. For the third section,the KCl polysulfonate anti-sloughing drilling fluid is selected to solve the antipollution problem of high density drilling fluid so as to realize the fast drilling in deep formation. For the forth section,the low solid polysulfonate drilling fluid is applied to speed up the drilling velocity in deep formation.