鄂尔多斯盆地长北气田储层保护技术

为了评价钻井过程中钻井液对鄂尔多斯盆地长北气田储层的伤害程度并评选低伤害完井液，实验中应用先进的AC-FDS-800~10000地层伤害系统，在模拟正常钻井和储层参数条件下成功地完成了3套钻井完井液体系对长北气田储层的伤害程度评价。实验结果表明：逆乳化油钻井液对该储层伤害率高达73.91%，因伤害发生在整个岩心而不易解除；油基钻井液对气层岩心几乎100%伤害，但油基钻井液滤失很小，浸入井壁的深度浅，在完井后储层开展射孔或压裂，则伤害很容易解除；相比之下，无黏土低伤害暂堵钻井完井液体系对气层平均伤害率为11.11%，暂堵性好，完钻后可以采取裸眼完井，井壁上形成的暂堵滤饼通过气层压裂完成解堵，并直接气举投产，很大程度上简化了完井、投产作业，值得推广应用。

Reservoir protection technology in the Changbei gas field, Ordos basin

In order to estimate the reservoir damage made by drilling fluids in Changbei gas field and choose low damage completion fluids, the advanced AC-FDS-800~10000 formation damage system was successfully applied to evaluate the damage made by three drilling &; completion fluid systems under simulated normal drilling conditions and reservoir conditions. The experimental results show that damage ratio of invert oil emulsion drilling fluid to the pay zone is up to 73.91%, and the damage is not easy to remove due to its filtration into the whole core. Oil based drilling fluid caused nearly 100% damage to the core, but not so deep filtration into wellbore due to low filtration of OBM, the damage can be removed by perforating or fracturing reservoirs after completion. While the average damage ratio of a kind of clay free low damage drilling &; completion fluid is only 11.11%, and it has good temporary plugging effects. Open hole completion can be adopted after drilling to TD with the fluid, the temporary plugging cake formed on the well bore can be removed by reservoir pressure. And then the well can be put into production directly by gaslift. The completion and production procedure is thus largely simplified.