顺北油田断溶体储集层特征及损害预防

顺北油田储集层埋藏深、裂缝发育、非均质性强.为保证钻井安全,通常采用正压差钻井,但较高密度钻井液对储集层的损害较大.根据岩性和储集空间特征,以及表面润湿性、敏感性、岩石力学特征和储集层段钻井液体系分析,钻井液对储集层的损害主要体现在大量低酸溶率固相侵入并堵塞缝隙、较大毛细管力造成气层水相圈闭及水锁、钻井液耐温性能差造成...

Characteristics and Damage Prevention of Fault-Karst Reservoirs in Shunbei Oilfield

The reservoirs in Shunbei oilfield are characterized by deep burial depth, developed fractures and strong heterogeneity. In order to ensure the safety of drilling, drilling operation at positive pressure difference is usually followed, however, the high-density drilling fluid used may damage the reservoir. After analyzing the lithology, reservoir space, surface wettability, sensitivity, rock mechanical characteristics and the drilling fluid system used in the reservoir interval, it’s found that the damage of the drilling fluid to the reservoir is mainly reflected in such aspects as a large amount of solid phase with low acid solubility invading the reservoir and blocking the fractures, large capillary force causing aqueous phase trapping and water lock in the gas layer, and the drilling fluid with poor temperature resistance causing settlement and excessively high positive pressure difference. In view of the tight matrix and strong heterogeneity of the reservoir in Shunbei Block 1, preventive measures to reduce reservoir damage are proposed, namely “physical plugging-filtrate surfactant control, and hydration inhibition-mechanical approximate balance”, to reduce fluid loss, decrease solid-phase invasion and depth, improve the plugging performance while drilling, and protect the reservoir.