The high Aclinic-vertical ratios horizontal well drilling and completion technology of shale oil in Changqing oilfield

The loess plateau shale oil demonstration zone has a landform, the ravines, fragile ecological environment, many water resource reserves, basic farmland reserves in the Longdong Gansu province of China. Under the premise of protecting the surface ecological environment, to maximize the use of oil and gas reserves poses a challenge to the drilling and completion of extra long horizontal Wells with the high aclinic-vertical ratios. The construction experience of 4,000 meters horizontal Wells completed in the previous stage was summarized and analyzed, the possible problems were demonstrated and studied. Through the technical Researches of optimizing the supporting rig and key drilling tools, optimizing the well structure and profile design, fine trajectory controllability, innovative water-based drilling fluid system, rapid plugging technology, optimizing floating casing technology, reducing friction and torque in construction, etc. Two extra long horizontal Wells with the aclinic-vertical ratios of more than 2.35 were completed successfully, the construction process was safe and efficient, with minimal incremental drag and torque in the horizontal section. There has achieved good field application effect, formed the key drilling and completion technology of extra long horizontal Well with high aclinic-vertical ratios in the 7th member of Yanchang Formation of shale oil.