Drilling and Completion Techniques for Horizontal Wells in the Deep Buried Hills of the Nanpu No.2 Structure

In order to solve the technical problems such as lost circulation,overflow,low ROP and long drilling periods in the drilling of horizontal wells in the deep buried hills of the Nanpu No.2 Structure,drilling and completion techniques for horizontal wells in deep buried hills were studied.According to geomechanical and geological characteristics of strata,the pressure sensitivity of buried-hill reservoirs,and the problems of lost circulation and overflow,the fourth and fifth casing programs were designed for the horizontal wells in deep buried hills.Further,a "three build-up and seven sections" borehole trajectory,i.e.,"vertical-build-up-holding-build-up-holding-build-up-horizontal" was designed for such wells.The deflecting tool with rated temperature of 175℃,MWD monitoring instrument,and high temperature (220℃) oil-in-water drilling fluid system were selected.Application studies on micro-flow precise pressure management for horizontal wells and completion techniques with high-temperature gel valve were performed.Then a set of drilling and completion techniques suitable for horizontal wells in deep buried hills of Nanpu No.2 Structure were formed.Those techniques have been used in the drilling operations of 15 horizontal wells,with well depths achieving 5 600.00 m,and horizontal displacement over 4 000.00 m,in deep buried hills of Nanpu No.2 Structure,in which complexities like lost circulation and overflow were effectively controlled.Using the modified drilling and completion techniques resulted in achieving safe and high efficient development of deep buried-hill reservoirs in the Nanpu No.2 Structure,and the potential for continuing to achieve additional improvements.