Drilling Fluid Technology for Shale Oil Exploration and Development in Daqing Oilfield

Abstract

In this paper the geological characteristics, operation difficulties and mechanisms of borehole wall collapse of the Gulong block in Daqing Oilfield are summarized and analyzed in an effort to solve the borehole wall instability problem encountered in shale oil horizontal drilling in the Qijia-Gulong block. Different measures have been presented to solve different problems encountered for the use of oil base muds, such as borehole wall stabilization, mud rheology control and hole cleaning. Key plugging agents such as SFD-1, non-fluorescent anti-collapse agent BY and Soltex were selected for use in the oil base (water-in-oil) drilling fluid that was used in the past and was now optimized. Laboratory evaluation tests showed that the optimized oil base mud has HTHP filter loss of less than 3 mL and is resistant to the contamination from 30% drilled cuttings. Filed application of this mud on the well **2HC in the Gulong block was successful and no downhole troubles have ever happened during drilling. The optimized oil base drilling fluid can be used to solve borehole wall collapse problem encountered in long horizontal drilling, and will have broader prospects of application in shale oil exploration and development in Daqing Oilfield.