High Performance Water Base Drilling Fluid for Shale Gas Drilling

A high performance water base drilling fluid is in urgent need to replace the oil base muds currently used in shale gas drilling in both the directional section and the horizontal section. This paper discusses the field application and laboratory study of two high performance water base drilling fluids. One of the high performance drilling fluids, GOF, has been used in the horizontal section of the well Changning H9-4, the directional and horizontal sections of the well Changning H9-3, and the well Changning H9-5. Another high performance drilling fluid is a highly inhibitive water base fluid of high lubricity, and has been used in the horizontal well YS108H4 in the block Zhaotong. This fluid utilizes organic and inorganic salts as the shale inhibitors and lubricant and diesel oil to render the fluid lubricity. In filed application, the ROP of the directional section was increased by 50%-75%, and that of horizontal section increased by 75%-100%. Advantages and disadvantages of the two fluids are discussed in the paper, based on laboratory experimental data and field application information. Ideas to improve the performance of the fluids are presented for the preparation of better high performance water base drilling fluids.