High Density and High Performance Drilling Fluid System Research and Application at Pakistan North Region ADHI Block

The mid-upper Early Miocene Murree formation in the ADHI block, northern Pakistan, is a long red mudstone located in the Φ311.15 mm interval with a length of 1400-1600 m, which is a major difficulty and extremely challenging drilling operation in the block. The red mudstone section has the characteristics of strong dispersion and high slurry production, and the rheological property of drilling fluid is often out of control. Easy to expand and shrink, bit balling, return a large ball of cuttings, blocking the horn; The formation pressure coefficient is high, the density is as high as 1.80-2.00 g/cm³, and the accidents such as differential pressure sticking and broken drilling tools often occur. Formation water, high pressure and low permeability, 1-3 m³/h; The high density further increases the difficulty of controlling rheology and poor solid content of drilling fluid. In order to solve the above Drilling problems in the AHDI block, show Chuanqing's image as a pioneer in complex oil and gas drilling in the open oil and gas service market overseas, and establish the brand of "CCDC Drilling Fluid", the author conducted analysis and research on the mineral components and hydration characteristics of mudstone in the Murree formation. A high-density high-performance water-based drilling fluid system with a density of 2.20 g/cm³, yield point less than 20 Pa, temperature resistance of 100℃ and resistance to 5% mudstone pollution suitable for ADHI block in northern Pakistan was developed based on "efficient mudstone inhibitor, clay accretion inhibitor and ROP Enhancer, nano-microne plugging agent and application technology of macromolecule encapsulation inhibitor under high density conditions". Successfully applied 4 Wells in Pakistan.