Anti-Gas Channeling Cementing Technology for Ultra-Deep High Temperature and High Pressure Gas Wells

Abstract

Many challenges exist in ultra-deep high-temperature and high-pressure gas well cementing, such as, high-temperature, active gas layer, narrow density window, and seal integrity failure of cement sheath, which brings huge difficulties in anti-gas channeling cementing. By selecting the nano-liquid silicon and latex anti-gas channeling agents, and synergistically enhancing the anti-gas channeling performance of cement slurry, the mechanical properties of cement set is improved; by optimizing the compounding and dosage of silicon powder with different particle sizes, the high-temperature stability of cement set is enhanced. Via the selection of inorganic fiber cracking-prevention and plugging system, the crack propagation is inhibited, and the leakage resistance of cement slurry and the impact resistance of cement set are improved. Hence, a high-temperature resistant latex anti-gas channeling cement slurry system was developed. The cement slurry system has the following properties: API water loss of <50 mL at 180 °C, SPN value of <1, cement set compressive strength of 39.3 MPa under 200 °C×21 MPa×60 d, Young's modulus of 6.9 GPa, gas layer permeability of 0.004×10-3 μm2, and its comprehensive mechanical properties are better than that on the 30th day. The cement sheath seal integrity evaluation shows that the 26.7 mm sheath can achieve an effective seal effect under the cyclic loading process (peak pressure is 90 MPa). Combined with the staged gas layer stability prediction, the pressure management cementing technology under unsteady conditions was proposed, which solves the problems of gas channeling and leakage prevention in ultra-deep high-temperature and high-pressure reservoirs with enriched fracture-cavity. The anti-gas channeling cementing technology has been used in the Shunnan and Shunbei plays of Sinopec Northwest Oilfield Company, and it can provide references for the cementing of similar gas wells.