Study and Application of “All-in-One Bag” Multi-Function Drilling Fluids

A new environmentally friendly multi-function drilling fluid additive PF-MFA was synthesized through dispersion polymerization. PF-MFA can be used as viscosifier, gelling agent, shale encapsulator, shale inhibitor and filter loss reducer. A new “all-in-one bag” drilling fluid was formulated with PF-MFA as the unique core additive, seawater and weighting agent as the auxiliary additives. This new drilling fluid has simple composition and high performance. A drilling fluid treated with 1% PF-MFA, after hot rolling at 80 ℃, still had high viscosity, gel strengths and strong inhibitive capacity, the API filter loss was controlled at less than 6.5 mL. The salt, clay and calcium(CaCl₂) resistance of this drilling fluid were 20%, 15% and 2%, respectively. This drilling fluid is also biodegradable and is thus environmentally friendly. This “all-in-one bag” drilling fluid has been successfully used in the well V40 in the Block PL19-3 in Penglai, Bohai. Field operation showed that less amount of drilling fluid additives was required for the “all-in-one bag” drilling fluid to achieve the same goal. Stable and easy to maintain properties as well as simple composition of the “all-in-one bag” drilling fluid can satisfy the needs of drilling production wells and adjustment wells penetrating relatively easy-going formations.