MPD Reduces Deepwater Drilling Costs

摘要

Houston-In deepwater and at deep drilling depths offshore, one of the primary problems faced during circulation is excessive equivalent circulating densities (ECD). This problem can become particularly acute in extended-reach wells, especially where the margins between pore and fracture pressures are narrow, and in high-temperature/high-pressure wells, where it is difficult to accurately predict ECD based on assumed mud properties. Excessive annular frictional pressure (AFP) causes a variety of problems-ranging from well bore instability, lost circulation and stuck pipe-and limits the depths to which drilling can be carried out without approaching the formation fracture strengths. Several initiatives are underway to manage this problem. One new method manages pressures during drilling using a subsea pressure monitoring and control device located at the mudline. Returned mud is directed through a subsea control device capable of applying backpressure to the well. Bottom-hole pressure (BHP) is automatically managed and controlled during drilling and circulation using field-proven devices, which allows lighter-weight drilling fluids to be used while preserving desired safety margins.