欠平衡技术 Underbalanced Operations Technology.ppt

Drilling with the hydrostatic head of the drilling fluid intentionally designed to be lower than the pressure of the formations being drilled. The hydrostatic head of the fluid may be naturally less than the formation pressure or it can be induced. The induced state may be created by adding natural gas, nitrogen or air to the liquid phase of the drilling fluid. Whether the underbalanced status is induced or natural, the result may be an influx of formation fluids which must be circulated from the well and controlled from the surface. Underbalanced Drilling Preservoir Pbottomhole = Phydrostatic + Pfriction + pchoke Fluids and combinations available for UBD Fluid Selection Matrix Fluid System Base Fluid Gas Gas Injection Method Gas Mist Foam Gasified Fluids Single phase Fluids Brines Weighted Fluids Drill string Injection Annular Injection Combined string/annular injection Air Nitrogen Natural Gas Exhaust Gas Water Sea water Fresh water Formation Water Oil Diesel Oil Active Crude Vegetable Oils distillates Mud waterbased mud oi l based mud Brines KCL Brines Chloride Brines Bromite Brines Zinc Brines Formate Brines Increasing Density UBD Drilling Fluids and Weights Average Gradients in ppg of several mud weights UBS PROJECT MANAGEMENT Road Map The importance of good planning Safety during tripping operations The tripping method in an underbalanced drilled well is crucial. Avoiding pipe light and snubbing can reduce the risk level significantly. RCD’s are a key enabling technology for UBD Williams models are most commonly used Passive annular seals (stretch-fit stripper rubbers) Require no external to the tool source of energy to function 420 on U.S. land rigs today (1600 Rig Count) UBD MPD AD Hydraulic Flow Models for UBD MPD Manpower requirements for UBD Flow Control Matrix for Williams Model 7100 RCD Semi-Automatic Chokes are used for UBD and MPD Swaco SuperChoke, 10,000 20,000 psi ROTATING PLATES DIRECTION OF FLOW Dedicated Choke Manifolds for UBD