WELLBORE HYDRAULIC COMPLIANCE

摘要

A method for determining hydraulic compliance of a wellbore during a managed pressure drilling procedure. Measurements are made of the pressure of a drilling fluid being circulated in the wellbore during the procedure at the top of a drilling annulus, the flow rate qin of the drilling fluid into the wellbore and the flow rate qout of the fluid out of the wellbore. These three measurements are used to determine the difference of the flow rates and a discrete time derivative (Pt−Pt-Δt)/Δt of the pressure, where t is time and Δt is a time interval. The differences in flow rates and the time derivatives are then processed by applying a low pass filter to determine the hydraulic compliance of the wellbore.

主权项

1. A method of determining a hydraulic compliance of a wellbore during an operation to pump fluid into a flow path which extends downhole through tubing located in the wellbore and then returns in an opposite direction through an annulus surrounding the tubing to a topside end of the annulus, the method comprising:
receiving measurements of the pressure P of the fluid at the topside end of the annulus; receiving measurements of a flow rate qin of the fluid into at least a portion of the flow path; receiving measurements of a flow rate qout of the fluid out of said portion of the flow path; determining a difference of the flow rates (qin−qout), wherein the difference of the flow rates comprises difference between the flow rate qin and the flow rate qout; determining a discrete time derivative of the pressure, wherein the discrete time derivative comprises (Pt−Pt-Δt)/Δt where t is time and Δt is a time interval; processing the difference of the flow rates and the discrete time derivative of the pressure by applying a low pass filter to at least one of the difference of the flow rates and the discrete time derivative of the pressure; and determining a hydraulic compliance of the wellbore for said portion of the flow path as a gradient of a straight line fitted to values of the processed difference of the flow rates plotted against values of the processed discrete time derivative of the pressure.