Calculating Downhole Card in Deviated Wellbore Using Parameterized Segment Calculations
First Claim
1. A method of diagnosing a pump apparatus having a downhole pump disposed in tubing of a deviated wellbore, the downhole pump reciprocated in the tubing by a rod string operatively moved by an actuator at surface of the deviated wellbore, the method comprising:
- obtaining surface data indicative of surface load and surface position of the rod string at the surface;
calculating downhole data from the surface data by solving a wave equation having viscous damping and Coulomb friction factors;
accounting for a mechanical friction factor between the rod string and the tubing in the calculation of the downhole data by;
parameterizing segments of the deviated wellbore;
mapping the rod string to the parameterized segments;
computing forces experienced by the mapped rod string during operation relative to the parameterized segments using force equations characterized for pulling out and running in the mapped rod string in the parameterized segments, andusing the computed forces in the solution of the wave equation to calculate the downhole data; and
generating information from the downhole data representative of downhole load relative to downhole position of the downhole pump.
8 Assignments
0 Petitions
Accused Products
Abstract
In a deviated wellbore, a pump system computes downhole data from surface data by solving a wave equation that takes both viscous damping and Coulomb friction into consideration. Mechanical friction between the rods, couplings, and tubing is considered in the calculation of downhole data in the deviated wellbore by modelling the wellbore'"'"'s trajectory, parameterizing various deviated segments (build-ups, slants, drop-offs, etc.) in the trajectory, mapping the rod string to the segments, and incrementally evaluating position of the mapped string over time in order to compute drag forces and side loads experienced by the rod string during operation. These computed drag forces and side loads are then used in the solution of the wave equation to solve the surface load and position data and provide more accurate downhole position and load data.
-
Citations
21 Claims
-
1. A method of diagnosing a pump apparatus having a downhole pump disposed in tubing of a deviated wellbore, the downhole pump reciprocated in the tubing by a rod string operatively moved by an actuator at surface of the deviated wellbore, the method comprising:
-
obtaining surface data indicative of surface load and surface position of the rod string at the surface; calculating downhole data from the surface data by solving a wave equation having viscous damping and Coulomb friction factors; accounting for a mechanical friction factor between the rod string and the tubing in the calculation of the downhole data by; parameterizing segments of the deviated wellbore; mapping the rod string to the parameterized segments; computing forces experienced by the mapped rod string during operation relative to the parameterized segments using force equations characterized for pulling out and running in the mapped rod string in the parameterized segments, and using the computed forces in the solution of the wave equation to calculate the downhole data; and generating information from the downhole data representative of downhole load relative to downhole position of the downhole pump. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
-
-
20. A method of diagnosing a pump apparatus having a downhole pump disposed in a deviated wellbore, the downhole pump reciprocated in the deviated wellbore by a rod string operatively moved by an actuator at surface of the deviated wellbore, the method comprising:
-
obtaining a trajectory of the deviated wellbore; parameterizing a plurality of segments in the trajectory; mapping nodes of the rod string in time increments to the parameterized segments of the trajectory; obtaining surface measurements indicative of surface load and surface position of the rod string at the surface; computing, from the surface measurements, forces of each of the nodes of the rod string in the time increments mapped to the parameterized segments of the trajectory using force equations characterized for pulling out and running in the nodes in the parameterized segments; computing downhole data of load and position by solving a wave equation using the surface measurements and using information from the computed drag forces and the side loads as boundary conditions; and generating information representative of downhole load relative to downhole position of the downhole pump based on the solution of the wave equation.
-
-
21. A controller for a pump apparatus having a surface actuator and having a downhole pump, the downhole pump disposed in a deviated wellbore and reciprocated by a rod string disposed in the deviated wellbore, the controller comprising:
-
one or more interfaces obtaining surface measurements indicative of surface load and surface position of the rod string at the surface; memory in communication with the one or more interfaces, the memory storing a trajectory of the wellbore having a plurality of parametrized segments and storing a mapping of the rod string to the parameterized segments; and a processing unit in communication with the one or more interfaces and the memory and configured to; calculate downhole data from the surface data by solving a wave equation having viscous damping and Coulomb friction factors; compute, with force equations characterized for pulling out and running in the mapped rod string in the parameterized segments, forces experienced by the mapped rod string during operation, use the computed drag forces and the side loads in the solution of the wave equation to calculate the downhole data to account for a mechanical friction factor between the rod string and the tubing in the calculation of the downhole data; and generate information from the downhole data representative of downhole load relative to downhole position of the downhole pump.
-
Specification