Fluid load line calculation and concavity test for downhole pump card

Patent metadata

Field	Value
Publication number	US-9810212-B2
Application number	US-201213663161-A
Country	US
Kind code	B2
Filing date	Oct 29, 2012
Priority date	Oct 28, 2011
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A pump apparatus has a downhole pump disposed in a wellbore and has motor at a surface of the wellbore, and the downhole pump is reciprocated in the wellbore by a rod string operatively moved by the motor. A card indicative of load and position of the downhole pump is generated using surface measurements and a wave equation model having a damping factor or two damping factors. Actual fluid load lines are determined from the downhole card for upstroke and downstroke of the downhole pump, and calculated fluid load lines from the load distribution of the downhole data. The actual fluid load lines are compared to the calculated fluid load lines so that at least one parameter of the pump apparatus can be modified based on the comparison. For example, the damping of the wave equation model can be adjusted so that another downhole card can be generated.

First claim

What is claimed is:

1. A method implemented by a processing device of diagnosing a pump apparatus having a downhole pump disposed in a wellbore and having a motor at a surface of the wellbore, the downhole pump reciprocated in the wellbore by a rod string operatively moved by the motor, the method comprising:
generating downhole pump data having values indicative of downhole load and downhole position of the downhole pump by using surface measurements and a wave equation model having damping;
determining, in a first determination, a first set of actual fluid load lines for actual fluid loads of each of an upstroke and a downstroke of the downhole pump from the values of the downhole pump data, the actual fluid load lines being additional to the values of the downhole pump data;
determining, in a second determination different from the first determination, a second set of calculated fluid load lines for calculated fluid loads of each of the upstroke and the downstroke of the downhole pump from load the values of the downhole pump data, the calculated fluid load lines being additional to the values of the downhole pump data and to the actual fluid load lines;
assessing damping used to generate the downhole pump data by comparing the first set of actual fluid load lines to the second set of calculated fluid load lines; and
modifying at least one parameter of the pump apparatus based on the comparison.

2. The method of claim 1 , comprising initially obtaining the surface measurements indicative of surface load and surface position of the rod string at the surface.

3. The method of claim 2 , wherein obtaining the surface measurements comprises measuring the surface load and the surface position of the rod string at the surface.

4. The method of claim 2 , wherein obtaining the surface measurements comprises obtaining the surface measurement from memory.

5. The method of claim 1 , wherein determining, in the first determination, the actual fluid load line of the first set for the upstroke of the downhole pump from the values of the downhole pump data comprises calculating a zero of a first derivative of the downhole position in the upstroke of the downhole pump data.

6. The method of claim 1 , wherein determining, in the first determination, the actual fluid load line of the first set for the downstroke of the downhole pump from the values of the downhole pump data comprises calculating a concave up point after a transfer point in the downstroke of the downhole pump data.

7. The method of claim 6 , wherein calculating the concave up point comprises calculating an absolute minimum of a second derivative of the downhole position after the transfer point in the downstroke of the downhole pump data.

8. The method of claim 1 , wherein determining, in the second determination different from the first determination, the second set of calculated fluid load lines for the calculated fluid loads of each of the upstroke and the downstroke of the downhole pump from the values of the downhole pump data comprises calculating the second set of calculated fluid load lines statistically for upstroke load values and downstroke load values.

9. The method of claim 1 , wherein assessing the damping used to generate the downhole pump data by comparing the first set of actual fluid load lines to the second set of calculated fluid load lines comprises determining that the downhole pump data is over-damped or under-damped.

10. The method of claim 9 , wherein determining that the downhole pump data is over-damped or under-damped comprises determining the downhole pump data is over-damped by determining at least that (a) the upstroke calculated fluid load line of the second set is less than the upstroke actual fluid load line of the first set, (b) the downstroke calculated fluid load line of the second set is greater than the downstroke actual fluid load line of the first set; or (c) both (a) and (b).

11. The method of claim 9 , wherein determining that the downhole pump data is over-damped or under-damped comprises determining the downhole pump data is under-damped by determining at least that (a) the upstroke calculated fluid load line of the second set is greater than the upstroke actual fluid load line of the first set, (b) the downstroke calculated fluid load line of the second set is less than the downstroke actual fluid load line of the first set; or (c) both (a) and (b).

12. The method of claim 1 , wherein modifying at least one parameter of the pump apparatus based on the comparison comprises:
adjusting the damping of the wave equation model based on the comparison; and
generating another downhole pump data based on the adjusted damping.

13. The method of claim 1 , wherein modifying at least one parameter of the pump apparatus based on the comparison comprises stopping the motor or adjusting a speed of the motor.

14. The method of claim 1 , wherein the upstroke actual fluid load line of the first set is indicative of a top of stroke of the downhole pump, and wherein the downstroke actual fluid load line of the first set is indicative of a concave up point after transfer of the fluid load of the downhole pump.

15. The method of claim 1 , wherein the upstroke calculated fluid load line of the second set is indicative of distribution of load values in the upstroke of the downhole pump data, and wherein the downstroke calculated fluid load line of the second set is indicative of distribution of load values in the downstroke of the downhole pump data.

16. A controller for a pump apparatus having a downhole pump disposed in a wellbore and having a motor at a surface of the wellbore, the downhole pump reciprocated in the wellbore by a rod string operatively moved by the motor, 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 and storing a wave equation model having damping; and
a processing unit in communication with the one or more interfaces and the memory and configured to:
generate downhole pump data having values indicative of downhole load and downhole position of the downhole pump with the surface measurements and the wave equation model,
determine, in a first determination, a first set of actual fluid load lines for actual fluid loads of each of an upstroke and a downstroke of the downhole pump from the values of the downhole pump data, the actual fluid load lines being additional to the values of the downhole pump data;
determine, in a second determination different from the first determination, a second set of calculated fluid load lines for calculated fluid loads of each of the upstroke and the downstroke of the downhole pump from the values of the downhole pump data, the calculated fluid load lines being additional to the values of the downhole pump data and to the actual fluid load lines;
compare the actual fluid load lines to the calculated fluid load lines to assess damping used to generate the downhole pump data, and
modify at least one parameter of the pump apparatus based on the comparison.

17. The controller of claim 16 , wherein the processing unit is configured to:
initially obtain the surface measurements indicative of surface load and surface position of the rod string at the surface; and
measure the surface load and the surface position of the rod string at the surface or obtain the surface measurement from memory.

18. The controller of claim 16 ,
wherein to determine, in the first determ

Assignees

• Pons Victoria M
• Weatherford Tech Holdings Llc

Inventors

• Pons Victoria M

Classifications

• E21B47/009

  Monitoring of walking-beam pump systems · CPC title

• G05B13/042

  in which a parameter or coefficient is automatically adjusted to optimise the performance · CPC title

• F04B2201/1211

  Position of the walking beam · CPC title

• F04B2201/121

  Load on the sucker rod · CPC title

• F04B51/00

  Testing machines, pumps, or pumping installations · CPC title