Pump-Off Control, The Average Motor, Current Method
Authors: Hudgins T.A. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., April 7–9, 1975. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Introduction

Ever since oil well pumps were first used in their crudist form, there has been a need for controlling the pump. The controlling effort has been directed at matching the pump capacity with the well capacity. This type of control has been an objective of oil producers around the world. The value of achieving this goal has changed as the importance and value of crude oil has changed. The present conditions have placed a very high value and degree of importance on the amount of fluid produced and the lifting costs necessary to produce that fluid.

Many of the pumping problems that occur in the production of oil can be traced back to the lack of proper pump control. Some of these problems include gas locks, mechanical damage problems include gas locks, mechanical damage to the pump, rods, gear box and excessive power consumption. With rising costs, to correct the above problems proper control of pumps has become increasingly important. There has been a decrease in the amount of manpower available to trace down these pumping problems, identify them and correct them. Most oil producing fields are being operated with fewer people today than they were several years ago.

During the years a number of methods have been tried in an effort to properly control pumping wells. These methods fall into two pumping wells. These methods fall into two basic categories - fluid production measurement and load measurement. Various types of equipment have been developed during the last 20 years in order to properly control pumping oil wells. Some of the design and equipment met with various degrees of success while other equipment and design met with total failure to meet the desired objective.

This paper considers some of the drawbacks of previous developments and discusses at length the development of the average motor current method of controlling oil well pumps. Following the development of this method, complete field tests and laboratory tests were run over an extended period of time to prove the method. Conclusions reached as a result of the design and testing program are stated in the conclusions of this paper.

PREVIOUS METHODS PREVIOUS METHODS Previous efforts to properly control oil well pumps range from very crude to very complex approaches. Obviously all of these approaches cannot be discussed in this paper. Some of the better known methods will be discussed to show the basic need for an improved method. The most common approaches are (1) to monitor the load, and (2) to monitor production rate.