Vertical Turbine vs Positive-Displacement Pumps Used in Waterflood Operations

Abstract

Abstract Experience with can turbine installations as waterflood injection pumps indicates that where pumping requirements exceed 6,000 BID at pressure differentials less than 1,000 psi, an installed cost savings over plunger-type pumps is realized. The inherent flexibility in operating characteristics of the turbine-type pump makes the handling of variations in output volume or pressure a simple speed-control operation. Operating cost data collected for the first three years of can turbine operation on large-volume low-pressure flood, favor can turbine-type operation over reciprocating-plunger-type equipment. Introduction Over the last 10 years, waterflood projects have assumed a major role in oilfield operations, and a substantial portion of oil company investments has been allocated for such projects. To gain the greatest return from these investments, operators have been constantly striving to obtain the most economical injection equipment which will still provide maximum flexibility. Pan American Petroleum Corp., over the past three years, has installed 14 vertical turbine pumps in waterflood projects in the West Texas- New Mexico area in order to evaluate the features offered by such pumps. The purpose of this paper is to present an economic and operating comparison of vertical turbine pumps with the more commonly used positive-displacement pumps as applied in large-volume floods with both high and low injection pressures. Future operating cost data under greater load conditions and longer operating periods may reveal some disadvantages of the equipment not apparent at the time of this paper. History Pan American's first vertical turbine installation was completed in June, 1960, when a 13-stage pump was Put into operation in the Foster-South Cowden water-injection system near Odessa, Tex. Fig. 1 shows the location of this installation and other Pan American turbine installations. The Foster-South Cowden pump was designed to handle 27,000 BWPD at a maximum discharge pressure of 400 psig. This pump has now handled approximately 15 million bbl of various types of waters, including salt water, at a continuous discharge pressure of approximately 400 psig. In April, 1962, increases in injection pressure required the addition of a second pump in series with the first pump to boost final pump discharge pressure to 800 psig at the same rate. Fig. 2 shows this series turbine installation. A third turbine, which serves a separate injection system with 10,000 BWPD at a pressure of 600 psig, has been installed at this station (see Fig. 3). In Sept., 1961, two vertical turbine pumps were installed in the Corsica Unit, Stonewall Co., Tex. This was to be a four-pump installation at maximum design conditions, with all four pumps installed in series. This project differed from the Foster-South Cowden flood in that estimated final injection pressures would reach 3,000 psig. Each of the first two pumps was designed to handle 10,000 BWPD, with each pump raising the pressure 750 psi. The third pump was installed in this system in Nov., 1962, increasing plant pressure from 1,500 to 2,250 psig. Since installation of the third pump, injection pressures have reached 2,600 psig. The three present pumps have met this pressure while injecting approximately 1,500 BWPD. These pumps have now injected a total of 1.85 million bbl of water. A third waterflood project, utilizing two turbines, was initiated in the Northeast Hogback Unit, Horseshoe Gallup field, San Juan Co., N.M., in Dec., 1961. The two turbine pumps were installed in series and were designed to deliver 10.000 BWPD at a combined pressure of 1,000 psig. The total volume handled by these pumps is 1.8 million bbl. JPT P. 139ˆ