Production Technology Experience in Michigan Waterfloods

Abstract

Summary Waterflooding started in the Niagaran carbonate reef oil reservoirs in northern Michigan in 1978 with Shell Oil Co.'s Chester 18 waterflood. Ten waterflood projects had been installed by Spring 1983. As a result of this experience, significant production technology practices have become established. The majority of the waterflood experience has been in Shell's Gaylord Production Unit located primarily in Otsego and Crawford counties. Specifically, the projects discussed are the Chester 18, Chester 21, Frederic 10, Hayes 15, Hayes 21A, and Mid-Charlton 10 waterfloods. In general, the waterflood program can be characterized by (1) very favorable oil program can be characterized by (1) very favorable oil production response, (2) timely and definitive production response, (2) timely and definitive surveillance techniques, (3) systematic and timely well work on injectors and producers to maintain optimum reservoir withdrawal behavior, (4) innovative application of artificial lift technology, and (5) aggressive future planning to maintain and to improve oil production response. planning to maintain and to improve oil production response. This paper elaborates on these waterflood program characterizations as follows.The favorable impact that waterfloods have had on oil production is discussed.The frequency and type of surveillance techniques are described for both injectors and producers. Some of the major techniques are pressure transient analysis, inflow performance plots, produced water cut and water weight records, injection and produced fluid analysis, hydrogen sulfide monitoring, reservoir withdrawal calculations, injection profile surveys, and well-to-well radioactive tracers.As a result of the surveillance techniques, well treatments have been designed for salt, calcium carbonate scale, gypsum scale, paraffin, and bacterial wellbore impairment. Surveillance has also resulted in continuous chemical injection programs to combat corrosion, scale, salt, oil/water reverse emulsions, bacterial formation, and H, S formation. The constant calculation of reservoir withdrawals has led to alterations in the various project operating policies.Withdrawal surveillance, inflow performance monitoring, and reservoir simulation have indicated that greater ultimate recovery, maximum operating income, and maximum present value profit will be achieved in spite of increasing volumes of water with high fluid withdrawals. Recent improvements in submersible pump technology (rotary gas separator and variable speed control) have enabled high withdrawal rates to be achieved efficiently (3,000 to 4,000 B/D [477 to 636 m'/d] fluid).An aggressive program for future activity has necessitated considerable short- and tong-term planning. Items such as facility sizing, disposal zone testing, produced water handling, electric power supply for northern produced water handling, electric power supply for northern Michigan, and source water development are some of the major items that have been studied. Introduction Waterflooding was initiated in a Niagaran carbonate reef oil reservoir in northern Michigan in 1978. Ten projects throughout the reef trend had been installed by Spring 1983. As a result of this experience, effective production technology practices have become established. This paper reviews the major production technology paper reviews the major production technology surveillance techniques and highlights some of the results. The Silurian Niagaran reefs, in which there are 600 separate fields, are located along the northern rim of the Michigan basin. Fig. 1 shows the reef trend with the locations of the five major waterflood projects. The reservoir consists of dolomite and limestone rock of the Silurian Niagaran reef and the overlying A-1 carbonate. The reservoir seal is an anhydrite bed called the A-2 evaporite. A more complete description of the carbonate reef geology is offered by Huh et al. A recent discussion of the total Niagaran reef play is given by Aminian et al. The size of the Niagaran reefs under waterflood range from 50 to 560 acres [202 344 to 2 266 249 m2 ]. The smallest has only two wells, whereas the largest has 20 wells. The design and operating programs initially planned for the waterflood projects have proved planned for the waterflood projects have proved successful. The operating data from the more mature projects have enabled development of effective production projects have enabled development of effective production technology practices. The projects discussed specifically are the Chester 18, Chester 21, Frederic 10, Hayes 15, Hayes 21A, and the Mid-Charlton 10 waterfloods that are operated by Shell Oil Co. in Otsego and Crawford counties. This paper reviewsthe favorable effect waterflooding has had on oil production;the frequency and type of production surveillance techniques;the results of some of these techniques;artificial lift considerations; andfuture planning of more waterflooding in the northern Michigan reef trend. Effect of Waterflooding on Oil Production Waterflooding has substantially increased oil production in the past 3 years. JPT P. 1446