An Application of Cemented Resistivity Arrays To Monitor Waterflooding of the Mansfield Sandstone, Indiana, U.S.A.
- I.D. Bryant (Schlumberger-Doll Research) | M.-Y. Chen (Schlumberger-Doll Research) | B. Raghuraman (Schlumberger-Doll Research) | I. Raw (Schlumberger Reservoir Completion Center) | J.-P. Delhomme (Schlumberger Riboud Product Center) | C. Chouzenoux (Schlumberger Riboud Product Center) | D. Pohl (Schlumberger Riboud Product Center) | Y. Manin (Schlumberger Riboud Product Center) | E. Rioufol (Schlumberger Riboud Product Center) | G. Oddie (Schlumberger Cambridge Research) | D. Swager (Team Energy LLC) | J. Smith (Team Energy LLC)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- December 2002
- Document Type
- Journal Paper
- 447 - 454
- 2002. Society of Petroleum Engineers
- 4.1.2 Separation and Treating, 5.7.2 Recovery Factors, 1.14 Casing and Cementing, 5.1 Reservoir Characterisation, 2.3 Completion Monitoring Systems/Intelligent Wells, 3.3.1 Production Logging, 3.3 Well & Reservoir Surveillance and Monitoring, 5.8.7 Carbonate Reservoir, 5.3.2 Multiphase Flow, 3.1.1 Beam and related pumping techniques, 4.3.4 Scale, 4.1.9 Tanks and storage systems, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 3 Production and Well Operations, 5.6.1 Open hole/cased hole log analysis, 2 Well Completion, 5.1.5 Geologic Modeling, 5.6.4 Drillstem/Well Testing, 1.6.9 Coring, Fishing, 4.1.5 Processing Equipment, 1.6 Drilling Operations, 6.5.2 Water use, produced water discharge and disposal, 5.2 Reservoir Fluid Dynamics, 5.4.1 Waterflooding, 2.2.2 Perforating, 3.2.4 Acidising
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In 1999, an oilfield experiment was initiated to test the application of electrical measurement technologies to permanent reservoir monitoring. The principal objective of the experiment was to demonstrate the feasibility of monitoring water movement between an injection and an observation well. This paper describes the interpretation of the data provided by the resistivity arrays and discusses the data quality and reliability of the measurements.
Two wells were drilled into the Mansfield sandstone reservoir in Indiana, U.S.A. The D-8 injector well was located in the center of four development wells. The OB-1 monitoring well was offset 233 ft to the southwest in a location midway between the D-8 injector and the No. 3 production well. The injector was instrumented with a 16-electrode resistivity array that was run on the outside of insulated casing and cemented into the annulus of the well. A similar array was cemented into the annulus of the monitoring well.
In March 1999, the D-8 well was perforated and acidized. A surface gauge was used to monitor injection rates and pressures. Initially, injection proceeded at a rate of approximately 20 B/D, increasing to 90 B/D after fracture stimulation. The D-8 array records responses to wellbore operations and injection. It clearly distinguishes the movement of the waterfront in different zones. The OB-1 electrical array clearly indicates early water breakthrough by means of an induced fracture. The data show good signal-to-noise ratio and high reciprocity.
The experiment has demonstrated the viability of using permanently installed resistivity arrays to monitor the movement of oil/ water contacts and salinity fronts that are some tens of feet away from the wellbore. Results demonstrate the feasibility of using such arrays to monitor oil/water contact movements remote from injection, monitoring, and production wells.
The industry drive toward using intelligent wells to improve recovery efficiency will require continuous monitoring and optimization of reservoir drainage. Currently, commercial monitoring is done through sensors that measure flow in the wellbore and in permanent borehole pressure gauges. These sensors allow for reactive reservoir management (opening or closing production zones as a response to the breakthrough of unwanted fluids into the wellbore). Proactive reservoir management is possible if we are able to detect the advance of unwanted fluids in the formation before their breakthrough into the production stream. We have conducted an oilfield experiment to demonstrate that sensors can be deployed and used to monitor fluid movement remote from the wellbore.1 Because this was the primary objective of the experiment, emphasis was placed on demonstrating the feasibility and utility of such measurements, rather than on testing a commercially viable deployment scheme.
In January 1999, an injection well, D-8, was drilled in a shallow producing oil field in Indiana (Fig. 1) and instrumented with a 16-electrode resistivity array that was cemented into the annulus of the well (Fig. 2). The lowest eight joints of casing were coated to insulate the casing and to prevent short-circuiting of the electrode array through the casing. Flooding of the site caused further activity to be delayed until early March, when a monitoring well, OB-1, was drilled 233 ft to the southwest and instrumented with an identical electrical array and a pressure gauge that was also cemented outside the casing of the well.1,2 The injection well was equipped with a portable ultrasonic surface flowmeter to monitor the water-injection rate. A strain gauge was used to monitor the surface injection pressure. The electrical arrays and downhole and surface gauges were interrogated remotely though acquisition systems housed in a small hut installed on site and connected to our local office by standard phone lines.
The D-8 injector was used to inject approximately 18,400 bbl of water during the remainder of 1999, and both the electrode arrays and the gauges were monitored throughout this period. Initially, water was injected at 20 B/D to allow many acquisition cycles during the early period of the waterflood. However, after several days, injectivity of the formation dropped, and it was necessary to hydraulically fracture the well. Thereafter, injection proceeded at rates of up to 90 B/D, with short transient flows exceeding this rate when injection recommenced after shut-in periods. Data analysis in the latter part of the year indicated that water was arriving at the monitoring well through an induced fracture.
Background to the Ashworth Lease
The Ashworth lease is close to the Indiana-Illinois border in Posey County, Indiana. Now operated by Team Energy LLC, it was initially developed during the 1980s and early 1990s on 10-acre spacing. Team Energy recently drilled infill wells to convert the original pattern of wells, which were drilled for primary drainage, to a five-spot pattern, in which each injector is centrally located with respect to four surrounding production wells (Fig. 1). The previous operator was concerned with the possibility of bottomwater causing production wells to water out prematurely; consequently, not all wells are perforated across the full formation thickness. All production wells are rod pumped. Some pumps are on timers and only operate intermittently. Production is not monitored on an individual well basis but is measured at the gathering station. Injection water is drawn from a shallow aquifer but is supplemented periodically by the reinjection of produced water from the storage tanks. The reservoir has been produced for almost 20 years and is significantly depleted.
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