Utility and Reliability of Cemented Resistivity Arrays in Monitoring Waterflood of the Mansfield Sandstone, Indiana, USA

Abstract

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 observation well. This paper describes the utility of the data provided by the resistivity arrays and discusses data quality and reliability of the measurements. Two wells were drilled into the Mansfield sandstone reservoir in Indiana. 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, 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 about 20 B/D, increasing to 100 B/D after fracture stimulation. The D-8 array records responses to perforation, acidization, swabbing, fracturing, and injection. It clearly distinguishes the movement of the waterfront in different zones. The data show good signal-to-noise ratio and high reciprocity. The OB-1 electrical array clearly indicates early water breakthrough via an induced fracture. The arrays show no degradation of signal over the 17-month duration of the experiment. The experiment has demonstrated the viability of using permanently installed resistivity arrays to monitor movement of oil-water contacts 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. Introduction The industry drive toward using intelligent wells to improve recovery efficiency will require continuous monitoring and optimization of reservoir drainage. Currently, commercial monitoring is through sensors that measure flow in the wellbore and permanent borehole pressure gauges. These sensors allow for reactive reservoir management: opening or closing production zones as a response to 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, prior to 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 As 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.

A new numerical model of electrokinetic potential response during hydrocarbon recovery

“…(For this production rate, 50 m of movement of the water front represents approximately 100 days of production). The measured potential is well above the expected noise level of 0.1 -1 mV [Bryant et al, 2001], even when the water front is more than 200 m from the borehole. These values compare with maximum streaming potentials calculated by Wurmstich and Morgan [1994] of 32.8 mV for one-phase flow and 63.4 mV for two-phase flow.…”

“…[3] Since this work was published, downhole electrodes in cemented arrays, mounted at the production well on the outside of insulated casing, have been successfully applied in subsurface resistivity surveys during oil production [e.g., Bryant et al, 2001]. Similar technology could be used to measure electrokinetic potential.…”

Characterization of Reservoir Heterogeneity Through Fluid Movement Monitoring With Deep Electromagnetic and Pressure Measurements

“…ERA measurements will complement these existing measurements for in-situ formation characterization. ERA technology has previously been suggested and used to address such a need in reservoir charac-this work and the previous applications (van Kleef et al 2001;Bryant et al 2001;Bryant et al 2002) is that the ERA sensors were mounted on slotted tubing inside an openhole wellbore rather than being cemented on the outside of the casing. Although the measurements of the ERA sensors on tubing might have higher noise induced by the complicated wellbore flow environment than those of cemented sensors, the new string was much more flexible for field operation and particularly suitable for carbonate reservoirs in which an openhole completion is a common operational practice.…”

“…The history matching of the time-lapse ERA data confirmed the first pass estimates of the identified heterogeneities. terization and fluid movement monitoring (Belani et al 2000;van Kleef et al 2001). In the present study, the ERA technology was applied to the identification of formation heterogeneity in a typical Middle East carbonate reservoir.…”