A Novel Approach of Detecting Water Influx Time in Multi-Zone and MultilateralCompletions using Real-Time Downhole Pressure Data

Abstract

1. Abstract Increasing use of advanced (intelligent) completions has provided the facility for real time reservoir monitoring through use of permanent downhole instrumentation and control of production from different zones within the reservoir through use of surface operated inflow control devices. The potential for the real-time data generated by advanced completion solutions is now being exploited to a greater extent The paper will demonstrate that trending analysis of the pressure drop (dP trending) using the data delivered by sensors located strategically in a multi-zone horizontal or multilateral intelligent completion can identify the time and location of water influx into a well. It will be shown that "pressure drop trend signatures" can identify the location of the water influx and application of this approach will be illustrated by use of two, three and four zone completions in synthetic reservoirs. A more complex, field based example will also be employed to illustrate the robustness of the technique. Prompt recognition of the influx of unwanted fluid and its location can be achieved using the technique described in this paper. 2. Introduction Advances in drilling and completion technology during the last twenty years have aided the delivery of increased well productivity and reservoir drainage efficiency. The advent of multilateral and maximum reservoir contact wells has added a further dimension to these recovery techniques 1, 2 Early detection of unwanted water or gas production and the knowledge of the point of influx allows for prompt remedial action, by for example, re-direction of injection water. The use of downhole instrumentation such as pressure and temperature sensors has provided one of the necessary tools to assist in real-time optimisation of well performance. Intelligent well completions offer a combination of well performance monitoring, zonal productivity control and subsequent well production optimisation3, 4, 5 and are one of the steps in the realisation of the vision of Real-Time Optimisation in oil and gas field operations. Real-Time Optimisation enables operations to be transformed by downhole sensor and data transmission systems delivering real-time information and allowing rapid reconfiguration of the completion to optimise production. The resulting step change in the efficiency of the production process is the target that many companies are striving for as they introduce their variant of this vision under acronyms such as: Smart Fields, Digital Oil Field, i-field, e-field, Fields of the Future. The intelligent field concept has matured to such an extent in the last decade that several major operators now have fields where intelligent technologies have been deployed on a large scale6, 7 Field deployment has been facilitated by the rapid development of measurement and information technologies such as: Field applications have been reported that illustrate the value that can be derived from the systematic use of real-time data 9, 10, 11 Permanent downhole pressure sensors installed in advanced completions can be used to determine differential pressures between any two adjoining zones. This paper will show how the analysis of the pressure drop trend or gradient can be used to determine information on the time and location of a water front arriving at a production well.