Detecting Water Influx in Beam Pump Lifted Horizontal Wells in a South Oman Field Uing Temperature Measurements, Production Profiling, and Concentric Coiled Tubing

Abstract

Abstract Strong bottom water drive, high matrix permeability and complex fracture and fault networks have resulted in a significant water influx problem in a South Oman field. The majority of wells produce with a water cut of at least 90% and some new wells are experiencing early water break-through. To combat this problem, swelling elastomers (SE) on wire-wrapped screen (WWS) completions have been used since early 2004 to provide reservoir segmentation behind the horizontal completion. Open hole logging and/or underbalanced drilling are used to determine where the elastomers should be placed. Reservoir segmentation allows mechanical water shut-off methods (i.e. scab liners, clads and bridge plugs) to be employed. Older wells that do not have elastomers will require chemical water shut-off treatments. Water shut-off (WSO) will enable redirection of reservoir and artificial lift energy to oil producing zones and hence maximize oil production and ultimate oil recovery. However, before an effective WSO treatment can be applied, the location of water breakthrough, (due to coning or a conductive fracture or fault) has to be determined. Most of the wells are artificially lifted using beam pumps which represent a barrier and a great challenge to surveillance activities under dynamic conditions. Concentric coiled tubing (CCT) and a specialized jet pump or vacuum tool has been utilized to overcome this problem. The technique combines concentric coiled tubing vacuum technology (CCTVT) with a pressure and temperature memory gauge. A procedure has been developed to utilize static and dynamic well conditions to determine water entry points: The static temperature indicates fluid migration behind the horizontal completion and gives the history of water movement from the reservoir to wellbore.The geothermal gradient is measured and compared to the static temperature – this indicates where warmer fluids are migrating from below (aquifer).The specially designed jet pump on CCT creates a localized drawdown and a steady state flowing condition.The temperature measured during the dynamic production period is compared to the static temperature to indicate the current flow of reservoir fluids.Surface sampling to measure water cut is correlated with depth to corroborate the temperature data. This paper will present case histories of the profiling technique along with results and conclusions. It will also compare the response from this technique to normal production logging.