Application of Dead Oil Viscosity for Water Shut-Off Job Designs in Reservoirs with Biodegradation: A Case Study of Bhagyam Field

Abstract

Abstract This paper demonstrates a novel technique of tracking water entry zones, which has been used with a good success rate in Bhagyam field. Bhagyam field is located in the state of Rajasthan, India and is a part of the prolific Barmer Basin. Oil Production from Bhagyam field has shown steep decline as the water cut increased sharply. The reason for the increase in water cut can be largely attributed to adverse mobility ratio and limited volumetric pump capacities which limit drawdown. The excess water not only has reduced oil rates but also increased liquid volumes at the processing terminal. In order to control operating costs and increase oil production, it was of paramount importance for the operator to carry out water shut off jobs as a measure to reduce the undesirable water production. This paper illustrates firstly a systematic approach on how the water entry zones are identified with the help of dead oil viscosity data and secondly describes a few case histories of water shut off jobs. Mechanical water shut off techniques were used to isolate bottom watered out sands temporarily. Retrievable bridge plugs were installed above the watered out zones during work-overs to increase drawdown on other sands and increase oil recovery. Using this methodology, four water shut off jobs were executed successfully in FY 2014–15 which led to significant reduction in water production and subsequent increase in oil production.