Evaluation of Historical and Ongoing Double Displacement Process in Yates Field Unit

Abstract

Implementation of a second Double Displacement Process (DDP2) has been evaluated for Yates Field Unit (YFU). A DDP2 Demonstration Area Project has been designed to test DDP2 in a mature, high recovery area of the field. A detailed, geologically based reservoir description was used to build a simulation model for the DDP2 pilot area to study the DDP process and evaluate DDP2 performance. Initial saturations and relative permeability curves were generated based on a capillary pressure based Saturation Height Function (SHF) study. The fracture system was simulated using a hybrid dual porosity/permeability system. A 9-component equation of state (EOS) was used to model the YFU fluid properties. Capillary pressure of imbibition is used to capture the effect of hysteresis and oil trapping in the zones invaded by the aquifer during primary depletion. The simulation model has been tuned against historical performance since 1927, focusing on the first DDP process (DDP1) implemented over 1992-2000. Matching historical production/injection, field pressure and fluid contacts data were the history matching objectives. The DDP2 pilot project will include lowering 31 Horizontal Drain Hole (HDH) lateral completions by 25 feet to lower the contacts. The tuned model has been used to generate flow streams for different forecasting scenarios utilizing the DDP2 process. Forecast results show incremental oil recovery by lowering the contacts by 25 feet during the DDP2 phase. This paper presents a comprehensive study of YFU DDP1 process and evaluation of the second DDP process by a 3D numerical simulation model. The simulation model is used to improve understanding of the complex Gas-Oil Gravity Drainage (GOGD) and Gas Assisted Gravity Drainage (GAGD), and provide forecasts for the DDP2 process. Success of the pilot will result in extending the field life another 10-20 years.