Abstract
The objective of this paper is to present a new method for estimating producing gas-oil ratios and solution gas production from shale volatile oil reservoirs. In order to enhance our knowledge about the production mechanisms of shale oil reservoirs and possibly better exploit their economic potential, it is important for us to be able to forecast production of the secondary phase – gas.
First, we simulated 30 years' production with different reservoir fluids using a commercial compositional reservoir simulator. We then analyzed producing gas-oil ratio data from several representative oil wells using principal components analysis (PCA). With the aid of the Principal Components Methodology (PCM), the principal components obtained from the analyses were used to forecast gas-oil ratios from wells with production histories ranging from 0.5 to 3 years and results were compared to simulated data. We then calculated the cumulative solution gas production from the estimated producing gas-oil ratios.
Stakeholders often focus on oil forecasts for shale oil reservoirs, ignoring the important solution gas produced from these plays. Limited production data, complex flow mechanisms in liquid-rich shale reservoirs, patterns of producing gas-oil ratios and other factors, make the task of forecasting solution gas production difficult. Principal components analysis (PCA) has enabled us to reveal the internal structure of data from the representative wells considered, in a way that best describes the variance in the data. This allowed us to get principal components (data from the PCA calculations) that helped us forecast gas-oil ratios from shale volatile oil reservoirs using the Principal Components Methodology (PCM). We were able to estimate producing gas-oil ratios and solution gas production with reasonable accuracy.
This work presents a unique and novel approach of forecasting production from liquid rich shale plays. It can help to improve reserves estimation, reservoir management and project economics.
