Fracture Interference Effect on Shale Well Performance, RTA and Numerical Simulation Workflow with Economic Analysis

The cluster spacing was considered up to 700 ft in Barnett and Bakken shale formations. At this time, tight cluster spacing has been used up to 15 ft apart in Eagle Ford and DJ Basin. The drive for applying tight fracture spacing is to increase the initial production rate. However, a higher initial production rate is at the expense of higher operation and completion costs in addition to operational complexity. This study presents an integrated workflow to investigate the effect of cluster interference on well performance. Analytical rate transient analysis (RTA) was combined with reservoir numerical simulation to calculate the effective fracture surface area for hydrocarbon production. The ratio of the effective fracture surface area from RTA analysis to the actual stimulated fracture area from the numerical simulation will be correlated to the cluster spacing. The economic study was added to investigate the optimum spacing based on the profitability of the well. The results showed that the well with a higher stage number and tighter cluster spacing will have high cluster interference with low effective to actual fracture surface area ratio. In addition, the well will drain the production area near the wellbore faster with the high initial production rate but with high production declining rate. Increasing the cluster spacing, with the same injected proppant volume, shows an increase in the effective to actual fracture surface area ratio, and low cluster interference. A lower initial rate was observed with a low production declining rate. From the economic study, spacing of 60 ft was found to be the optimum spacing based on the formation properties, capital cost, and gas price. As the interest rate and gas prices increases, or low capital costs, the optimum completion tends to be with tighter spacing to accelerate the production. The results from this study will assist the completion and help reservoir engineers to optimize the cluster spacing to maximize the well revenue.