Infill-Drilling Potential in Tight Gas Reservoirs

Abstract

Many operators of tight gas reservoir fields are interested in determining the infill well potential in these fields. Over drilling may prove to be uneconomical; whereas, under drilling would leave unexplored reserves under the ground. In predicting FUR (expected ultimate recovery) of a potential infill well, operators are interested in knowing what percentage of the production will be come from incremental reserves (newly accessed) and what percentage is from acceleration reserves (which can be produced from existing wells). So. higher the percentage of incremental reserves better is the potential of an infill well, ln this paper, we present a novel method for determining the incremental versus acceleration potential for infill well in a tight gas reservoir. We evaluate the existing wells by plotting the data in a form so that the data can be linearly extrapolated. Then, we can predict the FUR for individual wells before and after new wells in the vicinity are drilled. By knowing how much gas is "diverted" from the older wells, we determine the acceleration component of an infill well. By repeating the process as the field is being developed, we can determine the fraction of acceleration and incremental components of the EUR at each stage of infill drilling. We will also know how the EUR is changing as the well spacing is slowly reduced. To ensure our results are reasonable, we also compare our FUR values with FUR's reported by the operator as proved reserves. Armed with this information, we can extrapolate infill well potential for a smaller spacing, including the contribution due to acceleration versus incremental production. We applied this procedure for Wamsutter field in Wyoming. Using the procedure, we recommended infill well locations to the operator. Operator has drilled seven wells based on our recommendations. Using this new method, we can predict the FUR for infill well as well as acceleration and incremental contribution of the infill well. Thus, potential of infill wells at different locations can be evaluated and compared.

Enhanced Gas Recovery for Tight Gas Reservoirs with Multiple-Fractured Horizontal Wells in the Late Stages of Exploitation: A Case Study in Changling Gas Field

“…The mechanisms for these methods are the increasing in production degree of reserves, pressure drawdown sweep efficiency and pressure depletion efficiency [10][11][12]. Currently, for tight gas reservoirs exploited with vertical wells, the technologies for infilling wells for EGR have been presented, which are mainly based on the quantitative geological model, the dynamic drainage area, the ratio of inter-well interference, the dynamic inversion of numerical simulation and the critical well space [13][14][15][16][17][18][19][20][21]. For tight gas reservoirs developed by MFHWs, to improve the gas recovery, the methods of side tracking for old wells and placement optimization for new infilling wells have been presented [22][23][24][25][26].…”

A workflow for flow simulation in shale oil reservoirs: A case study in woodford shale

“…Some authors have used commercial reservoir simulators to study the gas production from a shale gas reservoir in an integrated workflow (Cipolla et al, 2010). Luo and Kelkar (2013) presented a new approach to predict the expected ultimate recovery of infill well in the tight gas reservoirs. Osholake et al (2013) investigated the factors that affect the performance of hydraulically fractured well in the Marcellus shale.…”