New and Improved Methods for Performing Rate-Transient Analysis of Tight/Shale Gas Reservoirs
Date
2014-09-23
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Abstract
Analysis of long-term linear flow periods associated with tight/shale gas production has received much attention in recent literature as a means of obtaining information about stimulation efficiency (for example, the product of fracture half-length and square root of permeability referred herein as the linear flow parameter). In this study, first, new methods for analyzing production data from a fractured well in tight/shale gas reservoir producing under a constant flowing pressure, a constant production rate and variable flowing pressure/production rate in the absence or presence of desorption and gas-slippage are presented. It is shown that the current formulation of linear flow analysis results in an overestimation of linear flow parameter for constant flowing pressure production. It is also found that the shape of square-root-of-time plot depends on the production rate for constant gas rate production.
Secondly, the effects of completion heterogeneity (i.e., all fracture lengths are not the same) of a multi-fractured horizontal well (MFHW) are studied and a method is developed for extending hybrid forecasting methods developed for homogeneous completions to heterogeneous completions. The methodology developed is also applied for multi-well analysis of MFHWs. It is found that ignoring the heterogeneity of the completion can have a large impact on the long-term forecast of these wells.
Thirdly, a new set of dimensionless type curves is developed for one of the most commonly used conceptual models for MFHWs. With these dimensionless type curves, the early linear flow (early-time half slope) and boundary-dominated flow (late-time unit slope) coincide for different geometric ratios and the transition between these two regimes depends on the geometry of the reservoir and completion.
Finally, the applicability of flowing material balance (FMB) analysis for calculating contacted gas-in-place (CGIP) in linear-flow dominated systems is investigated. It is found that even when dealing with a gas reservoir that is depleted significantly, FMB underestimates the original gas-in-place (OGIP). We also investigated whether applying a corrected material balance pseudo-time, calculated using the average pressure in the region of investigation as opposed to average reservoir pressure, will correct for underestimation of OGIP for the case that the reservoir is significantly depleted.
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Engineering, Engineering--Petroleum
Citation
Nobakht, M. (2014). New and Improved Methods for Performing Rate-Transient Analysis of Tight/Shale Gas Reservoirs (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27091