Applying Innovative Production Modeling Techniques to Quantify Fracture Characteristics, Reservoir Properties, and Well Performance in Shale Gas Reservoirs

Abstract

In order to more accurately characterize reservoir and hydraulic fracture properties from well performance, a workflow has been developed that effectively integrates variable quality data from a variety of sources. This workflow applies analytical techniques designed specifically for shale gas wells followed by as-needed numerical modeling. The analytical techniques can be applied to multiple wells through time to: a) identify groupings of like-performing wells, b) detect wells with anomalous behaviors, c) develop hypotheses about production mechanisms, and d) choose specific wells for more detailed analysis and numerical modeling. Numerical modeling provides the functionality needed for complex mechanism forensics, performance forecasting, and completion optimization studies. Conventional numerical models typically use finite-difference grids, but these are neither sufficiently complex nor sufficiently flexible for shale gas reservoirs. For this reason, a finite-element modeling technology has been applied that places a large number of closely-spaced nodes near hydraulic fractures, "where all the action takes place" in the early life of a well. The finite-element technique also allows complex fracture geometries to be modeled. This workflow, incorporating analytical and numerical solutions, has been applied to multiple shale gas projects, including industry consortia in the Haynesville (US) and Montney (Canada) shales and individual operator projects in the Woodford (US), Horn River (Canada), and Marcellus (US) shales. Through the application of these techniques, fracture and reservoir properties have been characterized and uncertainty associated with forecasted well performance has been reduced. This work has profound implications for quantifying gas reserves, understanding those factors responsible for variations in well performance, and for optimizing well spacing, lateral lengths, and completion techniques.

Production data analysis of tight gas condensate reservoirs

“…Several studies (Ibrahim and Wattenbarger, 2006, Poe, 2002, Miller et al, 2010and Nobakht and Clarkson, 2012 focused mainly on the flow of single phase gas to obtain the linear flow parameter, x f √k. Ibrahim and Wattenbarger noted that the transient linear flow solution, derived for liquids, required the use of pseudopressure and empirical drawdown factor to account for changing gas properties with pressure.…”

The RealGas and RealGasH2O options of the TOUGH+ code for the simulation of coupled fluid and heat flow in tight/shale gas systems

“…Miller et al, (2010) and Jayakumar et al, (2011) used numerical simulation to history-match and forecast production from two different shale-gas fields. Cipolla et al, (2009), Freeman (2010, 5 Moridis et al, (2010) and Freeman et al, (2009; and conducted numerical sensitivity studies to identify the most important mechanisms and factors that affect shale-gas reservoir performance.…”

A Better Understanding of Finite Element Simulation for Shale Gas Reservoirs through a Series of Different Case Histories

“…Once the data have been processed, the next step is the analytical analysis. Miller (2010) details the analytical analysis formulation and workflow for shale gas reservoirs. Analytical modeling limits the range of uncertainty in critical parameters such as matrix permeability, fracture spacing, and fracture surface area governing the well performance.…”

“…The fracture pattern is defined as geometry of propped fractures that may have been created during the stimulation process and includes the natural fractures contributing to flow. A complex fracture network will have a large apparent fracture surface area during the internal linear transient flow period (Miller, 2010). After fracture interference occurs, the well exhibits a quasi-steady state boundary dominated flow.…”