Production Performance Analysis of Unconventional Gas Reservoirs with Different Well Trajectories and Completion Techniques

Summary Various models featuring horizontal wells with multiple fractures have been proposed to characterize flow behavior over time in tight gas systems and shale-gas systems. Currently, little is known about the effects of nonideal fracture patterns and coupled primary-/secondary-fracture interactions on reservoir performance in unconventional gas reservoirs. We developed a 3D Voronoi mesh-generation application that provides the flexibility to accurately represent various complex and irregular fracture patterns. We also developed a numerical simulator of gas flow through tight porous media, and used several Voronoi grids to assess the potential performance of such irregular fractures on gas production from unconventional gas reservoirs. Our simulations involved up to a half-million cells, and we considered production periods that are orders of magnitude longer than the expected productive life of wells and reservoirs. Our aim was to describe a wide range of flow regimes that can be observed in irregular fracture patterns, and to fully assess even nuances in flow behavior. We investigated coupled primary/secondary fractures, with multiple/vertical hydraulic fractures intersecting horizontal secondary "stress-release" fractures. We studied irregular fracture patterns to show the effect of fracture angularity and nonplanar fracture configurations on production. The results indicate that the presence of high-conductivity secondary fractures results in the highest increase in production, whereas, contrary to expectations, strictly planar and orthogonal fractures yield better production performance than nonplanar and nonorthogonal fractures with equivalent propped-fracture lengths.

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Production Performance Analysis of Unconventional Gas Reservoirs with Different Well Trajectories and Completion Techniques

10.2118/spe-172944-ms ◽

2015 ◽

Author(s):

Mehmet Cihan Erturk ◽

Caglar Sinayuc

Keyword(s):

Shale Gas ◽

Synthetic Data ◽

Gas Production ◽

Production Performance ◽

Coal Bed ◽

Gas Reservoirs ◽

Case Scenario ◽

Unconventional Gas ◽

Future Production ◽

Unconventional Gas Reservoirs

Abstract The significance of unconventional gas reservoirs has been increasing for recent years owing to economic viability of their development, therefore assessment of the challenges and common pitfalls regarding those resources have been gaining importance at the same time. In this regard, the optimization of production performance of these reservoirs with the different well trajectories and completion techniques and identifying the best case scenario become more significant. That is absolutely challenging process due to the several reasons such as ultra-low permeability, desorption effect, and complex geological characteristics. However, it is possible to analyze the various parameters and observe their impact on each system with the help of advances in algorithms, computer power, and integrated software. The objective of this work is to investigate and understand the effect of some reservoir and completion parameters on the future production performance of shale gas and coal bed methane (CBM) reservoirs. A practical model is constructed with the field and synthetic data for the analysis of gas production rate and cumulative gas production versus time in multi-layered shale gas and CBM reservoirs respectively. Changes in the thickness of various stratified layers, permeability, wellbore position, number of hydraulic fracture stage, and also production profile of each system are studied using different well trajectories. The results are obtained by running a series of reservoir simulation conducted by a commercial numerical simulator with dual porosity model for CBM and shale gas reservoirs.

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