An Innovative Approach to Understanding Shale Gas Well Behavior Based on a Performance Catalogue Fingerprint

Abstract

Abstract Shale gas wells performance is governed by the interaction between reservoir rock and the completion. However, external factors such as liquid loading, inefficient completion, and in some cases offset wells, can also influence performance. The large volume of shale gas wells necessitates the development of quick diagnostic tools. The linear transient flow behavior is well documented in shale gas wells; however, the post-linear transient flow behavior and the impact of non-reservoir phenomena are not. The objective of this paper is to provide a signature catalogue based on well performance fingerprints to quickly diagnose well history for dominant production mechanisms. To build the catalogue, both synthetic models and actual well history were used. All the data generated were analyzed using a consistent in-house shale gas workflow. This paper documents well performance signatures for various reservoir and non-reservoir phenomena. The synthetic models provided a controlled basis to study for aspects of reservoir and completion phenomena difficult to measure in the field such as the sequence of flow regimes, the impact of different completion configurations, pressure dependent permeability and conductivity, as well as fracture complexity. Actual field histories from various shale gas plays were used to study the impact of processes that are normally observed in field data but are difficult to predict by a model such as liquid loading, fracture cleanup, data quality and impact of artificial lift. The signature catalogue shows impact of different completion configuration and reservoir phenomena during the periods of constant linear transient productivity index and on the decline in productivity index once the fracture interference starts. The impact of inadequate completion cleanup is captured on the linear flow plot as a completion resistance factor. The impact of shut-in, diagnostics for liquid loading, and inconsistent or questionable data has also been analyzed. The behavior of the wells with complex fracture geometries, pressure dependent permeability and pressure dependent completion properties is also catalogued. This fingerprint catalogue is a valuable resource for the engineer as it allows for prompt identification of abnormal well behaviors and provides a diagnostic method for identifying various production mechanisms.