Abstract
In March 2021, the Alberta Energy Regulator (AER) introduced a new directive on pressure and deliverability testing, providing updated guidelines for inline testing to match industry practices. The AER now receives from oil and gas operators flowback data from inline tests and absolute open flow (AOF) interpretations. After analyzing this data, the AER has developed best practices. Best practices resulting from this study are contrasted to published studies of the Duvernay Formation.
Currently, the AER cannot obtain fracture geometry and other fracture parameters. With the addition of pressure data, this study will aid the AER in obtaining fracture geometry, such as half-length, and fracture parameters, such as stimulated reservoir volume (SRV), permeability and productivity parameters. The new interpretation will aid and enhance reserves assessment and improve our understanding of inter-wellbore communication. New descriptions using mathematical (analytical/numerical) methods allow improved design of completions and enhanced characterization of the reservoir. This technical paper provides fundamental equations along with inline test and AOF interpretation techniques, which can be easily replicated by subject matter experts.
Eighty unconventional flowback submissions were analyzed and displayed for non-vertical and non-deviated wells in the Duvernay. Productivity indices were calculated using flowback information and the AOF-based C value-related index of productivity (PI). Fracture geometry, SRV permeability, and PI estimates all significantly affect characterization of the reservoir. Currently, the AER only uses production rates in its flagship report AEO. This study will enhance the Duvernay reserves evaluation by using rate transient analysis (RTA) along with pressure parameters, such as tubing/casing pressure. Results from the study will affect what industry could do not only in the Duvernay but also in similar low-permeability resource plays in the United States of America and elsewhere. Production and pressure data aids in the interpretation of flow regimes to determine the optimal separation between wells and designs of completions.
Flowback information has been used before. However, our work is novel in how it applies to the Duvernay Formation, which has been target of many companies in Alberta, and the implications on reserves evaluation, completion design, and characterization of the reservoir.
