Sustainable development of unconventional resources: Analysis of the transient linear flow oriented straight-line analysis technique

Abstract

On the backdrop of dwindling conventional reserves, unconventional reservoirs have emerged as a pivotal chapter in resource extraction. Despite their challenges, such as low permeability, complex fluid storage, and flow mechanisms, hydraulic fracturing technology has underpinned the development of unconventional reservoirs. Consequently, this has brought about a shift in the sequence of flow regimes, e.g., the transient radial flow regime has been largely shortened by the lengthy transient linear flow regime due to the low permeability of unconventional reservoirs. Moreover, straight-line analysis (SLA), the simplest technique in rate transient analysis (RTA), is a fundamental and potent tool for swiftly extracting reservoir and hydraulic fracture information, estimating oil and gas reserves, and furnishing crucial initial data for subsequent historical matching processes. However, there is currently a dearth of review papers pertaining to a necessary guide of applying SLA in various transient linear flow (TLF) regimes and different unconventional reservoirs. Hence, this paper commences by elucidating the classification of TLF regimes, commonly used methods for recognizing flow regimes, and the diverse SLA methods used for different TLF regimes. Subsequently, it delves into a discussion of different modification techniques for variable rate/flowing pressure, gas phase, complex reservoir characteristics in unconventional reservoirs, and dynamic drainage area concepts etc. Furthermore, the application of SLA in specific domains, namely core analysis and the flowback period, is described. It culminates by surveying the advancements through an integration of novel technologies to enhance estimation accuracy. The paper also highlights certain drawbacks of current SLA technology and proposes new research directions. Ultimately, this paper would serve as an indispensable resource, offering foundational knowledge for the application of SLA in TLF to promote the production of global unconventional resources in a cost-effective and environmentally sustainable fashion in the face of a climate-resilient world.