Conventional Tight Gas Field Through Unconventional Eyes: Data Analytics Help to Optimize Fracture Design and Operations

Abstract

Deep tight gas fields in Northern Oman are often compared to and approached with unconventionals due to their tight matrix properties and the necessity of employing hydraulic fracturing to deliver productivity. Complicated by operational constraints and field histories, hydraulic fracture effectiveness – how fracture stimulation delivers relative to how much matrix flow contributes to production – remains a puzzle and a challenge. This further affects how to optimize existing completion and stimulation strategy in order to improve the value proposition. In this study, we review the fracture and production performance of a mature gas field in Northern Oman. Integrating data of various technical disciplines, we re-examine a wealth of cumulative field data over two decades of operations with an aim to identify the key enablers for fracture placement and production. With integration of reservoir properties, geomechanics, and time-lapse production profiles, we identify that geomechanics plays a key role in controlling reservoir fraccability and the placement of hydraulic fractures. While hydraulic fracture containment within the Barik formation has been well recognized and considered a given in multi-staged fractured vertical wells, the creation of fracture heights is found dependent on the in-situ stress conditions and pumping metrics, which further links to productivity. Such inter-relationship could potentially be utilized to optimize fracture performance by a refined placement strategy. With big data, the common technical opinions that normally arise from a deterministic approach on limited data can be better visualized and addressed. The statistical strength of the analysis leads to improved understanding of the subsurface complexity, interaction of reservoir quality with completion design, and a suite of future optimization opportunities.