Microfracs and Frac Diagnostic in Tight Gas Reservoirs; Continuous Surveillance to Update Frac Design

Abstract

Abstract Barik Sandstone is a well know condensate reservoir developed in several fields across Central Oman between Ghaba Salt Basin and Fahud Salt Basin. Its particularity lays in the vertical and lateral heterogeneity resulting from the fluvial-deltaic depositional environment and an associated quite unusually high stress differential across the different mudstone and sandstone members. Barik is classified as Unconventional Tight Gas due to the low average permeability and requires hydraulic fracturing (HF) to economically exploit the natural resources. Understanding the reservoir parameters was a key success for successful stimulation of the Barik Sandstone in Khazzan and Ghazeer Fields in Oman. A massive surveillance campaign was carried out to understand the reservoir properties including detailed seismic and long-term flowing and build up data. building a calibrated Mechanical Earth Model MEM allowed the team to design the best fit frac design that made the successful results on frac placement and well performance. With the extension of the reservoir height, more data were used to update the Mechanical Earth Model that helped to refine the frac design. this paper describes the workflow of how additional data helped modifying frac design using DFIT injections & different frac design approaches across different barriers. The Mechanical Earth Model created at the early stage of the field development was generated using a detailed Microfracs stress test and reservoir properties using static and dynamic data. layers stresses confirmed using several frac injection to test the break down pressure of that layer which then helped into defining the best frac design for the reservoir. The successful stimulation treatments confirm the value of such detailed surveillance and details workflow that was continuously updated using frac injections. This has a major impact on frac performance and field development plan that reflect the outstanding performance of these wells.