Implementation of Physics-Based Hydraulic Fracturing Optimization Workflows as a Game-Changer Strategy To Unlock Tight Gas Reserves: A Deep Gas Abu Dhabi Case Study

Abstract

Abstract Increasing global demand for gas has led to a larger focus on production from deep gas HP/HT reservoirs. The case study presents an offshore field under current development with several vertical wells that confirmed varying reservoir extent, successful stimulation, and productivity. The target formation is a naturally fractured HP/HT low permeability clastic reservoir with lateral and vertical reservoir quality variations. Measured stress rotation within the structure and large minimum stress variations across different reservoir intervals support the presence of a complex stress environment where the development of a predictive 1D Mechanical Earth Model (1DMEM) becomes challenging. The combination of a variable stress dependent permeability within an altered stress field introduces uncertainty in the estimation of fracture geometry and hurdles its optimization. The paper presents a multi-frac completion strategy to be implemented in newly drilled development wells by utilizing state-of-the-art hydraulic fracturing optimization workflows driven by an integrated multidisciplinary approach. Introduction The offshore field presented here is located west of Abu Dhabi city. The subsurface structure was first identified in 1966 and is part of a regional N-S extending structural trend with other nearby fields. The targeted formation is a deep naturally fractured tight gas clastic reservoir that presents lateral and vertical reservoir quality variations. It possesses three different reservoir units (A, B and C) with diverse petrophysical and mechanical properties. The new development considers cased and cemented s-shaped wells with a dedicated 4 ½” frac string to pump stimulation treatments at high rates. The “plug and perf” completion methodology was selected since this allows flexibility given the initial uncertainty in the hydraulic fracture growth and to properly evaluate intervals production performance.