Tailored Workflow for Optimizing the Hydraulic Fracturing in Tight Reservoir Development: A Case Study from Cambay Basin

Abstract

Rock fabric characteristics of Gamij Field lies in the purview of conventional reservoirs but are as complex and uncertain as unconventional. It is a multi-layered, heterogeneous reservoir on depletion drive with very low permeability. Even after hydraulic fracturing and artificial lift, the production rate lies in the range of 3-4 m3/d. This paper evaluates the impact of past hydraulic fracture operations and uses this understanding to optimize the stimulation strategy for future wells. A customized multidisciplinary modeling and flow simulation workflow; integrating petrophysical, geomechanical, stimulation and production data was adopted and applied to sectors of the field. Two techniques were combined 1. Unconventional (Fast Loop) 2. Conventional (Slow Loop) in an intriguing and iterative manner. Hydraulic Fractures were designed, optimized and calibrated using a rigorous workflow of unstructured grid and unconventional fracture modelling/3D planar fractures in the sector models. Sector model is considered the most effective approach to characterize completion quality in Gamij Field due to the limitation of current modelling technologies to design and simulate hydraulic fractures in full-field model. The results of sector model is validated with full field model and a number of iterations were performed to match pressure from the result to the initially assumed in creation of 3D MEM (Mechanical Earth Model). Reservoir quality (RQ) estimation is affected by complex mineralogy including abundance of iron and titanium rich sediments. Stress regime shows vertical transverse isotropy nature of shales and suggest re-orientations near to fault zones. There are several areas, especially in the eastern part, where the tectonic regime changes from normal to strike-slip faulting. HF modelling not only explains the contrasting behavior of existing wells, but also discusses alternatives that could help to unlock the true potential of the pay zones. This paper elucidates techniques to maximize reservoir understanding and allow optimization of hydraulic fracture design in terms of casing diameter, job size, and design. Simulations shows multiple fractures were created from different preformation cluster in a single stage treatment. Overall, the case study showcases different factors that govern the development of a tight oil reservoir and the ways to characterize and quantify these uncertainties. This work is the first step to quantify the complex reservoir mineralogy, impact of laminations, depletion, stress variation on the efficiency of HF jobs. Identification of potential sweet spots based on reservoir quality and completion quality indexes, establishing well productivity. The uncertainty cannot be eliminated but it ought to be reduced and risk analyzed before the actual execution.