Abstract

Natural fractures can reactivate upon stimulation and interact with propagating hydraulic fractures. This interaction usually creates complex, productive fracture networks that can remain open during production. Geomechanical models quantify key parameters that control the extent and characteristics of the conductive reservoir area in naturally fractured reservoirs. The models can be utilized to optimize stimulation design parameters for infill wells or re-fracturing operations. In this paper we present stimulation design optimization within the framework of a coupled "Geomechanics-Microseismic-Reservoir-Discrete Fracture Network (DFN)" workflow. A series of simulations are conducted to understand key parameters that control the conductive reservoir area of a planned infill well. In these simulations both stimulation design parameters (e.g. pumping rate) and well architecture (e.g. stage number, well orientation) are varied as their impact on conductive reservoir area is quantified. Results show that extent of conductive reservoir area in a naturally fractured reservoir can be controlled. The workflow introduced in this paper can guide field operations and optimize stimulation design to (i) maximize conductive reservoir area of an infill well (ii) and limit/control fracture communication between infill wells and existing producers.

1. INTRODUCTION

Hydraulic fracture (HF) characteristics and geometry are a complex function of in-situ stress state, stress shadowing, formation anisotropy, rate and pressure dependent rock mechanical properties, wellbore orientation, and the natural fracture networks [1-5]. In particular, the presence of natural fractures and their interaction with propagating hydraulic fractures can dictate the resulting fracture network patterns and the extent of conductive reservoir area [3-7].

In naturally fractured reservoirs, this interaction can create complex fracture network geometries as observed from Microseismic (MS) data [4, 8-10]. However, in most commercial hydraulic fracturing simulators, fracture path is predefined and planar (Fig. 1). This is an oversimplification of the real processes (in particular for horizontal wells), in which multiple hydraulic fractures can interact with each other and/or with the pre-existing natural fracture network to follow non-planar and complex paths.

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