ABSTRACT

Hydraulic fracturing technique has been proven as an efficient method to enhance productivity of onshore resources including shale oil and gas, and for in-situ recovery mining systems, and to increase the safety and efficiency of block cave and longwall mining. Local variations in in-situ stresses, rock material, layering, or existence of natural fractures can affect the direction of hydraulic fractures. Alternatively, a new technology based on Radial Jet Drilling (RJD) has been widely used in petroleum and geothermal industries for improving injectivity/productivity of wells, where small-diameter holes are drilled out from the wellbore into the rock formation using a high-pressure fluid jet. In this study, we investigate a directional hydraulic fracturing technique by combining the RJD technology with hydraulic fracturing technique to optimize the hydraulic fractures. In the proposed method, RJD laterals, drilled in a desirable depth and direction in the host formation, are hydraulic fractured. The hydraulic fractures are propagating along the RJD laterals.

1. INTRODUCTION

Development and improvement of unconventional drilling and completion techniques has substantially increased production of unconventional reservoirs around the world. Hydraulic fracturing technique has proven as an efficient method to enhance productivity of unconventional resources including shale oil and gas (Economides and Nolte 2000), geothermal reservoirs (Salimzadeh, Grandahl, et al. 2019), and for in-situ recovery mining systems, and to increase the safety and efficiency of block cave and longwall mining (Jeffrey and Mills 2000).

Hydraulic fracturing is a process in which a pressurized fluid is injected into rock to cause fracture initiation and propagation. A hydraulic fracture initiates from the wellbore and is expected to grow along the minimum in-situ stress plane. Other factors including layering, stress contrast, weak bedding planes, natural fractures, and anisotropy may affect the direction of the hydraulic fracture. Thus, other than the initiation point in the wellbore, the operator has little control on the direction of induced fracture, arising the need for methods to control the direction of hydraulic fractures.

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