Engineering Visual Presentation E06: Tight radius drilling in coal, a re-emerging technology

Abstract

Engineering Visual Presentation E06

Tight radius drilling (TRD) technology presents a novel drilling technique to enhance productivity from shallow coal seams, particularly at depths where drainage from surface-to-inseam (SIS) wells is limited and hydraulic fractures propagate horizontally. The technology works by boring multiple horizontal laterals at varying angles into the coal seam perpendicular to the originating vertical well bore. The laterals propagate using a flexible hose and hydraulic jetting nozzle, and lateral progress is measured using the wired transmission. TRD can be deployed in mining or coal seam gas (CSG) environments, particularly in low-permeability, highly compartmentalised coals. Historically, TRD laterals in mining applications have penetrated up to 200 m and total lengths of ~1400 m from a single coal wellbore. This study reports historical measured results of created lateral lengths in two past successful applications, illustrating TRD’s benefits for mining applications in the Bowen Basin. These findings indicate that TRD could complement SIS technologies for CSG applications and compete with SIS wells in shallow, compartmentalised or low-permeability CSG reservoirs where increased surface area and broader areal extent are necessary to achieve a commercial rate.

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