Pushing the boundaries – deployment of innovative drilling, completion and production technology to advance a deep coal seam play

Abstract

Following technical success of vertical and deviated wells, Strike Energy audaciously continued to push the envelope while proving the commerciality of the deep coal seam play in PEL96. It was clear that extending the reservoir contact area of the wellbore and using innovative dewatering to significantly increase drainage was prudent. A horizontal well intercepting a vertical well coupled with multi-stage fracture stimulation was selected to achieve that goal. Furthermore, a new application of wide operating range electric submersible pumps would enable dewatering to much lower water rates to avoid running the pumps dry or damaging the fracture network upon gas desorption and breakthrough. Although a wellbore stability issue was encountered during the well construction phase, requiring a modified well trajectory, the horizontal well successfully intercepted the vertical well, reaching planned total measured depth. It also altered fracture stimulation approach to an indirect vertical fracture completion application, whereby fractures are initiated from the interburden layer below the coal seam. A million pounds of proppant was successfully placed in seven fracture stages. During the proppant pumping, diagnostic tools (tiltmeter and microseismic) and chemical tracers were utilised. The real-time microseismic confirmed the propagation of fracture from interburden upwards into the target coal seam. This presents the integration of well performance, subsurface information, past drilling practices and stimulation treatment results to support the decision-making process of a horizontal well construction and stimulation design as well as integration of real-time information to overcome operation difficulties and optimise well delivery. Tracer samplings and ongoing production testing during dewatering are also presented.