Chapter 7 - Field development of tight unconventional reservoirs

Abstract

A real challenge facing tight unconventional reservoir production and development is the requirement of high oil prices, low development costs, or preferably both. This adds a problem to the combining challenges of producing from complex and tight formations. Nevertheless, considering the challenges of development, tight unconventional reservoirs are expected to provide a substantial proportion of global energy over the coming decades. While it is a very expensive practice, horizontal wells can be used as the main resort for reaching out to the locked tight formations and maximizing reservoir exposure. Horizontal drilling technology improves production, enhances the effectiveness of sweeping, and provides access to tremendous quantities of unconventional reserves. Although in many developed tight unconventional reservoirs, horizontal wells demonstrated a fair increase in production output, in some other situations, productivity was not economically viable. Furthermore, issues of fracture closure and lack of understanding of reservoir fracture geometry pose more challenges to developing tight unconventional reservoirs, in addition to the rapid decline in productivity from the drilled wells (the L-shape profile). These challenges form the future of tight unconventional reservoirs and probably will make R&D active for many years to come. Recently, the advancement of drilling technologies using multilateral well drilling, more efficient hydraulic fracturing, and slim wells presents much hope for cost-effective development. Refracturing of horizontal wells and selecting more realistic well spacing give more optimism for a better future in this industry. Another aspiration is the fast-growing unconventional enhanced oil recovery. Thus, unconventional enhanced oil recovery brings another futuristic development venue for tight unconventional reservoirs production growth, taking advantage of the many abandoned horizontal wells around the globe that still carry up to 90% of residual oil saturation.