Paradigm Shift: Pad Optimisation for a Potential Tight-Gas Development in Russia

Abstract

As the extensive Russian gas business matures from developing the high-permeability (Cenomanian) formations, into lower-permeability (Turonian) gas deposits, a number of economic challenges will need to be addressed in order to remain effective. The number of wells, pads and associated infra-structure and expenditure in a tight-gas environment will dramatically increase, challenging the economic outcome and environmental impact of using the established approaches. In order to achieve the maximum return, it is imperative that the established pad and well, construction and execution processes, are challenged, re-considered and subsequently optimised for the new reality. This paper will describe a worked example of such reconsideration for a potential tight-gas development in Western Siberia. Well pad construction for Oil and Gas developments in Western Siberia is well established, so very well practiced in fact that often little is changed between one development to the next, and the reservoir and well requirements are only considered through a regulatory lens. However, as the development economics become more challenging in the lower permeability environments, much more optimisation will be required in order to maximise the efficiency. The approach taken here is to start with consideration of the traditional pad design, as was implemented for three pads built during an earlier Turonian Appraisal phase; and then incrementally consider areas of optimisation until the most cost-effective and solely requisite pad design has been achieved. Instead of outsourcing pad design to a disconnected/remote third-party engineering service, hand-cuffed by decades old established practice, the approach taken was to internally create an integrated view on pad functionality, technical requirements and optionality for a successful development. The results of this approach speak for themselves, with areal percentage reductions readily achieving a level of 50%, with an obvious associated cost improvement. Additionally, the flexibility and optionality that can be built into incremental pad design/construction offer new insight into what can be achieved in these very challenging environments. As developments move into more challenging rock quality, the previous approach of delineating and carpet-bombing a field with wells and pads becomes less effective and highly impactful on the overall development economics. Almost all Global tight-rock developments are phased, in multiple stages, based on improving sub-surface, productivity and well-design knowledge incrementally. Additionally, the inherent ability, via this method, to minimise the environmental footprint cannot be overstated. Techniques that will be presented show how a holistic approach will result in the most effective use of limited resources and a reduction of the impact of the surface footprint. The novelty of this approach is that it challenges what has become, over decades, the rigid and inflexible approach for pad construction that is linked with a higher-permeability field development era. It offers a new and refreshing insight into what may be achieved when an integrated and internal approach is taken to such considerations, while remaining cost effective, fully compliant and flexible.