Methodologies and Tools for Coalbed Methane (CBM) Field Development Planning Studies

Abstract

Resource plays such as Coalbed Methane (also called Coal Seam Gas) fields typically exhibit a number of unique characteristics that set them apart to other hydrocarbon accumulations. We will argue in this paper that as consequence, conducting effective field development planning studies for CBM resources requires adopting a markedly different approach to the ones typically followed with conventional oil and gas fields. In contrast to traditional offshore plays, replete with a rich literature of best practices and adequate tools, coalbed methane field development planning typically involves very large areas and number of wells, hence a correlative abundance of (static and dynamic) data, but also displays an often surprising variability between neighbouring wells. This variability is the consequence of a high degree of heterogeneity present at a small (1's-10's metres) to medium (10's-100's meters) scale, notably for permeability, but also isothermal properties, gas content, and even net coal distribution and seam geometry for some plays. This paper offers insights on integrated development planning methods, uncertainty management techniques and modelling workflows, accumulated through the experience of a number of CBM plays. Expected relationships and possible crossparameter models for the key reservoir properties are discussed. The development of practical tools to characterise the reservoir properties, as well as the performance of different well and completion configurations, simulation, field development planning, all the way to ultimately assessing the economic potential of the play are also illustrated.