Understanding the Effects of Reservoir Changes in Sand-Control Completion Performance

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSand-control completion performance has been a key point of discussion within our industry for several years. Widely varying values of skin and PI exist and arguments have been made to oppose or support different completion techniques currently available. In many cases, these arguments are made in attempts to promote certain completion techniques when more time should be spent understanding the probable sources of the condition. This paper examines closely (1) how reservoir properties in the near-wellbore region can change significantly over time under production conditions, and (2) how these changes can affect well performance over time. It looks at the significance that reservoir compaction can have when reduction in permeability is accounted for and how detrimental this compaction can be to well productivity.In reservoirs subject to compaction, the behaviors of radial completions are compared to frac-pack completions over the life of the well. The paper demonstrates that although the conductive fracture may not be a dominant factor in well productivity early in the life of the well, it can become very significant in maintaining well productivity and performance later in the life of the well. In effect, these completions can be designed to improve well performance over time, and in many cases can result in decreasing skin factors with time, thus minimizing the decline in productivity.Reservoir modeling was performed that considered nearwellbore compaction and the presence of a high-conductivity fracture; this model agreed well with observations made from several deepwater developments.A detailed case history is also presented wherein sufficient reservoir evaluation was conducted over time to validate the effects of compaction and the long-term performance improvements that can be achieved using frac-pack completions with these reservoir conditions.