As operating conditions become more severe, and the costs associated with well failure escalate, the need for effective sand control increases. However, in a time of tightening economic constraints, the need to control costs also drives decision making. In this time of apparently conflicting concerns, the industry has responded with a move away from traditional Sand Control to what can be more properly termed Sand Management.
Several projects described in the literature are concerned with a particular aspect of Sand Management. Whether it is a description of predictive modeling, preventing sand production through rate control and/or selective perforating, improved sand control through advanced completion practices of frac-pack or horizontal well gravel packing, or the latest in expandable screen products, these studies have focused on one (or perhaps two) aspects of an overall Sand Management project.
To fully grasp the benefit of this new completion paradigm, we must stop looking at well design with a preconceived answer in mind. Rather, all aspects of Sand Management must be considered when making field development decisions. It is the goal of this paper to bring the best from previous studies together to provide a solid review of available Sand Management techniques. However, since all decisions have either positive or negative consequences, this paper also reviews the economic and operational concerns associated with these decisions. An understanding of how initial decisions may impact future options will assist in enhancing our ability to optimize completion type selection.
Sand Management, the term generally brings to mind processes that must be put into place that will provide for the co-production of formation sand and reservoir fluids. However, in recent years the term has grown to mean considerably more. Sand management is now applied to all technologies, processes, and completion techniques that are meant to address the issue of producing fluids from weak formations. These technologies include computer models to predict sand production tendencies, field techniques to prevent formation failure, downhole equipment to prevent failed formation material from entering the wellbore, best practices for installing completion to maximize productivity, monitoring techniques to determine when sand is produced, surface equipment for handling produced sand, and workover equipment for performing remedial operations. From this list, it becomes very clear that many things must be considered if a truly optimized sand management plan is to be enacted for a project.
To optimize a project it must first be determined what is to be optimized. There is a tendency, when making completion design decisions to focus on either initial cost or initial productivity. While this approach provides some significant short-term benefits, it does not address the long-term goals of most producing companies. Overall the goal that is sought is to maximize the profitability of a project. It is true that a big piece of this equation will be initial cost and initial productivity; however, these are not the only parameters that must be considered. Rather, to maximize the profitability of a project, a balance must be achieved between installation cost, initial and long term productivity, operating costs, and operational risk. Time savings established during initial completion must be balanced against costs associated with future workover operations and deferred production.
When the above definition of sand management is adopted, it becomes very obvious that many papers have been written on portions of this subject area. To assist in categorizing these previous publications, the following subcategories can be offered:
Prediction: a. Theoretical sand failure models b. Techniques for rock property determinations c. Evaluation of parameters affecting formation strength over productive life of reservoir.
Prevention: a. Maximum sand-free rate determination b. Maximum allowable drawdown c. Co-production of oil and sand to maximize productivity d. Formation stabilization