![]() ![]() This obviously will solve the sand production problem but will also increase costs and may reduce well productivity. If there is uncertainty, the conservative approach is to always apply sand-control completions. ![]() At that point, the decision normally ceases to be primarily a technical issue but more of an economic and risk management exercise. The difficulty arises when the strength of the formation material is marginal. Making the decision whether to gravel pack is fairly easy if the formation material is either hard (no sand production) or weak (sand production). Therefore, gravel packing cannot be applied indiscriminately when the possibility for sand production from a well is unknown. The decision is complicated by the fact that sand-control techniques, such as gravel packing, are expensive and can restrict well productivity if not performed properly. Here, the consequences and risks associated with sand production are significantly different because of differing costs and risks associated with remedial well operations hence, the decision to use a sand-control technique is both an economic and operational decision that must be made with limited data. One example might be a subsea project, as opposed to a land development project. Even if the reservoir and formation properties are almost identical to other developments, the operating conditions and risks may be such that different strategies apply. The difficulty of determining whether sand control is required in a given well is compounded when the well is drilled in a remote area where there is no producing experience and where the various reservoir factors are slightly different from previously exploited regions. However, initial good results may prove misleading, as reservoir and flow conditions change. The prediction required is on a reservoir-by-reservoir basis. Normally, it is not necessary to predict sand production on a well-by-well basis because wells in the same reservoir tend to behave similarly. Until better prediction techniques are available, the best way of determining the need for sand control in a particular well is to perform an extended production test with a conventional completion and observe whether sand production occurs. Predicting whether a formation will or will not produce sand is not an exact science, and more refinement is needed. In some geographic regions, guidelines and rules of thumb apply that have little validity in other areas of the world. There are a number of analytical techniques and guidelines to assist in determining if sand control is necessary, but no technique has proven to be universally acceptable or completely accurate. Predicting whether a well will produce fluids without producing sand has been the goal of many completion engineers and research projects. ![]()
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