Effective sand control is extremely important for production of hydrocarbons from shallow unconsolidated sand reservoir. In absence of any sand control measure installed in the well, there is high risk of Sand production along with the hydrocarbons. Sand production may result in damage of X-Mass tree and/or Sub-sea infrastructure components. In extreme cases, when the sand production goes beyond the critical limit, it may lead to a situation when the field production has to be stopped. In view of this, in Deep water environment, sand production is considered as a potential hazard. It may lead to tremendous impact on reservoir economics and sustained production from the field.

The commonly used sand control technique is to install suitable sand screens and a packing of gravel at the sand face to restrict the movement of sand particles from the reservoir to the borehole. Gravel packing can be achieved through open hole gravel pack, cased hole frac pack or simply by lowering a pre-pack perforated liner/screen. Once the gravel packing is done, it is required to know the competency of the pack to confirm its effectiveness. Gravel pack evaluation is basically done from the data acquired by a logging tool conveyed either through wireline or wash pipe below the Gravel pack assembly run on the work string.

The techniques described in the paper were applied in deepwater gas reservoir consisting of thick unconsolidated sand and thin bedded sand- shale sequences. Wireline logging was done to evaluate the pack efficiency. In the absence of a single tailor made tool or technology, four different tools were used for this purpose with various advantages and limitations. Pipe conveyed memory logging device was also used for gravel pack evaluation in few cases. The results of all the methods were analyzed and an attempt was made to find a suitable cost effective technology for the evaluation of gravel pack. No Gravel pack evaluation job was included in the initial development plan by the operator, however as the operations progressed it was found to be essential especially in Deep water environment.

This paper describes the experience of the operator with different gravel pack evaluation methods and highlights associated merits and demerits. It also describes some specific cases where gravel pack evaluation became crucial for decision making and saved the production well.

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