Sanding Study for Deepwater Indonesia Development Wells: A Case History of Prediction and Production

Abstract

A detailed sand prediction has been made for three wells at Chevron's West Seno field based on logs/lab data and the results have been calibrated with production data. Both maximum allowable drawdown and depletion increase with depth. Additionally, oriented perforations offer an improvement to perforation stability against sanding: the maximum allowable drawdowns and depletions are increased for all sands. Finally, an analysis is presented on the economics and trade-offs of vertically-oriented perforating (with possibly managed sand production) versus frac-packing. Sand onset prediction agrees fairly well with the observed drawdown/depletion for horizontal perforations. This benchmarking appears to support the validity of the shear-failure model. This is important because the model, while fairly simple, has many different inputs, including depth profiles for unconfined compressive strength (UCS) and in-situ stresses, which involve sophisticated prediction techniques themselves. Continuous sand rates (for oil wells) have also been predicted by extending the shear-failure sanding model. As depletion increases over time, added perforation intervals begin to fail/collapse, increasing the sand rate. There are periods of agreement and underestimation (by a factor of ~4) between observation and prediction. This is important because it is the first time this model has been benchmarked against observation at early times in a well's life. It appears the model can provide a first estimate of sanding levels in oil wells, which are useful to assist the design of well facilities for dealing with sand. Finally, a sand prediction was used to evaluate oriented perforating in lieu of frac-packed completions. The evaluation defined production scenarios, by building nodal and production forecast models, and ran incremental economics. It indicated that oriented perforating can provide favorable economics over fracpacks if critical rock properties and production plans are defined and understood.