BP Trinidad and Tobago LLC produces gas from the Columbus Basin located off the east coast of Trinidad. Gas is produced via eleven producing platforms and daily gas production averages 2.3 bscfd. Gas produced is used to supply a domestic market and an LNG scheme. The field portfolio comprises a mix of new to mature producers producing from a deltaic environment which consists of several stacked, good quality sandstone reservoirs. The wells have been primarily designed as big-bore/high-rate completions (equipped with continuous down-hole and surface monitoring) with the aim of delivering gas to market with minimal well count.
Performance data has shown that the non-Darcy rate dependent skin is the biggest contributor to the total skin effect in these high rate wells. Early determination of the non-Darcy flow coefficient "D" enhances the ability to accurately forecast well deliverability; which is critical to both the end users and the business for proper activity planning and capital efficiency. It stands to reason that a proper understanding of same is also advantageous in predicting the performance of new producers.
Predicting the non-Darcy flow coefficient in the absence of well test data requires the value of the coefficient of inertial resistance, β; which is normally determined experimentally. This paper outlines the methodology whereby a correlation for β was developed using non-Darcy flow coefficients obtained via well tests and corrected to sand top; hence making it possible to provide an estimate of the non-Darcy flow coefficient for proposed producers. The predicted performance is then compared against actual performance for a number of cases.