Non-Darcy skin is always present in the gas, gas-condensate, and high Gas Oil Ratio (GOR) oil wells, increasing as the rate increases. However, the reverse is true in a well with a loading skin. This paper outlines the interpretation procedure and unmasking of the non-Darcy skin in a loading well with a new calculation approach.

A rate test for a gas or gas-condensate well with a pressure transient test (PTT) is required for well-test interpretation, and the diagnostic and the matched well production history plot provide the nominal or rate-dependent skin. The effective skin comprises completion, non-Darcy, and loading skins in a well with decreasing effective and loading skins. This approach focuses on matching the production history plot to provide the rate-dependent skins to determine the loading and completion skins.

It becomes impossible to determine reservoir parameters with a masked radial flow regime. When compounded with serious liquid-loading skin, non-Darcy skin determination becomes another challenge. In this scenario, Ramey's method and Spivey's for determining non-Darcy skin become insufficient because the former deals with an increasing non-Darcy skin only; in this case, we have a decreasing skin, and the latter does not account for a loading skin. This study resolves the limitation of both methods by accounting for the loading skin and unmasking the non-Darcy skin. With the new formulation for effective skin, the reservoir parameters can be determined from the general flow regime equations. The loading-skin rate-mitigation strategy proves successful in well recovery.

This approach is utilized with a loading-skin mitigating rate to recover well that would have quit on production. The non-Darcy skin effect and the loading-skin curves reveal a minimum loading-skin mitigating rate for improved productivity and overcoming Ramey and Spivey methods’ limitations.

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