![]() Flow efficiency for a given set of perforations is affected by charge size and design, formation rock and fluid properties and by under- or over-balanced conditions during perforating. Well tests and their interpretation are also affected by perforation depth and flow efficiency. Even in stimulated wells, good perforation flow is needed to allow fracturing or acidizing fluids to enter the formation. We provide revised formulae for averagepermeabilities to be used in analytic calculation of ideal flow rates.įlow efficiency of perforations plays a major role in determining well productivity in naturally-completed production or injection wells. As previously noted, average-permeability formula provided by API do underestimate ideal flow, but to a much lesser extent than previously stated. We confirmthat non-Darcy effects are generally negligible for steady-state liquid flows. ![]() We investigate the effects of non-Darcy flow arid anisotropy on ideal flow. We find that CPE for the older tests tend to lie between 0.8 and 1.0 for a wide range of damaged zone characteristics, while the newer test using radial boundary conditions, is much more sensitive to damaged zone characteristics. CPE values are related to thickness and permeability of the damaged zone and to skin values. We also provide curves for interpreting the older style tests in arbitrary sample diameters. Using numerical analysis, we provide curves for relating core flow efficiency (CPE) values from older 4th edition tests with those from the new test. ![]() In this paper, we review these procedures and develop the basic equations used to interpret the results. The recently revised API (American Petroleum Institute) Recommended Procedures for Evaluating Shaped-charge Perforators (RP43, 5th ed.) includes test procedures for measuring perforation flow performance under simulated in situ conditions.
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