Testimonials
As a 15+ year user of DRC's SPIDR gauge, I can attest to its utility. The SPIDR has given the operator a low-cost alternative to downhole gauges, especially when running an extended well test or back-to-back tests on ...
- Ralph R. Roesler
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WHP to BHP
Can DRC accurately convert surface pressure to downhole pressure?
Yes we can! We can convert either flowing or static pressures using a proprietary modification of the Cullender-Smith routine. This routine accounts for the produced fluids, divides the tubing into discrete elements, each with a unique "Z" factor, computes a temperature profile based on well depth and temperatures, uses friction loss models for increasing flow rates, and compensates for the cooling of the gas column when the flowing wellhead temperature exceeds 120 F.
Cullender-Smith, optimizedThe key to the accuracy of test data provided by the SPIDR system is a proprietary modification of the Cullender-Smith routine for converting wellhead pressures to bottom-hole pressures. To optimize the Cullender-Smith routine so that it accurately models a broader range of gas wells, Data Retrieval Corporation has made several important modifications:
- The quantity and properties of produced fluids are accounted for.
- The tubing is divided into discrete elements, with a unique "Z" factor for each.
- A theoretical temperature profile is computed for the well bore, based on well depth and wellhead and bottom-hole temperatures.
- Different friction loss models are used for increasing flow rates.
- A thermal-decay option compensates for cooling of the gas column on wells with flowing wellhead temperatures above 120F.
Using the optimized routine, Data Retrieval's report generating software converts wellhead pressures to bottom-hole pressures with exceptional accuracy, as long as the well meets the criteria given at the beginning of this ad. If there might be a liquid column in the bore, but the other criteria are met, you can still test the well by running a two-rate test instead of a build-up test (call for details). Built-in subroutines calculate all the information you need for plotting and analysis. You get plots, print-outs, and an ASCII file of bottom-hole pressures, pseudo pressures, delta time and pressure, cumulative production, elapsed time, Horner time, rates, and more -- everything you need for comprehensive reservoir analysis.
Proven accurate on thousands of wells around the worldThe SPIDR system has been used in major gas fields throughout the world, and it has always delivered well analysis data equal to or superior to that provided by conventional downhole testing. This has been confirmed by using the SPIDR system in parallel with downhole gauges on hundreds of wells.
Want more proof? Try it for yourself.The SPIDR pressure-transient test kit is available for rental or purchase. Call today to arrange a test or for additional technical information, case histories, and descriptions of other applications.
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