SPIDR System FAQs

The SPIDR is calibrated to a full scale pressure of 15,000 PSIA.

The SPIDR's internal quartz transducer has a resolution of 0.01 PSI and an accuracy of < 0.01% of full scale.

The exact number of samples that can be stored depend on the programming configuration and whether any external transducers are being used.

The SPIDR is powered by three "D" cells that can power the SPIDR for 1,500,000 samples or 2 years.

No. Every time the SPIDR takes a measurement it checks the battery voltage. If the voltage drops to an unacceptable level, the system will shut down and use the remaining battery voltage to preserve stored data.

No. There are safeguards in place within the SPIDR that will preserve the memory contents for several years.

The battery voltage can be monitored using our free software without interrupting sampling.

No, you can communicate with the SPIDR and download the memory contents without any interruption to your test.

Each sample the SPIDR makes includes: date, time, sample number, pressure from the internal transducer, and readings from the external transducers (if present).

Yes, the sample rate is programmable and the interval can be varied from a tenth of a second to hours or days! The sample rate can not be changed after the SPIDR has been programmed.

The SPIDR is extremely compact and measures just 5 3/4in. x 5 3/4 in. x 9 in. and weighs just 8lbs.

The SPIDR has been certified by ATEX and is CSA certified Intrinsically Safe.? The SPIDR is also suitable for sour gas service.

After downloading the SPIDR the data is imported into our proprietary report generating software CSPRG. Using a modified Cullender-Smith routine the data is converted to bottom hole pressure. This optimized routine has been proven in thousands of tests. It accounts for the quantity and properties of produced fluids, divides the tubing into discrete elements with a unique 'Z' factor for each and computes a theoretical temperature profile based on well depth and well head and bottom hole temperatures. The software also uses different friction loss models for increasing flow rates and incorporates a thermal decay option to compensate for cooling of the gas column when flowing well head temperatures exceed 120 F.

Yes, you can, if:

1. Your well is flowing above the critical unloading velocity with no slugging in the wellbore (Click here to calculate minimum flow rate required to prevent liquid slugging).


2. You acquire and process the wellhead pressure data using a SPIDR pressure-transient test kit and associated report generating software from Data Retrieval Corporation.




The SPIDR (Self-Powered Intelligent Data Retriever) automatically measures wellhead pressure, adjusting its data storage rate to the rate of pressure change. The 9-lb unit will operate up to 2 years unattended, storing up to 5,000,000 date/time-coded readings. It can also monitor a second and third variable, such as flow, pressure, or temperature.

Cullender-Smith, optimized

The 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.

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 world

The 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.