In highly fractured reservoirs, where gravity dominated recovery processes are employed, fluid contact measurements and isobaric mapping are useful tools for understanding operational and process changes. Monitoring fluid contacts accurately in highly fractured reservoirs has always posed a challenge due to limitations in the measurement tools. Gradiomanometer surveys and electronic fluid property surveys lack the depth resolution needed to locate contacts, and direct measurement methods are time consuming, messy and yield no secondary information for quality control. Fluid gradient measurement is the desired method; but historically, limitations in gauge precision or thermal response have made this method unattractive.

An electronic pressure gauge using a silicon crystal sensor was shown to provide predictable response to strain under changing temperature and to provide the precision and accuracy needed for repeatable contact measurements and reliable pressure mapping. The pure silicon crystal has a small mass, a thin unbonded structure, and a temperature sensor for compensation placed in close proximity thereby decreasing the stabilization time required for true pressure recording. Rapid pressure measurement allows shorter, more frequent gradient stops; and consequently better data resolution for contact calculations.

Replacing non-pressure based contact measurement techniques in a field where bottom hole pressure surveys were taken on staggered intervals saved real dollars. This was done by adding one to two days onto a pressure survey and eliminating the separate contact survey. Measuring both contacts and pressures concurrently reduced time-normalization problems and increased data confidence. Accurate, repeatable pressure measurements clarified details of operational changes on the reservoir management process, improved the data collection process, and reduced expenses to the operator.

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