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Content archived on 2022-12-27

PERMANENT DOWNHOLE PRESSURE MONITORING OF HYDROCARBON FIELDS

Objective

To develop a more reliable 100% European based Permanent Gauge system to monitor downhole pressure in hydrocarbon producing fields. This information is vital to evaluate and manage oil and gas reservoirs; however, today these permanent gauges are unreliable.
This new permanent downhole pressure gauge system is based on an innovative sapphire crystal transducer developed and owned by the company. The gauge's electronics will be built using European components in special downhole circuits already developed within the company. To better suit the oil field requirements, the complete gauge will be implemented as a smaller diameter sonde. The trouble-prone interconnections between the downhole and the surface will be made more reliable using new metal-to-metal seal designs. Finally, a new stand-alone surface acquisition box will provide a standard PC computer compatible user interface and interconnection to standard C.C.I.T.T. telecommunications.
Two permanent Sapphire Gauges were built and tested by engineering. One of the permanent gauges was successfully field tested for 32 days down in a well at the limit of its 150 deg. C specification, the other gauge is now installed in a P/T test cell to continue its life testing at the companies' expense. Failure of electrical connections is the key problem encountered with these "permanent" installations that must operate downhole for a minimum of five years. This has been solved in three ways : first the connections have been eliminated, where ever possible. For example, the critical connection between the gauges's cable head and its cable are now directly welded. Second, when mechanical connections must be made, metal-to-metal seals are employed instead of the older rubber O-ring seals that can leak with time. Third, the gauge itself has been hermetically sealed by welding it closed. This eliminates two failure prone mechanical seals and it ensures that the gauge's electronicsare in a well controlled environment, free of gases and fluids that could, in time, diffuse through O-ring seals.
- Two additional Permanent Sapphire Gauges were built by our Manufacturing department in accord with the engineering design file.
- A surface data acquisition box, called the Autonomous Surface Unit (ASU), was built and used to support the testing of these permanent gauges. This box is being commercialized.
- Schlumberger invested in two additional laboratory facilities that complement this Thermie project: A Sensor long life test facility was built and is running 11 pilot series Sapphire sensors. So far, four months of testing have been made at 150 deg. C and 15 kpsi. Another facility, called a P/T test cell, was installed to life test complete gauges at downhole conditions.
- A 10 kpsi version of the sapphire sensor design was analyzed mathematically. The results showed that the stability and sensitivity could be significantly improved. Test samples were built and lab tests confirmed these analyses. As a result of this success, the pilot series production of these 10 kpsi sensors has been launched.
- Commercialization efforts with clients were initiated, tanks to the Thermie invitation for us to participate in their booth at the Offshore Europe 93 exhibition in Aberdeen Scotland.
This project focuses on the design, integration and testing of the three key aspects of a permanent gauge installation; the downhole pressure gauge; its interconnections to the surface, and, the surface interface with the user. The heart of the new downhole gauge is a new high performance sapphire crystal pressure transducer. The sapphire crystal design provides a very stable and rugged substrate material that overcomes the drift errors that inherent in the metal strain gauges that are used today. An Analog-to-Digital Converter will be adapted to the new pressure transducer's output characteristics. Then a digital interface will transmit the pressure and temperature measurements to the surface. To install the complete gauge in permanent downhole installations, the transducer and its asociated electronics will be built into a smaller (32 mm) diameter sonde that will withstand the harsh downhole environment (i.e. 150 deg. C and 15000 psi).
Today, over 50% of the failures with Permanent Gauge installations can be traced to connection problems between the downhole equipment and the surface acquisition system. This project will make significant reliability improvements by using new metal seal technologies. Extensive qualification tests will be performed in the laboratory to qualify these new metal seal designs to the required downhole conditions.
A new surface acquisition box will be made that can provide power to several gauges, record their measurement data and communicate with remote users. To conform to European offshore oil field requirements, this surface equipment must be made explosion proof for class 1 operations on the rig. It will be able to operate unattended for long periods of time and it will be compatible with standard PC computers and telecommunication systems so users can easily obtain the vital reservoir measurements and work with the data.
A prototype of this system will be built and tested in the laboratory to verify that it meets its stringent operational and metrological specifications. Finally, the equipment will be prepared for field testing in real conditions.
The equipment will be installed in an appropriate and representative field location to assess its overall performance. The operation will be closely monitored and corrective actions taken, if needed. All the field test results will be analyzed and a complete manufacturing file will be prepared. Refinements may be made to improve the product's quality, reliability and performance as well as to improve manufacturing efficiency and reduce costs.

Call for proposal

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Coordinator

Schlumberger
EU contribution
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Address
26 rue de la Cavée
92140 Clamart
France

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Total cost
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