The electronic Permanent Downhole Gauges (PDHG) has traditionally been used in the Karachaganak field to monitor downhole pressures and temperatures, for reservoir management. The overall performance and quality of the data from some of the Permanent Downhole Gauges (PDHG) installed in the Karachaganak field was not satisfactory. Hence, fibre optics has been investigated as an alternative technology due to the reliability, calibration and cost concerns related directly to the Permanent Downhole Gauges (PDHG).
This paper will discuss the implementation and installation of the first fibre optic pressure and temperature monitoring system installed in the Karachaganak field.
A dual fibre optic pressure and temperature system (rated to 200°C and 20Kpsi) was installed to a depth of approximately 5000m with a maximum inclination of about 35°. The metallurgy for the fibre optics system was Inconel 718 due to the presence of H2S. The surface equipment comprised of a Zone 2 rated Wellhead Data Acquisition Unit which has direct connection to the operation base providing ‘real time’ pressure and temperature updates (up to one second update rate).
The paper will highlight some of the design and implementation considerations that were addressed to combat issues which had been experienced with more conventional monitoring systems such as reliability, accuracy and data communication issues. It will also describe the process that was undertaken to meet the stringent Kazakhstan Metrology requirements that are required to be obtained prior to the deployment of a subsurface measurement system. This process involved meeting the requirements for GOST-K for Safety and Quality and the Metrological Certificate which ensures that all measuring instruments are of stated accuracy and resolution and are acceptable to an accredited Institute of Metrology.
It will discuss the detailed Factory Acceptance Tests (FAT) and System Integration Tests (SIT), as part of the critical planning process prior to the field installation.
The paper will also cover the challenges during installation and subsequent use. The deployment data interface requirements and associated benefits during well stimulation, well testing and subsequent production will be described in full.