The first time in China｜Permanent fibre optic monitoring technology outside the casing is successfully applied to the Yingpai 3H platform.

Recently, good news came out from Yingpai 3H platform of Oil Production No.3 Plant Ganchaigou, that permanent optical fibre monitoring technology outside the casing was successfully applied to 3H14-3 and 3H15-4 wells of Yingpai 3H platform. This is the first time in China to carry out permanent optical fibre monitoring outside the casing in two wells on the platform at the same time, which plays a key role in guaranteeing the effect of fracturing and reforming on site.

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The permanent fibre-optic monitoring technology outside the casing can clearly record the downhole operation and provide a more complete understanding of the downhole and formation conditions, thus improving the accuracy of the interpretation to the maximum extent. The technician told the reporter that during the fracturing process, the field personnel used the permanent optical fibre monitoring technology outside the casing to monitor the sand feeding of the perforation clusters in real time, and to dynamically analyse the amount of sand feeding of each perforation cluster. At the same time, the use of optical fibre to determine whether the injection is successful or not, the sealing effect of the bridge plug, the steering effect of temporary plugging, as well as real-time guidance for the optimization parameters of the project have an inherent advantage.

Cui Ronglong, Technical Center of Oil Production Plant No. 3, said, ‘This is the first time that the oilfield adopts fiber-optic positioning shot hole avoidance in permanent fiber-optic monitoring technology outside the casing, aiming to ensure the integrity of the casing external fiber-optic through accurate shot holes, so as to realize the real-time monitoring of single-hole fluid intake in the process of fracking, the micro-seismic events of fracking and the single-hole fluid discharge volume and the contribution to the gas production in the later stage of the discharge and extraction. ’

In order to guarantee the practicality and accuracy of the permanent fibre-optic monitoring technology outside the casing at a later stage, the technicians have done a lot of on-site tests and research in the early stage. Aiming at the protection of fibre optic cables in complex well conditions, high-pressure crossing at the wellhead and other technical difficulties, the technicians have carried out fibre optic monitoring services in more than 50 wells in China, and have worked out the precise positioning and radiation avoidance technology of APS locator. Meanwhile, in order to meet the demand for ‘real-time feedback guidance for fracturing construction and post-compression geological+engineering+production evaluation’, the company has carried out four types of monitoring, including ‘permanent optical fibre outside the casing, high-frequency pressure, downhole microseismic, and tracer’, so as to verify each other and improve the accuracy of evaluation. In order to improve the single-well production and economic efficiency of horizontal wells, the company has integrated various advanced testing and analysis methods to solve the problems of the planar characteristics of the fracturing network and the dynamic changes of the network during the whole life cycle of volumetric fracturing.

In addition, in order to ensure the smooth progress of fracturing, the technicians conducted strict pressure and temperature resistance tests on each optical cable locator at the factory, disassembled and inspected all the locators after pressure testing, and used them for fracturing construction on the premise that no leakage was detected and the locators' pressure resistance was judged to be able to reach 140MPa.

In order to further enhance the fineness of the work of connecting optical fibre into wells, the Oilfield Engineering Technology Department, Exploration and Development Research Institute, Oil and Gas Technology Research Institute, Oil Production Plant No. 3, Capacity Building Project Department and other departments and units actively docked with PetroChina's sister units, and sent special personnel to supervise the whole process of arriving, installing, entering and lighting optical fibre shotguns in the wells to ensure the safety of optical fibre in the wells.

At present, the permanent fibre-optic monitoring technology outside the casing applied in the 3H14-3 and 3H15-4 wells on the Yingpai 3H platform is following up the progress of the on-site fracturing design in real time and carrying out the monitoring work related to the injection and fracturing site.