Testing Of Production Profile Monitoring in Multi-Stage Fractured Horizontal Wells of Changqing Oilfield, China: Based On the CT-Conveyed ESP

Abstract

Abstract For horizontal wells of the Changqing ultra-low-permeability oil reservoir stimulated via the multi-stage multi-cluster fracturing, an innovative production profile monitoring technology, adapted to the long horizontal wellbore and low liquid production, was developed to provide references for adjustment and treatment of production performance of wells. The presented production profile test method at the stage/cluster scale for horizontal wells uses the coiled-tubing, internally penetrated by a load-bearable multi-core composite cable to connect the small-diameter electric submersible pump (ESP) and FSI production logging tool. The ESP and FSI logger are conveyed to the horizontal wellbore by the cable-through coiled- tubing. The cable-powered ESP drains the wellbore, and simultaneously, the coiled tubing drags the ESP and FSI logger along the wellbore to perform production profiling of frac stages/perforation clusters. The monitoring signals are transmitted via the composite cable to the surface, where the production monitoring, interpretation and analysis are completed. Increasing the well production rate with an ESP and dragging the tool string for continuous measurement effectively solve the technical challenges of the low success rate and inferior operation efficiency of production profiling in oil wells with low liquid production and extended horizontal wellbores. The test results, combined with near-wellbore and far-field acoustic fracturing propagation monitoring, enable quantified characterization of the production contribution pattern of stages/clusters and also the mechanisms and regularity of water breakthrough of horizontal wells in the case of water flooding. Testing in two wells demonstrates that the presented technology is technically competent for production logging in a horizontal wellbore no longer than 1500 m with various production rates. It provides a new methodology and technical approach for horizontal well production monitoring and interpretation in low-permeability oil reservoirs. This CT-conveyed ESP-assisted production profile testing technology for horizontal wells represents the first of its kind in the world, in terms of the integration of the cable-through CT operation, ESP artificial lifting and FSI production logging. Multiple challenges were overcome for technical crossover and integration, and the operation code was developed, which are practically valuable for the progress of the testing technology of oil and gas wells.