Testing of Production Profile Monitoring in Multi-Stage Fractured Horizontal Wells of Changqing Oilfield, China: Based on the Coiled-Tubing-Conveyed Gas Lift

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. This passage discusses establishing a stable flow state in the wellbore of low-pressure, low-permeability reservoirs to meet test requirements. The proposed method involves utilizing 2" coiled tubing along with logging tools for well testing. The process involves maintaining a stable flow or a consistent flow in the wellbore through annular negative pressure lifting. Coiled tubing is used to transport downhole logging tools for conducting fluid profile testing of the modified layer, analyzing fluid output, oil-gas-water distribution, among other parameters. This method rapidly identifies the main water-producing layers, with test data transmitted in real-time to surface receivers via single-core cable. Before entering the well, multiphase flow simulation software is utilized in conjunction with parameters such as well pressure, temperature, and fluid production index to design the depth for deploying the gas lift string. By employing gas lift for fluid evacuation to increase wellbore discharge and conducting continuous testing with the tubing string, this approach effectively addresses the challenges of low fluid yield and low success rate and operational efficiency in fluid profile testing of long horizontal well sections in low-production wells. It quantitatively interprets and analyzes the production contribution patterns of different stages, clarifying the water breakthrough mechanism and water production patterns in horizontal well segments during water injection development. Trials in three wells demonstrate that this technology fulfills the logging requirements for wells with a daily fluid production of less than 10m³ and horizontal sections up to 1500m in length. With an average effective testing time of 1.35 days (32.5 hours) per well, this technique provides a new method and technical means for monitoring and interpreting output in low-permeability oil fields with horizontal wells. The coiled tubing gas lift technology for fluid evacuation and fluid profile testing in horizontal wells represents an innovative integration of first-time cored coiled tubing operations, gas lift fluid evacuation, and Flow Imaging Testing (FIT) techniques. This innovation successfully overcomes the challenges of bridging and seamlessly integrating diverse technologies. It includes the establishment of operational procedure standards and risk prevention measures. This advancement carries substantial practical significance for the expansion and progress of oil and gas well-testing technologies in the petroleum industry.