Application of expandable tubular plugging technology in long open hole wells with severe lost circulation

The drilling of natural gas wells in the Sichuan Basin often faces the plugging demand of long open hole section, multi-pressure system and high pressure-bearing capacity, but the existing chemical plugging and pressure-bearing technologies cannot fully meet the requirement of pressure-bearing target and time efficiency. In order to solve the problem of severe lost circulation in the natural gas wells in the Sichuan Basin, this paper researches and develops high-performance expandable tubulars, supporting tools and liquid system, and carries out performance evaluation and application boundary analysis of expandable tubulars. The expandable tubular based open hole plugging technology is formed and applied on site. The following research results are obtained. First, the low carbon manganese alloying technology, the third generation of Mn-TRIP steel formula and the high standard manufacturing process can greatly improve the performance of expandable tubulars. The impact toughness of the newly developed expandable tubular after expansion is greater than 105 J, and the collapse strength is more than 20 MPa. Second, based on the measured connection efficiency of the threaded joint, the application boundary range of the high-performance expandable tubular is established by referring to API standard and the calculation method of application boundary range of the J55 expandable tubular. Third, based on the high-performance expandable tubulars, combined with hydraulic reamer, suspension sand cleaning fluid and cementing slurry, the standardized construction process of "hole reaming, expandable tubular running, expandable tubular expansion, and drilling recovery" is formed for the expandable tubular based open hole plugging. In conclusion, this technology has been successfully applied eight times in the Sichuan Basin, with a cumulative operation length of 5 177.81 m and a pressure bearing capacity of more than 35 MPa, and all of their open hole sections are plugged effectively. What's more, this technology is expected to be an effective method for solving the problem of severe lost circulation, and it can be popularized and applied in well structure prolongation, high-pressure brine isolation, wellbore repair and other fields. © 2023 Natural Gas Industry Journal Agency. All rights reserved.