Research and Application of Composite Casing Cleaning Tools for Ultra-Deep and Highly Inclined Wells

With the continuous deepening of exploration and development in the Tarim Oilfield, the number of ultra-deep and highly inclined Wells and horizontal Wells in front of the Kuqa Mountain has been increasing year by year, and the liner adopts a composite method of φ139.7 mm casing and φ127.0 mm casing. In completion operations, it is necessary to ensure the cleanliness of the wellbore. Poor wellbore cleanliness can easily lead to reservoir contamination, premature setting of the packer, and difficulty in lowering the production string. The combined scraping string with two types of scrapers has the risk of stuck pipe and obstruction during the operation. The conventional method of scraping the casing by passing through the string has good results, but it has a long operation cycle and high cost. This severely restricts the development efficiency. In response to the above problems, through a series of studies including structural optimization, material and heat treatment selection, scraper strength simulation, and indoor experimental evaluation, a “one-pass” composite casing scraping tool was successfully developed. This tool can rotate both the straightening sleeve and the scraper. When stuck, it can lift the pipe string, cut the emergency release pin, and achieve synchronous rotation to remove the stuck, completely eliminating the traditional multi-pass process. The tool has been successfully applied in the completion site of the ultra-deep Wells in Tarim Oilfield, reducing the operation cycle of a single well by nearly 72 h and increasing the operation efficiency by more than 60%. It has verified its reliability and efficiency under complex conditions, significantly shortened the wellbore preparation time, saved operation costs, and injected strong impetus into the efficient development of ultra-deep oil and gas in China.