Slim Multistage Fracturing—One of the Most-Successful Solutions in the Most Recent 15 Years of China's Multistage Fracturing History

Abstract

Abstract Hydrocarbon resources have primarily been accessed from onshore environments. Most of the explored basins have matured, with some even nearing the end of their field lives. Production from these traditional resources has declined over the past few years, and new discoveries of vast resources are becoming rarer. Global exploration trends focused on deepwater (and even ultradeepwater) fields, deeper onshore formations, and unconventional resources are aligned with the focus of China's hydrocarbon industry. In 2021, China completed its first self-operated subsea deepwater gas project, Lingshui 17-2, and a series of new projects is planned for the next few years. In terms of developing deeper (> 4000 m) onshore formations, Sinopec Northwest set a record in Shunbei Field with an ultradeep oil development that reached 8874.4 m. Famous fields in China for unconventional hydrocarbon development, some of which are in deeper formations, include PetroChina Southwest in the Sichuan Basin, PetroChina Changqing in the Ordos Basin for tight gas/shale gas and shale oil, and Sulige in the Ordos Basin for tight gas. During China's 14th Five-Year Plan period, from 2021 to 2025, the proportion of unconventional oil and gas production will further increase, and production is expected to increase rapidly to align with the country's energy security strategy. Furthermore, the oil and gas industry worldwide has been placing a greater emphasis on carbon footprint reduction; while the number of new oil projects decreases every year, natural-gas projects, especially in deepwater environments and shale/tight reservoirs, have been rapidly increasing. This paper will focus on the unconventional hydrocarbon development methodology and discuss the evolution of fracturing technology, particularly multistage fracturing completion tools over the past two decades; then, the paper will review the various design concepts, features, and serviceability of representative completion tools during each fracturing period. A successful 10-year tight-gas sandstone application in Ordos, China, will be used to review the slim multistage fracturing sleeve (SMFS), the most-reliable fracturing string design, and its key operational improvements. The design has been informed by previous field knowledge and experiences, resulting in a simple, cost-efficient, and technology perfect adaptability tool that can be used to illustrate the development trend of multistage fracturing completion tools.