Production Breakthrough from Channel Fracturing: A Seven-Year Journey in South Sulige Tight Gas Field

Abstract

Abstract South Sulige Operating Company (SSOC), a joint venture company between CNPC and TotalEnergies, has been the main operator in South Sulige gas field since 2011. After years of optimization on operation parameters, the annual post-fracturing production (absolute open flow, AOF) has reached a high plateau that outperforms offset blocks. Nevertheless, because of the fast-growing domestic gas demand, utilizing proper fracturing technology to further increase production has become crucial in recent years. This paper describes the successful design evolution of channel fracturing technology in Sulige tight gas field through a 7-year trial. Unlike the homogeneous proppant pack created in a conventional fracturing job, channel fracturing makes open and highly conductive channels by forming proppant pillars in the fracture through pumping proppant-laden fluid and proppant-free fluid intermittently. These channels are beneficial for improving effective fracture length, facilitating fracturing fluid cleanup, minimizing pressure drawdown along the fracture, and thus improving post-fracturing production performance. In 2016, the first channel fracturing trial was conducted on four wells in this field, with comparable treatment size to conventional jobs. The average 600-day cumulative production of target wells was 25% higher than that of offset wells, which demonstrated the enhancement to effective fracture half-length and thus more fracture-reservoir contact. In 2021, the design strategy was upgraded by incorporating a more aggressive pumping schedule to improve near-wellbore fracture conductivity while reducing fracturing fluid usage, with superior production results achieved from wells with mid to high reservoir quality. In 2022, the fracturing design strategy was set to maximize the production potential for high-quality wells with increased treatment size and further extended effective fracture length. This achieved production record of 87 MMscf/d AOF from a 2-layer vertical well. This result is even comparable to performance of offset horizontal wells. Besides the promising results, through the design evolution in these 7 years, a channel fracturing candidate selection workflow with associated design strategy has been established for a similar tight gas field. Channel fracturing has been proved an effective tool to create extended effective fracture length and maximize single-well production in South Sulige tight gas field, with potential cost saving from needing fewer wells to deplete the same reservoir area. This technology, along with the properly designed workflow described in this paper, can also be widely adapted in other tight reservoirs.