Development status and prospect of tight sandstone gas in China

Abstract

As one of the important types of unconventional gas, tight gas is widely distributed in various major petroliferous basins in the world. The breakthrough of reservoir reconstruction technology and the reduction of development cost promote the scale and industrial development of tight gas. China is the third largest tight gas producer in the world and its yearly tight gas production is up to 470 × 108 m3 in 2020. In order to evaluate the development prospect of tight gas in China, this paper systematically summarizes domestic key technical series developed in the last 20 years' tight gas practice, after briefly analyzing the distribution and development history of tight gas resources all over the world. Then, the prospect of tight gas development in China is based on CNPC's fourth resource evaluation results. And the following research results are obtained. First, tight gas resource in China is abundant, accounting for about 10% of global resources, and its development is divided into two stages, i.e. the development evaluation stage and the development adjustment stage. Second, key technologies in the development evaluation stage include the establishment of genesis unit of effective reservoir, enrichment area selection, development index evaluation, well pattern and type optimization, reservoir reconstruction, and development scheme optimization. Third, the core in the development adjustment stage is enhanced gas recovery (EGR). The main technical means are well pattern optimization and infilling. Which can increase the recovery factor by 10%–20%. In addition, layer reviewing and reperforating, old well sidetracking, secondary fracturing, drainage and gas recovery, and pressurized production are also effective technologies. In conclusion, tight gas still has greater production potentials and development prospects in China. The potential tapping of produced proved reserves, the development of unproduced proved reserves and the effective development of new proved reserves are three important aspects to ensure the mid- and long-term development of tight gas. The first two aspects can support the yearly tight gas production to reach the peak of (700–800) × 108 m3 in 2030–2035 and keep stable production for more than 10 years. Moreover, the continuous development of new proved reserves will further support the stable production of tight gas until 2050–2060.