The Panhe thin coalbed methane development project, the first large-scale thin coalbed methane project in China, was put into operation on Aug 16, marking a new breakthrough in this sector for the country, according to its operator the China National Offshore Oil Corporation (CNOOC).
The project provides an important theoretical foundation for the efficient development and utilization of thin coalbed methane, and is of great significance in promoting the efficient development and utilization of coalbed methane and ensuring national energy security.
The Panhe thin coalbed methane development project is located in the southern part of the Qinshui Basin in Shanxi Province. It has built a total of 212 wells with a maximum daily output of 11,000 cubic meters per well and an average daily output of over 2,500 cubic meters.
Since trial operations began at the end of 2020, the cumulative output of thin coalbed methane has reached 180 million cubic meters, and the proportion of daily production has climbed to half of the total output in this block, realizing the efficient conversion from reserves to output.
Coalbed methane refers to unconventional natural gas associated with coal and stored in coal seams, commonly known as "gas". The development and utilization of coalbed methane not only solves the problem of coal mine gas control and ensures coal mining safety, but also provides a new source of clean energy for environmental protection.
Currently, the large-scale commercial development of coalbed methane in China is mainly in the main coal seams of the Qinshui Basin and the Ordos Basin. After years of development, gas production from these main coal seams has significantly decreased. In order to ensure gas production capacity replacement, technicians have been accelerating the development of thin coalbed methane.
"The Panhe block has multiple sets of thin coal seams, with considerable reserves of thin coalbed methane. However, as the average thickness of thin coal seams is only 0.6 meters, which is only one tenth of the thickness of the current main coal seams. Additionally, being stacked up in layers, the uneven distribution of single layers, and large vertical span of multiple layers make mining extremely difficult," said the company.
Thin coal seams generally refer to coal seams with a mining thickness of less than 1.3 meters. Statistics show that the recoverable reserves of thin coal seams in China account for 20 percent of the total recoverable coal reserves, or around 350 billion tons. Compared with the main coal seams, thin coal seams are like "layered cakes" with large differences in gas content and limited resource abundance. Therefore, thin coal seams have long been regarded as "marginal resources" in the development of coalbed methane.
In recent years, considering coal resources and its full development, CNOOC has continuously tapped into its mining potential to realize production capacity replacement.
By putting concentrated efforts on thin coal seams, the company has achieved technological innovations in thin coal seam identification, complex well network deployment optimization, large-span multi-level fracturing, and dual pressure and dual control gas drainage. It has built a comprehensive exploration and development technology system for thin coalbed methane, achieving the efficient use of thin coalbed methane for the first time in China.
The successful beginning of operations of the thin coalbed methane development project in the Panhe block has provided new ideas and created a new model for the economical and efficient development of thin coalbed methane in China, said the relevant person at CNOOC.
CNOOC will continue to strengthen scientific and technological innovation and explore new technologies for the efficient development of coalbed methane. The company will make new and greater contributions to the construction of an onshore trillion gas area and clean energy base, in a bid to ensure national energy security.
(Executive editor: Xie Yunxiao)
