Improving the production efficiency of high rank coal bed methane in the Qinshui Basin

Abstract

There are abundant high-rank coal bed methane (CBM) resources in China, accounting for one third of total CBM resources. Its efficient development and utilization is of great significance to guarantee the national energy strategic security, diminish the hidden danger of coal mine production and reduce carbon dioxide emission. In order to solve the "four lows" problem (i.e., low effective utilization ratio of proved reserves, low productivity targeting ratio, low single-well production rate and low development profit) restricting the development of high-rank CBM industry in China, this paper deeply analyzes the core problems restricting the development of high-rank CBM. Based on this, several new methods of production control, area selection and evaluation are put forward by taking multiple measures, such as paying the same attention on theoretical research and technological research & development, carrying out laboratory research and field test in parallel and conducting large-scale construction and benefit development simultaneously. And the following research results are obtained. First, the geological difference between CBM and coal mine, the difference in reserves recoverability, the adaptability of engineering technology and the scientificity of production are the main factors restricting CBM development effect. Second, "Four-element" production control theory, methane-leading engineering transformation method and methane-leading production control theory are proposed, which provides guidance for the development of a series of technologies for the efficient development of high-rank CBM. Third, in practice, the control degree of quality reserves is increased from 32% to 80%, the success ratio of development wells is increased from 60% to 95%, the average single-well daily gas production of vertical wells is increased by about 1100 m3, the drilling cost of horizontal wells is reduced by 50%, and the operation cost per cubic meter of gas is reduced by 24%. In conclusion, the established technology series for the efficient development of high-rank CBM actively promote the efficient CBM development in the Qinshui Basin. The yearly CBM production of PetroChina Huabei Oilfield Company is expected to reach 20 × 108 m3 in the middle of the "14th Five-Year Plan", which promotes the strategic development of CBM industry in China.