The company has made substantial progress in the exploration of the Paleozoic coal seam section in the Yichuan area of Yan'an, and the daily production of a single well for gas testing exceeded 30,000 cubic metres of coal bed methane, which set a new record for the highest daily production of this type of resource in the Yan'an gas field.This indicates that the Yan'an gas field has huge potential for deep coalbed methane exploration and development.
Coalbed methane, commonly known as gas, is an unconventional natural gas, and coalbed methane with a burial depth of more than 1,500 metres is known as deep coalbed methane in the industry.Compared with shallow and medium coalbed methane, the mechanism of deep coalbed methane is more complex, and the exploration and development is difficult and costly.
Wan Yongping, chief geologist of Yanan Oil & Gas Field Company, introduced that the depth of coal beds in Yanan gas field is more than 2,000 metres, and compared with the surrounding coal bed methane fields that have been discovered, it has the geological characteristics of "greater depth of coal beds and significant thinning of the thickness", and the development of Yanan gas field is facing the problems of blank technological experience and complex processes.
In order to promote the Yan'an gas field to increase reserves and production, Yanchang Oil & Gas Field Company organised industry research, introduced experts, innovated around four key core technologies, namely, geology, drilling, fracturing, and extraction, and carried out pilot tests of coalbed methane horizontal well groups, actively explored paths applicable to the exploration and development of deep-seated coalbed methane in the Yan'an gas field, and preliminarily formed the process of drilling horizontal wells in thin coal seams and "dense network" volumetric fracturing transformation technology.Initially, a horizontal well drilling system for thin coal beds and a "dense network" volumetric fracturing transformation technology system have been formed.
According to the report, the company preferred conventional wells for coal bed gas test in the exploration favourable area, and industrial gas flow was obtained in 4 wells, and substantial progress was made in resource exploration.