Geology of Ziliujing Gas Field--The Gas Field Developed Earliest in the World

DING, CHUAN-BAI, Sichuan Petroleum Administration, Chengdu, China

Ziliujing gas field, located in Zigong municipality, Sichuan, is an asymmetric anticline, and well depth is generally less than 1300 m. There are eight gas- and brine-producing intervals. Tc-3 of the Lower Triassic is the main gas-producing horizon, which is a carbonate with a combination of fracture and intergranular porosities.

As early as 1500 years ago, the production of brine and natural gas was started; over 13,000 wells were drilled of which over 1000 wells were gas wells. The total area of different producing zones is about 22 km. The distribution and production of natural gas are controlled by structural faults. The gas sources supplied are beyond the limit of the structure. Tc-3 reservoir is a typical fissured reservoir, and most of the wells have the characteristics of (1) high initial production rate; (2) rapid depletion; and (3) long producing life. Owing to the favorable geological conditions; the great number of wells; outstanding ancient technologies in drilling, production, and transportation; comprehensive utilization; and very long production history, tremendous success is achieved in the de elopment of gas fields. The total cumulative gas production by the end of 1985 was 33 billion cubic meters in which 17.2 billion cubic meters are contributed by Tc-3 reservoir; maximum gas and brine recoveries have been achieved. So far the gas reservoirs have not been depleted and new discoveries have been found in recent years. The brilliant achievements of the ancestors remain.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)