| Author's Name: NI Chao1, ZHANG Benjian2, CHU Chunbo3, HAO Yi1,4, GU Mingfeng1,
PAN Liyin1,4, LI Mengying1, YAO Qianying1, ZHU Kedan1 |
| The Permian Qixia and Moukou formations in Sichuan Basin have been the key targets for natural gas
exploration since 1950s. With the continuous deepening of the exploration and development, it has been different of the
exploration ideas and directions. In order to clarify the next direction of natural gas exploration, based on a combination of
drilling, outcrop, logging, seismic and geochemical data, this paper systematically analyses the geological questions and
explorational domains of Qixia and Moukou formations. The results indicate that: (1) The Qixia Formation-Maokou
Formation in the Sichuan Basin is mainly a platform depositional system, which can be divided into three stratigraphic
sequences (SQ1, SQ2, and SQ3 from bottom to top). In addition to the western Sichuan platform margin, the Qixia
Formation-Maukou Formation in the central and eastern Sichuan Basin developed a number of high-energy shoals in the
highstand system, encompassing an area of over 40,000 km². This has laid a solid foundation for the development of shoal
reservoirs. (2) The primary reservoirs of the Qixia Formation-Maukou Formation are pore-cavity dolomite, karst
fractured-vuggy limestone, and microporous-microfractured marlite of which, pore-cavity dolomite is the main reservoir
of recently explored. The dolomite of the Qixia Formation is primarily developed in the Guanyuan-Beichuan-Ya’an
E’mei area in the west of the Sichuan Basin, while the main deposits of the Maokou Formation are distributed in
Xuanhan-Wanzhou, Guanyuan-Jiange, and Jiange-Guangan-Fengdu area. Karst fractured-vuggy limestone reservoirs
are mainly developed in the central Sichuan to southern Sichuan region. Microporous-microfractured marlite reservoirs
are mainly distributed in local areas of northern and eastern Sichuan, and the research level is relatively low. (3) Four
realistic fields and two potential fields can be distinguished in the Qixia-Maokou formations natural gas exploration in the
Sichuan Basin. The dolomitized shoal zone of the Maokou Member 2 in the northern-central-eastern Sichuan Basin is the
most significant realistic exploration field for the Middle Permian natural gas storage and production. We need to
accelerate the comprehensive evaluation of reservoirs and submit or upgrade natural gas reserves. The isolated dolomited
shoal in the lower sub-member of the Maokou Member 2 in the eastern Sichuan Basin is anticipated to be one of the most
significant potential exploration field in the future. We need to deepen the research and finely characterize the distribution
range of reservoirs, striving to achieve a breakthrough in this field as soon as possible and promote it becoming a
replacement field for natural gas exploration. |
