The burial depth of the Changxing Formation in Yuanba gas field

Sichuan Basin

is nearly 7 000 meters

the biological reef-shoals are small in scale and scattered in distribution

and the reservoirs are small in thickness and poor in poroperm characteristics and connectivity.In addition

the gas field has a complex gas-water contact

and high contents of hydrogen sulfide and carbon dioxide.All of these make the gas development in the study area very difficult.For effective development of the gas reservoir

a series of technologies has been innovatively integrated to finely characterize the reef-shoal reservoirs and their inter architecture.Firstly

the major factors controlling the development of favorable reservoirs are summarized and a reef-shoal development pattern is built based on study of stratigraphy

sedimentary facies

modern reef-shoal deposition and diagenesis.Secondly

under the guidance of the reef-shoal development pattern

logging interpretation and reservoir identification are performed and a forward geological model is established by integration of well-seismic data

and then the reservoir distribution is predicted through sensitive seismic attributes extraction and inversion.Thirdly

the distribution of reef-shoal reservoirs is characterized by integrating geological constraints with seismic techniques

such as profile identification

plane constraint

3D boundary delineation

and connectivity detection.Finally

the reservoir connectivity and the spatial distribution of favorable reservoirs are analyzed.Via this workflow

three structure models of reef-shoal reservoirs are established to support the production planning and well deployment in the Changxing Formation of Yuanba gas field.