Research On Geological Model Of Reef Reservoir Of Wubaiti Gas Field Changxing Formation

The reef gas reservoirs of Wubaiti in Sichuan Province and Chongqing Municipality in Kaijiang County Kaixian ~ within the meaning and field Wubaiti area, which belongs to East Sichuan Datianchi steep north-dipping structural zone at the end of a local structure, like a short axis anticline, form a box-like profile. The reefs are developed in second section of chang and third section of chang of reservoir in the main. Reservoir that dominated by dolomite developed in the bottom of second section of chang and upper of third section of chang mainly. Its porosity and permeability are low. Its main problem now is the connectivity between gas wells and gas bearing scope which are still not very clear.In this paper, based on a large number of cores, logging and seismic data interpretation, and in combination with multi-disciplinary reservoir description techniques ,such as ,petrology, sedimentology, log interpretation, seismic inversion and so on to study the structural characteristics , reservoir distribution characteristics, characteristics of the rock , distribution of attribute and forecasting of favorable areas ,which for field development adjustment, enhancing and improving development effectiveness, and taping the gas field development potential to provide a basis and technical support .The following understanding are achieved mainly:(1) Overall, the physical property of dolomite is better than limestone. the value of dolomite of the acoustic logging and neutron logging value is lower, and the bilateral track of resistance was amplitude difference, which generally show low characteristics .But limestone layers opposite dolomite in characteristics of curves.The reservoir geological model makes a clear of distribution of the reservoir, porosity, permeability, gas saturation , which is mainly controlled by dolomite.(2) Through the reservoir geological model and from a static view, the whole gas reservoir is connected, but poor connectivity in the central structure. Through the distribution of all types of reservoirs, we found that Class II reservoirs are major. Favorable areas are TD74～TD10 well of the north of the regional structure and TD72～TD53well,TD021-4 well of the southern of the regional structure mainly.(3)The dynamic and static reserves were calculated, 50.72×10~8m~3 and 108.92×10~8m~3 respectively. The reasons of difference between static reserves and dynamic reserves of north well field are the dynamic reserves of calculated TD002-11well are low.