Characteristics And Forecast Model Of Carbonate Subtle Shoal Reservoir

The interest of carbonate exploration activity have been changed from structural hydrocarbon reservoir to structural-lithologic hydrocarbon reservoir and lithologic hydrocarbon reservoir with the depth degree of exploration.Limited by the seismic scale resolution,how to forecast the distribution of reservoir by rule and line is a pivotal condition of the strong reservoir heterogeneity carbonate exploration activity. This thesis takes examples for the T₁j² gas reservoir of Moxi Structure and T₁j² of Longnvsi Structure of the middle of Sichuan basin and the Cambrian Xixiangchi Group gas-bearing bed of Weiyuan Structure of the south Sichuan.It is under the direction of Carbonate Sedimentology,Reservoir Geology,Logging Geology,and Cycle Stratigraphy.Through the elaborate field exposed profile and core observations,using the log data sufficiently,base on the veracious identification of grainstone,the log interpretation model of grainstone has been constituted and the development interval has been searched in this thesis.The master control element of the development and distribution of the carbonate shoal facies in the space-time rule have been elucidated.The development of carbonate shoal which is controlled synthetically by the palaeostructure,palaeogeomorphology,palaeobathymetry and palaeohydrodynamic has been shown.It suggests that the submarine palaeohigh within the platform is the advantaged development area of carbonate shoal.Studying the characteristics of carbonate shoal reservoir,the intragrannlar,moldic,residual intergrannlar and solution-enlargment intergrannlar pores which are the main reservoir space of shoal reservoir have been shown.It believes that the reservoir of different pore types has the different pore-throat and poroperm characteristics.Base on the study of reservoir diagenesis,researching the genetic mechanism of shoal-controlling reservoir,the early karstification and primary intergrannlar pores preservation which are the main genetic type of carbonate shoal reservoir have been shown.And it suggests that rebuilding physiognomy in the depositional stage is one of the effective methods to forecast the concealed shoal reservoir.Under the direction of this method,the fine reservoir certification rate of the sequent 12 development wells of T₁j² gas reservoir of Moxi Structure achieves 100%.At the same time,the validity of this geological model had been approved by the new wells penetrated Cambrian Xixiangchi Group of Weiyuan Structure.