Petrophysical characterisation of pore system for a carbonate reservoir in the HR structure

Tóm tắt

The purpose of reservoir characterisation is to fi gure out the spatial distribution of petrophysical properties such as porosity, permeability and water saturation that are key parameters for construction of the geological model. Characterisation of a carbonate reservoir is often diffi cult mainly due to the complexity of its pore system. This study presents an integrated approach to using well log and micro-geological data to characterise rock fabrics and their pore system for a carbonate reservoir in the HR structure. Based on well log data such as GR, PE, PHIN and RHOB, two major rock types of dolostone and limestone were identifi ed. A further combination with thin section and SEM analysis results indicated four types of carbonate rock fabric, namely limestone with grain-dominated grainstone, limestone with grain-dominated packstone, dolostone with grain-dominated grainstone and dolostone with grain-dominated packstone. For each identifi ed carbonate fabric, two types of pore were found, including interparticle and vuggy pores. The latter can be further subdivided into separate-vug pores and touching-vug pores. For the HR structure, the touching vug porosity and the interparticle porosity were estimated to be in the range of 1 - 3% and 1 - 8%, respectively. The inter-crystalline porosity, which might be considered as a subset of the interparticle porosity and could be estimated by SEM analysis, was found in the range from 1,5% to 3%. It is expected that the integrated analysis approach using well log and micro-geological data employed in this study can be applied to evaluate the characteristics of carbonate reservoirs at other well sites in Song Hong basin.