5.3.2. Differential porosity loss due to TSR-involved solid bitumen precipitation
Fig. 14. Variation of solid bitumen concentrations as BX-795 function of intercrystal porosity for carbonate reservoirs in the Puguang gas field.Figure optionsDownload full-size imageDownload as PowerPoint slide
5.3.3. Differential porosity loss due to calcite precipitation
The distribution of calcite cements in the Puguang gas field reservoirs shows considerable heterogeneities. (1) The upper part of the second member (above 4940 m) and the third member of the Feixianguan Formation have relatively high concentrations of calcite cements, whereas carbonate reservoirs below 4940 m, including the lower part of the second member and the first member of the Feixianguan Formation, have minor or no calcite cements (Fig. 3). (2) Reservoirs above 4940 m display considerable variations in calcite cements, from less than 0.5% to 30%. (3) At a thin-section scale, some pores are menstruation fully filled by calcite cements, and others have only minor or no calcite cements (Fig. 4E). These heterogeneities in calcite distribution resulted in differential porosity loss in the reservoirs (Fig. 3).
Fig. 14. Variation of solid bitumen concentrations as BX-795 function of intercrystal porosity for carbonate reservoirs in the Puguang gas field.Figure optionsDownload full-size imageDownload as PowerPoint slide
5.3.3. Differential porosity loss due to calcite precipitation
The distribution of calcite cements in the Puguang gas field reservoirs shows considerable heterogeneities. (1) The upper part of the second member (above 4940 m) and the third member of the Feixianguan Formation have relatively high concentrations of calcite cements, whereas carbonate reservoirs below 4940 m, including the lower part of the second member and the first member of the Feixianguan Formation, have minor or no calcite cements (Fig. 3). (2) Reservoirs above 4940 m display considerable variations in calcite cements, from less than 0.5% to 30%. (3) At a thin-section scale, some pores are menstruation fully filled by calcite cements, and others have only minor or no calcite cements (Fig. 4E). These heterogeneities in calcite distribution resulted in differential porosity loss in the reservoirs (Fig. 3).