Fluid Inclusion Evidence for Oil Charge and Cracking in the Cambrian Longwangmiao Dolomite Reservoirs of the Central Sichuan Basin, China

Figure 2

The Longwangmiao Formation Well MX26 4924.28 m. Photos of cores and thin sections from the associated petrological observations. (A1) Algal silt, crystal dolomite with dissolution pores and cavities visible at core scale. (A2) Thin-section scan showing the intercrystalline pores and dissolution cavities of dolomite filled with asphalt. (A3) (-) Powder crystal dolomite with bright edges and a foggy center. (A4) (CL) Crystal showing a ring-shaped structure with intercrystalline pores filled with solid pitch; the foggy center of the crystals glows dark red and the bright edges glow scarlet under cathode light. (A5) (-) and (A6) (UV) Fill suite of intercrystalline pores of fine powder crystal dolomite: Dolomite, nonfluorescent solid pitch. (A7) (-) and (A8) (UV) Pore fill types identified in intercrystalline pores in fine powder crystal dolomite with crystals showing bright edges and foggy centers included the following: dolomite → nonfluorescent solid asphalt → yellow fluorescent oily asphalt. (A9) (-) and (A10) (UV) Pore fill types identified in intercrystalline pores in powder crystal dolomite dissolution pores included the following: dolomite → solid pitch → quartz →residual pores. (-): Plane-polarized light; UV: ultraviolet light; CL: cathodoluminescence.