Diagenesis and Fluid Flow Variability of Structural Heterogeneity Units in Tight Sandstone Carrier Beds of Dibei, Eastern Kuqa Depression

Figure 11

Photomicrographs from thin section (a, c, e, and f) and SEM (b and d) of wells DB102 and YN4. (a) Argillaceous sandstone is rich in igneous rock (IR) fragments deformed into pores as pseudomatrixes and (b) quartz grain (Qtz) is coated with fibrous illite (Ill) and siderite (Sd). (c) Most of the grains appear point-contacted and (d) illite smectite mixed layer clay surrounded the calcite crystal in tight cemented sandstone. (e) Gas-bearing sandstone contains intergranular and intragranular dissolution pores and pyrobitumen occurs in some pores. (f) Water-bearing sandstone also contains abundant rigid grains, some of which are cracked with microfractures.

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