Integrated controls of tectonics, diagenesis and sedimentation on sandstone densification in the Cretaceous paleo-uplift settings, north Tarim Basin

Diagenetic Controls on Tight Sandstone Reservoir Quality: A Case Study from the Huaqing Oilfield, Ordos Basin

“…The full pore size distribution curves of diagenetic facies A, C, and D all show a single-peak pattern, and the pore sizes corresponding to the peak positions decrease in order, with 0.1–0.2 μm, 0.07–0.1 μm, and 0.007–0.13 μm, respectively, where the diagenetic facies A is mainly dominated by residual intergranular pores due to the high content of brittle minerals. Previous studies have shown that the presence of brittle minerals makes the reservoir more difficult to be compacted under the same stress conditions . The brittle minerals effectively balance the strength of compaction, so the pore structure of diagenetic facies A is characterized by a relatively uniform pore size distribution, and the original pore morphology is well preserved.…”

“…Quartz tends to dissolve in alkaline environment, and the study area is dominated by feldspar dissolution, thus indicating that acidic fluids play a major role in the study area. 79 The acidic fluid enters the reservoir and dissolves the minerals along the connecting pore throats, and differential dissolution occurs within the reservoir, with the better connected part being strongly dissolved and the poorly connected part being weakly dissolved. As a result, pores of different sizes are distributed, and the reservoir is nonhomogeneous.…”

“…Previous studies have shown that the presence of brittle minerals makes the reservoir more difficult to be compacted under the same stress conditions. 79 The brittle minerals effectively balance the strength of compaction, so the pore structure of diagenetic facies A is characterized by a relatively uniform pore size distribution, and the original pore morphology is well preserved. Most of the pores in the diagenetic facies C samples are filled with cement, resulting in a sharp decrease in pore volume.…”