| Abstrakt: |
The reservoirs from Chang 4 to Chang 7 of the triassic Yanchang formation in Ordos Basin are the main production strata in the Wuqi Oilfield, China. To supplement formation energy and increase reservoir diversion capacity, adjustment measurements such as water injection and hydraulic fracturing are needed urgently. Research on reservoir sensitivity is essential to reduce reservoir damage and minimize developmental impacts. Based on an analysis of the lithologic characteristics, cementation and pore structure of the Chang 4-Chang 7 reservoirs, reservoir sensitivity flow evaluation experiments were conducted according to the evaluation criteria for a clastic reservoir. Reservoir sensitivity types and sensitivity and influencing factors were analyzed. The experimental results show that the different types of reservoirs had different reservoir sensitivities. The Chang 4+5 reservoirs were moderately to weakly sensitive to velocity, weakly sensitive to water, weakly sensitive to acidity and weakly to moderately sensitive to alkalinity. The Chang 6 reservoir was weakly to moderately sensitive to velocity, weakly to moderately sensitive to water, moderately to strongly sensitive to acidity and weakly sensitive to alkalinity. The Chang 7 reservoir was weakly sensitive to velocity, not at all to weakly sensitive to water, weakly to moderately sensitive to acidity and weakly sensitive to alkalinity. Reservoir sensitivity is not only affected by the composition and distribution of sensitive minerals but also by the heterogeneity of the pore structure of the reservoir. Therefore, the sensitivity characteristics of different types of reservoirs should be adjusted accordingly during water injection and fracturing. [ABSTRACT FROM AUTHOR] |
