Reservoir Quality and Its Control Factors of Complex Fault Block Reservoir in Continental Faulted Basin, Case Study in the Wang Guantun Area, Bohai Bay Basin, China

Abstract

Continental faulted basins are widely distributed in eastern China. Many of these basins, in which the faults block oil and gas reservoirs, have been explored. The heterogeneity of the reservoirs in fault block is very strong, shich restricts the further efficient development of these kinds of oil and gas fields. In this study, porosity and permeability tests, the use of thin sections of rock, mercury injection experiment and CT scan were used to investigate reservoir quality characteristics and control factors. The results showed that the content of quartz, feldspar, and debris in rock had a significant control function on the quality of the reservoir. Reservoir performance improved with increase of quartz and feldspar content, and worsened with increase of debris content. Taking the Ek1 reservoir in the Wang Guantun area as the specific research object, we developed the following understanding. On the one hand, the main compaction in the study area was mechanical compaction. When the compaction rate was greater than 60%, the porosity and permeability were inversely proportional to the compaction rate. On the other hand, dissolution pores were relatively developed in the study area, and the main types of dissolution were intragranular and intergranular dissolution pores. When the surface porosity of the dissolution pore was over 9.2%, porosity increased significantly the increase of dissolution surface porosity. This showed that dissolution surface porosity had greatly improved the reservoir porosity in this range.

Experimental Study on Improving Oil Recovery Mechanism of Injection–Production Coupling in Complex Fault-Block Reservoirs

“…Different from conventional fractured carbonate reservoirs and low-permeability reservoirs, complex fault-block reservoirs are characterized by poor physical properties, more complex structural development, loose reservoir lithology, and strong microscopic heterogeneity [20][21][22][23]. The mechanisms by which injection-production coupling development improves the water-driven development effect of complex fault-block reservoirs and the oil production characteristics of heterogeneous reservoirs have not been deeply studied.…”