| In view of the production problems such as difficult identification of deep-ultra deep weak energy carbonate
fault-karst, unclear connectivity of fault-karst carbonate reservoir, as well as high yield of “small beads”, low production
of “big beads”, “low beads” producing oil, and “high beads” producing water，on the basis of the understanding of the
geological model of fault-karst configuration, the geometric shape characteristics, scale and internal lithofacies of faultkarst
are characterized by using dynamic and static production data, and then the feasibility of depicting the outline and
internal structure of fault-karst is explored. The quantitative description techniques are introduced as the following three
aspects:(1) The seismic wave decomposition technique is applied to remove strong reflection in the overlying strata and
highlight the response characteristics of weak energy fault-karst reservoir. It is an important basic work for fine
description of the interior of the fault-karst. (2) The boundary of fault-karst is described by multi-scale fault detection in
frequency domain, which realizes the fault identification of weak seismic response, and can provide better and more
accurate fault information. (3) Combined with geological and logging information, the internal lithofacies distribution of
fault-karst are identified by using fracture-cavity lithofacies inverse technique, so that the spatial heterogeneity of fracturecaveity
reservoirs can be quantitatively evaluated from the perspective of lithofacies. The key techniques of seismic
characterization of carbonate fault-karst configuration provide a new idea for efficient well location optimization of faultkarst
reservoir. The drilling success rate of fault-karst reservoir is increased from about 75% to 94% after the development
idea of reservoir is changed from point cave to three-dimensional fault-karst. In practice, the research results can be used
to evaluate the connectivity of fault-karst reservoir, optimize efficient wells, tap the potential of remaining oil, and
propose measures for fault-karst reservoir and improve oil recovery. |
