Seismic Response Characteristics And Distribution Prediction Of Reefs In The Changxing Formation In The Damaoping Area

As a typical lithologic reservoir,reef has the characteristics of high porosity and permeability,large reservoir thickness,high reserve abundance and large single well oil and gas production,and has a very broad prospects for exploration.Reef development is closely related to sedimentary facies belts and sedimentary environments.Reef types are diverse.The internal lithology and physical properties of the reefs are complex,and the reefs show strong heterogeneity both vertically and horizontally.The seismic response characteristics at the top of Changxing Formation are complex.Phenomena such as coaxial dislocation,transverse energy asymmetry and phase inversion often occur.Reefs are scattered in spatial distribution.The large-scale reefs have clear seismic response characteristics,and the small-scale reefs are difficult to identify in seismic data.The difference between reef reservoir and non-reservoir is small,and the difference of overall geophysical characteristics is not big.It is difficult to identify reef reasonably and effectively with conventional single geophysical method.Reef exploration in Changxing Formation is complex and seismic data interpretation is multi-solution.At present,there are two main problems in bioherm reservoirs:one is the determination of seismic response model of bioherm in Changxing Formation and the effective identification of bioherm;The second is the delicate description and distribution prediction of reef boundaryIn view of the above-mentioned problems that need further research,this paper takes the reef in Changxing Formation in DMP area of Eastern Sichuan Basin as the research object.Comprehensive analysis combined with geological,seismic and logging data.A typical theoretical model of reefs is established to simulate the seismic response of reefs.Four seismic reflection modes of reefs in Changxing Formation are summarized to guide reef identification and fine structural interpretation of the target layer Changxing Formation in the study area.Based on ancient landform analysis and seismic facies analysis technology,favorable sedimentary facies zones of reefs are divided.Seismic attribute analysis technology is used to optimize the sensitive attributes of reefs,including coherence,instantaneous phase and amplitude attributes,to depict the boundary of reefs,and to determine the distribution range of reefs from the plane.By summarizing the seismic response characteristics and distribution rules of reefs in the study area,favorable exploration targets are selected and a set of seismic identification methods for reefs is established,which has certain guiding significance for seismic identification of reefs in the study area or similar areas.