Architecture Characteristics And Distribution Prediction Of Karst Reservoirs From The Ordovician Yingshan Formation In Tahe Oilfield

Carbonate karst reservoir are characterized by complex spatial distribution and interconnected relationships and can often form large oil and gas fields.Taking the karst reservoir of Yingshan Formation of Ordovician in Tahe oilfield as the object,using geological theory and geophysical methods to comprehensively analyze the architectural characteristics of karst reservoir,establishing the development pattern of karst reservoir and predicting the distribution of karst reservoir.Classifying the reservoir space of karst reservoir of Yingshan Formation,analyzing different logging response characteristics,summarizing sensitive parameters,for example,DEN,V_sh,1/R_LLS and?R,etc.Establishing the cross-plots and identifying the fractured,pore-fractured,pore-cave karst reservoirs.According to the karst reservoir of Yingshan Formation in the study area,the imaging logging is used to characterize the karst elements,including:dissolution expansion fractures,dissolution pore,and caves.Meanwhile meticulously depicting the architecture of the karst reservoir.In paleo-burial hill exposed area,longitudinally,according to the single well of the karst reservoir's characteristics,identifying the epi-karst reservoir,vertical-vadose karst zone and the horizontal-phreatic karst zone.Comprehensively analyzing the configuration and relationship between the main controlling factors of reservoir development,such as paleogeomorphology,fracture and unconformity.First,the study area developed a complete karst landform:including karst highland,karst slope and karst depression.In paleo-burial hill exposed area develops crust karst reservoir.In the slope area develops bedded karst reservoir,controlled by unconformity and fault respectively develops the layered distribution pore-cave reservoir and the vertical fracture reservoir.Overall the superimposed pattern of vertical reservoir,horizontal reservoir and bedded reservoir are formed,then establishing the developed pattern of karst reservoir.Using three-dimensional seismic data,the characteristics of three kinds of seismic responses:red-trough reflection,disorder strong reflection and bead-shaped reflection are identified,the reflection characteristics of different tectonic parts are analyzed,the dynamical attributes(amplitude attributes,frequency attributes,energy-attenuated attributes)and the seismic geometric attributes(coherence,edge detection)are calculated and analyzed.According to the characteristics of seismic attribute identification of karst reservoir,the distribution of karst reservoir profile is defined.Describing karst water system,according to reservoir development pattern,through attribute analysis,predicting the distribution of reservoir,considering paleogeomorphology,unconformity and fault as constraints forming the basic characteristics of"geomorphic zoning","unconformity and fault controlling band".