Technique And Application Of Geology-Seismic Reservoir Prediction Of Karst Reservoir In Yubei Area

Karst reservoirs in Yingshan formation of Lower Ordovician have a good showof oil and gas on Markit slope in Yubei area, showing good prospects of oil and gasexploration of these Ordovician carbonate reservoirs. However, the fracture-cavedevelopment scale and spatial distribution of karst reservoir in Yingshan formationchanged severely, and reservoir heterogeneity is very strong because of the repeatedlytectonic movements and the development of the fracture system. This makes theexploration into a difficult situation in the area. Therefore, the main controllingfactors, the vertical and horizontal distribution patterns and development mode ofthese karst reservoirs need furture research. Comprehensive prediction of Geologicaland seismic information is presented in this paper, based on geological model andunderstanding macro guidance and constraint, the advantage of continuous spacedistribution of seismic data is given full play, and comprehensive prediction ofgeological and seismic reservoir are carry out with a variety of seismic technicalmethodsThis paper studied the geological characteristics of Yingshan karst reservoir inlower Ordovician in the3D seismic research area of YuBei1Well, and point out thatthe reservoir space is multiplicity, which mainly consists of cracks, dissolved poresand holes. The reservoir types mainly contain cracks-dissolved hole reservoir, cracksreservoir and dissolved hole reservoir. These constructive transformations of fracturesystem, paleotopography, tectonic movement, karstification, unconformity surfacecontrolled the development of karst reservoirs together. The tectonic movementbrought about the fracture system and regional development of fractures, providingpercolation channel for karst reservoir development, and then controlled the flowdirection of surface and ground water, so as to the karst reservoir development along the fault zone; Tectonic movements control the uplift and subside of the crustal, anddetermine the paleotopography and the degree of stratigraphic exposure. Thepaleotopography regulate the distribution of favorable karst development zones;Unconformity surface controls the period of karst development. Crake-hole filling is adestructive diagenesis, and reduces the reservoir space within the oil and gas. Basedon the discussion of the controlling factors of reservoir development and comparativeanalysis of the characteristics of reservoir development, fracture system and karstpaleotopography are the most important main factors in Yingshan reservoirs, andfracture detection and paleotopography restoration should be the core of karstreservoir prediction.The highlands unaka area on paleo-geomorphic karst slope is the favorable zonesof karst reservoir development, and the range of karst development is related to theground water table, Paleo-morphologic restoration and analysis define our researchdirections to find the favorable reservoir development area. Seismic data with awealth of geological information and a series of seismic reservoir predictiontechnology are required to make comprehensive research and analysis for thedistribution characteristics of reservoirs. Spectral decomposition is adopted to reflectthe distribution of the fracture-cavity reservoir based on the different frequency tuningamplitude value; dip azimuth attribute can identify large-scale fault system; curvatureattribute reflects rupture cracks caused by stratum structure bending deformation;structure cube technology can accurately identify the discontinuities of formation; theimproved ant tracking algorithm can effectively detect tectonic shear cracks andexpansion cracks caused by the effect of formation extrusion; the comprehensiveresearch and analysis results of four methods can define the fracture developmentzone. The matrix porosity of the reservoir of Yingshan formation is low, anddissolution pores and caves make great contribution to the formation porosity, andporosity inversion can be used to identify the development zone of dissolution poresand caves. Finally, paleotopography and fault zone as one reference factor of reservoirprediction in study area; cracks and dissolved pores as one important criterion todetermine the pros and cons of reservoir development; logging reservoir evaluationresults as one important evaluation reference, and also combined with drilling oil andgas shows, seismic reservoir prediction is made to find the favorable exploration area.In the geological point of view, seismic prediction results of karst reservoir ofYingshan formation in Yubei area are discussed, and a reasonable interpretation ofgeology is given, and the completed geological-seismic reservoir prediction is realized. The effectiveness of reservoir prediction methods applied in the study areahas also been fully reflected. On this basis, karst reservoir development mode ofYingshan formation is established, which provides reference for the furtherexploration of the research area.Different types of reservoir, which have different geological characteristics, arecontrolled by different main factors, corresponding to different seismic responsecharacteristics. Through comparative analysis of the seismic response characteristicsof reservoirs with different main factors in different regions, geophysical informationcan assist the analysis of the main factors in reservoirs, and once the seismic responsecharacteristics are not matched with the main factors, problems are detected timely,which guide the geological-seismic reservoir comprehensive prediction.