Reservoir Prediction Technique Of Carbonate Of Fracture-cavity Type And Its Application In The South Area Of Tahe Oilfield

This dissertation is based on plentitude of research information of cores, drilling, well logging, testing, VSP, and seismic data, depending on regional sedimentary background, seismic phase, and sedimentary facies jointly interpretation, founded on the research of reservoir geophysics response characteristics of fracture-cavity type carbonate rock, and relying on the reservoir seismic prediction technique of carbonate of fracture-cavity type. Thus, this research is one involving multi-methods and multi-disciplines. What's more, Ordovician carbonate reservoir of fracture-cavity type in south of Tahe oilfield is predicted, stratigraphic distribution characteristics of each era is discussed, fault system with its spatial distribution regulation in the research area is studied, and the Ordovician trap of stratigraphic unconformity-carbonate reservoir of fracture-cavity type is evaluated. Finally, the spatial development distribution characteristics of carbonate reservoir are identified and illustrated.The dissertation includes the following contents:Chapter I Preface. This chapter is mainly discussing the origin and significance of this dissertation, introducing the status quo of carbonate reservoir prediction technique at home and abroad and the exploration situation and problems of Tahe oilfield, illustrating the research approach and technique support of this dissertation, and indicating the primary contents and workload. Counting on the geological information of research area, drilling data, well logging and testing, structural, sedimentary, and reservoir characteristics, seismic sequence, and reflection structure is researched and analyzed. Seismic response characteristics and well logging response characteristics and their relationship is studied. By analyzing reflection characteristics, structure, fine seismic phase, sedimentary facies, rock physics, response mechanism of seismic wave, and several seismic attributes, reservoir response model is built up and appropriate reservoir prediction technique applied to this research area is discussed to fulfill the geological target of reservoir prediction. Correspondingly, reservoir prediction and evaluation job can be finished purposefully, so that exploration target and measurement can be suggested.Chapter II Introduction of research on geophysics response characteristics of carbonate reservoir of fracture-cavity type. This dissertation is based by researching on well logging response characteristics of carbonate reservoir of fracture-cavity type, forward modeling of fractured reservoir from two perspectives of physical and numerical model experiment of fracture, forward modeling of cavity reservoir also from perspectives of physical and numerical model experiment of cavity. Moreover, the theory of physical and numerical modeling of fractured reservoir and cavity reservoir, the method of modeling and the analysis of modeling result are introduced detailedly. Therefore, seismic response characteristics and the geophysical recognition model of carbonate rock reservoir are concluded.Chapter III Reservoir prediction technique of carbonate of fracture-cavity type. This technique includes fine interpretation technique of seismic data and prediction technique of carbonate rock reservoir. In the section of fine interpretation technique of seismic date, it mainly introduces integrated recognition and calibration technique of structural layer and reservoir, and fine interpretation technique of seismic data. In the section of prediction technique of carbonate rock reservoir, it refers extraction technology of seismic attribute parameters, 3D seismic coherence and discontinuity detection technique, cluster detection technique of strong amplitude, 3D seismic visualization technique, seismic phase classification technique, differential velocity analysis technique, and differential AVO envelopment analysis technique and so on. Moreover, all techniques' theories, their implementation, and their application conditions and expected effect are discussed thoroughly.Chapter IV Geological background of south area of Tahe oilfield. This chapter includes the location of research area, exploration degree, exploration history, regional tectonic setting, depositional characteristics, source rock, reservoir development and reservoir-seal assemblage of main target layer, and conditions of hydrocarbon migration and preservation and so on. The research area locates in Che county and Shaya County of Sinkiang. Its structural position is at southwestern pitching end of Akakule sub-uplift, which lies in the Shayalong uplift zone of northeast depression area of Tarim basin. This area experienced multistage tectonization, especially the middle stage of Caledonian movement which prompted the carbonate rock of middle-lower Ordovician to be weathered and denudated, karst development, and formation of carbonate karst reservoir which is beneficial to hydrocarbon accumulation and pool formation. Moreover, the mudstone and lime mudstone of upper Ordovician and compacted limestone of middle-lower Ordovician are favorable layers of this carbonate reservoir. However, the exploration job is rather difficult, because this carbonate reservoir is about 6500 meters underground in southwest of research area.Chapter V Reservoir prediction and evaluation of carbonate rock. Based on the research of carbonate reservoir of Ordovician and its structural characteristics, plane distribution feature of every formation of carbonate reservoir is studied systematically. Then, the reservoir and structure characteristics of carbonate reservoirs of Yingshan formation of lower Ordovician, of Yijianfang formation of middle Ordovician, of Lianglitage formation and Sangtamu formation of upper Ordovician are analyzed. Relying on unconventional seismic data processing of each reservoir and researching of reservoir prediction technique, the type of each reservoir is identified and the prospect of each reservoir is evaluated.Based on the analysis of the regional geology and tectonic background, there were the three main factors controlling the reservoir in Lianglitage formation of upper Ordovician, they were shale content, the developed degree of fractures and faults and the effect of ancient karsts, etc. According to the study of controlling factors of reservoir development and various abnormal congruent of the special seismic treatments, abnormality of the discontinued detection, strong amplitude change rate, strong amplitude areas, medium-low impedance areas were thought as the favorable areas of the advantage reservoirs in Lianglitage formation. The reservoir in the Yijianfang formation of median Ordovician was reef beach porosity and fracture-porosity types. According to the development of reef beach, karstification and fracture development, there were several kinds of reservoirs were evaluated as below, the first type of reservoir was mainly developed in the congruent position of the axis of the Akekule salient and karts gentle slope; the second type of reservoir was developed in the area where various abnormal congruent of the special seismic treatments, abnormality of the discontinued detection, strong amplitude change rate, strong amplitude were shown. The third type of reservoir were mainly contributed around the first reservoir and the second reservoir and they also belonged to the area of strong amplitude cluster and median-low impedance, the type of reservoir was mainly facture-type and a few hole-fracture type and karst-fracture type. According to the karstification and the fracture development, the type of reservoir in the Yingshan formation of lower Ordovician were classified to three types as below, the first type of reservoir was mainly developed in the congruent position of the axis of the Akekule salient and karts gentle slope; the second type of reservoir was mainly developed around of the Akekule uplift where abnormality of the discontinued detection, strong amplitude change rate, strong amplitude were shown; The third type of reservoir were mainly contributed around the first reservoir and the second reservoir and they also belonged to the area of strong amplitude cluster and median-low impedance, the type of reservoir was mainly facture-type and a few hole-fracture type and karst-fracture type.Finally, based on all above chapters, several conclusions and recognitions of geophysics response characteristics of carbonate reservoir of fracture-cavity type, the identifying model of fracture-cavity type carbonate rock, effective reservoir prediction technique, and the prediction of favorable carbonate reservoir zone in south of Tahe oilfield can be concluded.