Lithologic Reservoirs Theory And Methodology Research

With the national express economic growth, energy is demanded rapidly. To obtain the profitable business from oil exploration, stratigraphic trap has become dominant target of oil exploration. Because stratigraphic traps are of subtle and complexion, the system of theory and methodology for stratigraphic trap exploration has become important basic research in petroleum geology and effective means to avoid the risk for oil exploration. As an example, the petroleum exploration in Junggar basin is at the turn point from the stage of structure trap on paleo-uplift to the stage of stratigraphic trap on its slope. It is priority region of Jurassic stratigraphic trap exploration in their slops of the Xiayuan uplift and Zhongguai uplift that are braid delta front. So the study on the system of theory and methodology for exploring stratigraphic reservoir has been fulfilled in the dissertation.The integrative research methods are used in the study on stratigraphic trap, such as the combination of geology, seismology and loggings, analyzing 7 blocks 3D seismic data and more than 80 wells log curves and cuttings. A system of theory and methodology for exploring stratigraphic reservoir has been up built based on play and trap assessment. Many aspects of stratigraphic reservoir, including its definition, classification, basic geological, geophysical and technical research, identifying trap, play and trap assessment, characteristics and formation of stratigraphic reservoir, have been discussed. And more progress has been made.Under the guidance of sequence stratigraphy, the sequence boundary between Cretaceous and Jurassic system is reset by using seismic profiles and well data in Xiayan region. The new stratigraphic layer and play for stratigraphic reservoir are proposed. The dominant factors and data condition that affected stratigraphic trap are also analyzed. The East-Well Shinan 4 stratigraphic trap and The West-Well Guai 19 fault-stratigraphic trap have been identified and valued by the method based on trap assessment. The geological characteristic of Shinan 31 stratigraphic reservoir, Shinan 4 and Shinan 21 are anatomized based on reservoir analysis. The system of theory and methodology for exploring stratigraphic trap has been set up. The productions of the dissertation are as follows:The theory for exploring stratigraphic has been accepted as follows.The profitable reservoir is ascertained by compartmentalizing sequence stratigraphy. The types of stratigraphic reservoir are predicted by studying break slope. The prospecting area is outlined by plotting sedimentary system and facies and the abundant stratigraphic reservoir has enriched in fluvial-lacustrine transitional zones .The idea is guided by understanding oil system. The idea for exploring Jurassic stratigraphic reservoirs has been proposed based on the their Paleozoic source rock and sandstone enriched depression as stratigraphic reservoir, stratigraphic trap,sandstone bodies, reservoir rock and reservoir. The stratigraphic reservoir are dominated as follows, the series of stratigraphic reservoir related sedimentary is dominated by Max and earlier fluvial surfaces, stratigraphic reservoir is dominated by unconformity. The distribution, acreage and richness of stratigraphic reservoir are dominated by source faults, trap faults, reservoir faults.The methodology for exploring stratigraphic has been proposed as follows: The play assessment is studied under guidance of sequence stratigraphy sedimentary system and facies analysis, and the trap assessment is studied based on identifying trap, and the reliability and effectiveness of stratigraphic trap are estimated based on reliability of seismic data and petroleum system. The formation of stratigraphic reservoir is complex, and its dominant factors are unconformity, source faults, max higher fluvial surface and drainages system of petroleum. The stratigraphic traps are dominated by four lines such as pinch out, erosion, iso- thickness of reservoir, and iso-structure line, and four surfaces ceiling, bottom of reservoir, unconformity and fault. The contents of stratigraphic trap studies include data analysis of seismic and logging, stratigraphic trap play assessment, stratigraphic trap identification and stratigraphic trap formation mechanism. The accuracy of stratigraphic trap is affected in different stage of data gathering, processing, interpreting, impendence, mapping. It is emphasis that improving resolving power should be resolved in field stage and predicting petrology should be resolved in data processing stage.The sequence boundary between Jurassic and Cretaceous system is reclassified correctly in Xiayan region, because the stratigraphic trap has been discovered and enhanced the view.On the aspect of play assessment, the stratigraphic horizon (J2t0) and new play are proposed latterly, the newly stratigraphic layers (J2t0 Jzt3 J2x4) , including former Iayers(J2t2-. J2x2 J2S2) .are of stratigraphic trap. Seven stratigraphic trap plays, the Jidong play(the reservoir of J2t3N J2t2),the North-Well Shinan7 play(the reservoir of J2t2), the Jinan play(the reservoir of J2t3 J2t2 J2t1 J2t0), the Jibei play(the reservoir of J2t2 J2t J2t0), the northern of Sangequan sag play (the reservoir of J2t3 J2t2 J2t1 J2t0),the Shinanl3-Ji002(the reservoir of J1s1,), the northern of Shinan sag play (the reservoir of J2x3, J2x2 J2x1). Otherwise, in Zhongguai region, it is a prospecting region in its southern slope that some of the multiple horizons(the reservoir of J1b34 J1b1 3 J1S21 J2s31) are discovered of stratigraphic reservoirs.On the aspect of trap assessment, a variety of stratigraphic trap developed in Xianyan and Zhongguai region. There are uniform-orientation stratigraphic trap, converse-orientation stratigraphic trap, oblique-orientation stratigraphic trap, stratigraphic trap, left-fault stratigraphic trap, right-fault stratigraphic trap by intersecting sedimentary orientation with structure.On the aspect of reservoir character, the reservoir Shinan31 is regarded as structure-stratigraphic reservoir (J:to- Ktq) that is dominated by structure, lithology and stratigraphy. The Shinan4 (^2) & the Shinan21 (J2t2) are back-fence structure- stratigraphic reservoir by a narrow strait, which are different oil-water contact.The achievement of the research & its application has filled the blank of Junggar basin that the dream of discovering stratigraphic reservoir under the guideline of exploring stratigraphic trap has become true. The Shinan 31 Block structure-stratigraphic reservoir, which is regard as milestone of exploring stratigraphic reservoir in Junggar basin, has been discovered and 2119xlO4 tone geological reserve has been proved. The characteristics of the reservoir is considered as a structure-stratigraphic reservoir , which ceiling is of Cretaceous mudstone(K!q) , floor of Jurassic mudstone(J2t) , reservoir(J2t0) of Cretaceous conglomerates(Kiq) and Jurassic sandstone(J2to) that combined with unconformity(K/J).The theory and methodology for exploring stratigraphic reservoir has magnificent meanings of geological theory and practical application. So it might be applied in Junggar basin and the others.