The Accumulation Research Of Lithology And Structural-lithologic Reservoirs In The Western Slope Of The Northern Songliao Basin

The western slope of the northern Songliao Basin(the region of the west axis of Qijia- Gulong sag) which is the lower levels of Daqing oilfield exploration blocks one that contains the western of Qijia- Gulong area, Longhupao- Daan terraces, Taikang uplift zone, West zone overlap. The exploration area is 27299km2, near the deep depression of Gulong mature source rocks area, with good oil sources condition, the long-term development of the monoclinic structure which inherited fracture relatively undeveloped. The area has 623 exploration wells, contains 380 industrial oil and gas wells, the three grade oil geological reserves 4.67 × 108 t, the three geade natural gas geological reserves 79.5 × 108m3. The area has been found to construct reservoir types, lithology based, currently only achieved a breakthrough in Saertu oil reserves, that still have huge exploration potential. Some non-structural development zone also had oil and gas exploration wells, showed heralded lithologic reservoir exploration in the area and had a greater prospect. Oil resources in the area is 11.62 ~ 16.56 × 108 t, but the difference between the larger oil gas exploration and discovery resources is large. Geological background and forming conditions showed overlap in the western belt and Longhupao terraces slope break belt with the formation of lithologic traps, stratigraphic and structural traps cover- lithologic trap conditions in northern Songliao Basin shallow depth exploration prospects in the region, and the future exploration of Daqing Oilfield main goal zone. In addition, the development of western slope unconformity, unconformity block stratigraphic reservoirs have favorable conditions to form. Based on the sequence stratigraphy theory, the establishment of the study area, other stratigraphic framework, within this framework, the sequence stratigraphy and sedimentology, tectonics combined analysis of base-level cycles evolution of sedimentary systems the constitution, the interfacial properties of sedimentary evolution and configuration of the relationship between the body and explore palaeogeomorphology slope break with developmental characteristics and sand control principle, to carry out the western slope lithologic and stratigraphic traps in the formation conditions and distribution of research, which is to find favorable lithology trap, to open a new situation western slope oil gas exploration and had an important practical significance.This study based on previous research on the full investigation core, logging, seismic data analysis, comprehensive utilization, through combination of well, seismic contrastive analysis, palaeo geomorphology restoration, hydrocarbon potential analysis and other technical means to establish of high-frequency sequence stratigraphic framework, analyzes the distribution characteristics of the sedimentary system and sequence stratigraphic sand, at the same time establish well and seismic recognition template of all kinds of sedimentary microfacies and sedimentary bodies, evaluation of hydrocarbon source rocks and oil source correlation analysis work through the exploratory sampling, analysis of oil, gas reservoir forming conditions, predicted the development characteristics of different horizons of various traps and favorable target zones, finally pointed out the exploration area in the west slope. The main achievements and innovations as follows:Firstly, in the west slope region established Quantou formation of lower Nenjiang formation the high resolution sequence stratigraphic framework. Longitudinally into 9 the third order sequence, 16 the forth level sequence, 54 fifth level sequence. Characterization of the plane distribution of 54 fifth level sequence of sedimentary microfacies, the sedimentary environment of recovery of Quantou formation in west slope of Nenjiang group of 54 fifth order sequence, laid the foundation of reservoir research for oil and gas accumulation. Establishment the gravity flow channel, sublacustrine, lacustrine limestone, mouth bar, sheet sand, distributary channel, far sand dam sedimentary body seismic reflection feature recognition template, directly guide to the west slope of sedimentary microfacies and favorable geological target exploration.The second, recognizing the western slope of Qingshankou-Yaojia group had two level slope belt, vertical the slope belt gradually become slowly, the features is north gentle and south steep. The first slope breaks of Qingshankou group controlled the coquina and delta front facies, the second slope breaks controlled turbidite deposition; the second slope break in Yaojia group controled the development of the delta front deposition. The main development of lithologic trap, stratigraphic trap and structural-lithologic traps, including Quantou group consists 60 lithologic trap identification, area 2312km2; Qingshankou group identified 698 traps, area 6826km2; Yaojia group identified 35 lithologic traps, area 1367km2. The most of favorable traps are lithologic traps, mainly distributed in Taikang-Longhupao region.The third was further clarify the oil-gas source of Saertu and Gaotaizi oil layer in the Taikang uplift zone, realized the main source rock of Saertu oil layer were in Qin two and three section source in Qijia-Gulong area, there will be localed source rock contribution, the main source of Gaotaizi reservoir oil come from Qijia Gulong area source rock.Source rocks in the local youth section of the main sources of green section of the oil, which belongs to the self storage type oil and gas reservoirs. Analysis of oil and gas into the main controlling factors of reservoir clear Meilisi fault and advanced T02 activities controlled the structural lithologic oil and gas reservoir distribution in plane.The forth was found in the deep lake facies zone of gravity flow deposits and shore shallow lake two big exploration field sedimentary biogenic limestone facies, four types of target, put forward five well targets. Gravity flow deposits including Yingtai-Talaha area which was the one and two segment of Qingshankou group slope fan and sublacustrine fan, Bayanchagan and surrounding areas tender a gravity flow channel and sublacustrine fan. Shore shallow lake facies zone, biological limestone deposition, including two section of lake facies developed area of shelly limestone, shelly siltstone, shelly oolitic limestone and Ostracoda limestone types. This discovery of new exploration types were the favorable targets for forming lithologic traps.This study recovered the evolution of the western slope deposition, more objectively analysized different sedimentary period of source reservoir cap space allocation relations, laid a solid foundation for the study on reservoir in the western slope.To further clarify the Taikang uplift zone of Saertu and Gaotaizi reservoir oil and gas sources, exploration strategy for west slope provide a new inspiration. Establishment of the gravity flow channel, sublacustrine fan, lacustrine limestone, mouth bar, sheet sand, distributary channel and other 7 kinds of different sedimentary bodies recognition template, guided the western slope of favorable sedimentary microfacies and sedimentary geological exploration. This study provides the favorable target for well deployment provided a theoretical basis, project templates established sedimentary bodies recognition and favorable targets, laid the theoretical foundation for the development of other strata of Songliao Basin seismic sedimentology and well design, got a good effect in the northern Songliao Basin oil and gas exploration.