Study on sequence stratigraphy of Lishu fault

Abstract

Under the guidance of sequence stratigraphy theory and method, the comprehensive utilization of seismic, logging, drilling and core data, set up the pear tree fault fault depression sequence stratigraphy framework. Pear tree will sag from top to bottom drill in quaternary, upper cretaceous qingshankou formation, lower cretaceous quantou formation, denglouku group, the city group, shahe, fire stone mountain group and basement, and focus on description of quantou formation, denglouku group, the city group, shahe, fire stone mountain group interface features. And the seven tree, Qin Gutun key stratigraphic classification and correlation in the study area for research. 1 Regional geological survey Pear sag is located in the southeast uplift area, songliao basin is a composite basin superimposed fault depression, east of tanlu fault zone, pear, gongzhuling across two city, covers an area of about 2300 km, mining area resources 360 million tons of oil equivalent, 205 opening of exploratory well, the whole sag found nine oil and gas fields, proven oil reserves of 44.3585 million tons, proven degree is 20.6%; Proven gas geological reserves of 19.341 billion square, the proven degree is 13.5%. Is divided into four secondary structural belt, the Northern Slope zone, steep slope zone, the central structural belt, west slope area in the east. Figure 1 pear trees in the study area 2 Sequence interface features Shahe subgroups (K1sh):fault sequence, the distribution is controlled by fault depression, stratigraphic thickness generally 600-1400 m, in the pear tree faulted the thickest of up to 2500 m. 2nd International Conference on Electrical, Computer Engineering and Electronics (ICECEE 2015) © 2015. The authors Published by Atlantis Press 1302 To mulberry fracture is bounded in the west and east, south overlap, to the north by denudation. The group at the bottom of the alluvial fan and braided river sedimentary, the upper plate to sub-sag in shore and shallow lake to half deep lake deep lake facies, basin around the development of fan delta, alluvial fan and limnetic facies. The group stratum layer in the development of important hydrocarbon source rocks in this area. City group(K1yc):belong to fault sequence, the group characteristics of stratigraphic distribution and shahe subgroups similar characteristics, to mulberry fracture is bounded in the west and east, south direction overlap, north raised by denudation, stratum thickness is usually 200-800 m. Sedimentary characteristics, its inheritance shahe subgroups period water scope to further expand, but water is a bit lighter. Main development of braided river delta or alluvial fan, fan delta, littoral and shallow lake, half deep lake-deep lake deposits, such as high quality hydrocarbon source rocks, also can form high quality reservoir, often form since the author classifies the type accumulation combination. Denglouku group (K1d):belong to fault sequence, stratigraphic distribution features inherited battalion city group, the thickness of the 100-1500 m, lithology of light gray, gray, beige, gray sandstone, mudstone and grey, glutenite, unconformable contact with the overlying quantou group, development of sedimentary facies have shore shallow lake and deep lake half deep lake, fan delta deposit, etc. Quantou group (K1q):period of quantou formation in basin evolution into depression stage, no longer restricted by fault basin, are widely distributed. The sedimentary strata in the southern songliao basin are stable distribution, formation thickness usually is 500-1800 m. Lithology is given priority to with oxidation and tonal mudstone and sandstone and glutenite, dominant in river deposits, followed by flood plain, shore and shallow lake sedimentary, delta and its stable distribution of small. 3 The sequence stratigraphic framework analysis 3.1 The north-south direction stratigraphic framework analysis Around in the seismic section the reflection layer interface structure, logging and logging data has obvious feature. Shahe son of stone mountain fire at the bottom of the group, or basal surface of the basin, which is a Mesozoic strata, is formed by uplift period of basin tectonic activities area truncation unconformable surface, corresponding to the seismic reflection interface T5, equivalent to the Jurassic bottom reflection interface. Reflector above show the onlap phenomenon, basal generally strong reflection energy, lower for clutter weak reflection or layered weak reflection. Under interface is basement metamorphic rock, mudstone cover directly above the basement metamorphic rocks, the surface of discontinuity generally represents the sedimentary environment mutation, on logging curves at the same time also have obvious response (figure2). Figure2 sequence region and even the well seismic profiles Figure2 sequence region and even the well seismic profiles