1、1Zhunzhong Area Qingshui River Group SequenceSedimentary Characteristics and ModelsAbstract： Zhunzhong area Qingshui River group has top and bottom boundaries， which are not clear，and research on the evolution of the lack in sequence stratigraphic framework of deposition and on the reservoir sand bo
2、dy types do not have a clear understanding problem.In seismic interpretation， core description and based on the analysis of the related test，combining with the mud logging and well logging data，for the redefinition of Qingshui River group on the top and bottom boundaries，it identifies 6 time signifi
3、cance of sequence boundary，taking Qingshui River group can be divided into 2 sequences， 5 system tracts；clear and definite the study area mainly developed delta lacustrine depositional system，which can be further divided into the delta front subfacies， beach bar facies and semi deep lake subfacies.
4、It takes an analysis on the sedimentary characteristics and distribution rules of different types，and it controls effect of topography and hydrodynamic conditions on deposition system，and then puts forward the corresponding sedimentary patterns. 2Keywords： Zhunzhong Area；Qingshui River Group；Sequenc
5、e stratigraphy；Sedimentary characteristics；Sedimentary Model； Introduction Through preliminary exploration work，in the Zhunzhong area， it has found oil and gas fields in Moxizhuang， Shawodi oilfield， sign Sha Cun oilfield and into the oil and gas fields etc.， the Cretaceous is the main reservoir， th
6、ree level of reserves of 100 million tons.Study of the predecessor to the Cretaceous Qingshui River formation sedimentary environment and characteristics： Gu Yunfei （2003 years） that the Qingshui River formation deposited，basin is a Cretaceous peneplain formation stages of basin；Si Chunsong （2005 ye
7、ars） Qingshui River formation can be divided into 1 long-term base level cycles， 2 middle term base level cycles and 5 short-term base level cycles.But there still exist in Qingshui River group of top and bottom boundaries are not clear，research on the evolution of the lack of sedimentary sequence f
8、ramework and on the reservoir sand body types understanding degree is not deep problem. In this paper， based on the sequence stratigraphy theory，through the seismic， drilling， core， logging system， analysis of the sequence stratigraphy of Qingshui 3River group of Cretaceous in Zhunzhong area，discuss
9、es the types of facies in sequence stratigraphic framework of the main sedimentary， distribution and evolution model，the relationship of sand bodies in various reservoir，the symbiotic laws and control factors，for the oilfield production target， which has the vital significance. 1.Tectonic background
10、 The study area is located in the hinterland of Junggar basin， the central depression，north of Ba bentazone， south of the Northern Tianshan thrust fault fold belt，things were in Chepaizi uplift and Mo North projection is bounded（Figure 1）.Including Sinopec registered in 1 and two in 3 exploration bl
11、ocks Analysis of geological tectonic evolution in the Zhunzhong area，the Jurassic sedimentary relatively stable，in the late Jurassic due to influence of Yanshan main episodic tectonic activity，the west uplift，the eastern settlement，in Che Mo low amplitude anticline structure at the top of the upper
12、Jurassic and Middle Jurassic Xishanyao Formation is eroded away，regional strata denudation formed between Jurassic and Cretaceous near 30 Ma surface 1-2 Figure 1 tectonic zoning map in the Zhunzhong area 2.Sequence stratigraphic characteristics 4To establish the sequence stratigraphic framework of c
13、omplete，accurately on the stratigraphic division is the basis for the study of sedimentary characteristics of the.The author in a detailed understanding of based on the sedimentary characteristics of the，application of Vail classic sequence stratigraphy theory，through the division of seismic sequenc
14、e and the rock electricity sequence features，combined with the mudstone sonic， wavelet energy spectrum analysis method of sequence boundary identification，stratigraphic framework for the study area. （1）The earthquake sequence characteristics In the study area tracking explains 4 reflection to the sa
15、me axis，bottom-up named of SB1、MFS、SB2 and SB3 （Figure 2）.Adjacent of the two event keeps basically parallel，strata thickness， is a typical parallel， sub parallel reflection structure. Truncation is referred to the original strata inclined in the horizontal direction angle intersection，which genesis
16、 and tectonic movements， periodic exposure；In seismic profile， erosion truncation regional representative discontinuous3.In the study area， village 7 well near the SB1 reflection axis under visible truncation phenomenon，for the Jurassic / 5Cretaceous regional angular unconformity surface reflection；
17、the local area is also visible SB3 reflection axis is overlying formation truncation. Figure 2 - North and south of Qingshui River group in the Zhunzhong area to the seismic reflection characteristics （2）Sequence characteristics of rock electricals Compared with the seismic data，logging data not onl
18、y has higher vertical resolution，and analysis can be performed for all the wells formation，combined with the extraction of lithologic information logging， core and outcrop data，research on precise quantification and transverse comparison of stratum.At present electric Prorperties analysis has been w
19、idely applied in sequence stratigraphy and Sedimentology.4 Based on the synthetic seismogram calibration method，The seismic information combining with logging， logging data，rock electrical feature recognition of each seismic sequence interface，in addition， the other two have the time significance of
20、 interface of FFS1 and FFS2. Figure 3 in the Zhunzhong area of Qingshui River group of sequence stratigraphy （3）Other features In addition to seismic sequence analysis characteristics 6and rock electrical sequence features，this paper，research of uses the time difference and wavelet mudstone acoustic
21、 spectrum analysis method and so on characteristics of sequence.5 （4）Sequence stratigraphic framework Application of Vail sequence stratigraphy theory，the above various sequence features and regional geological data analysis，sequence stratigraphic framework in the Zhunzhong area of Qingshui River gr
22、oup6.The Qingshui River group was divided into sequence 1 and sequence 2： Sequence 1 complete contains lowstand， transgressive systems tract and highstand of 3 system tracts，but the sequence SQ2 top highstand system tract denudation，contains only the lowstand and transgressive domain of two domain s
23、ystem （Figure 3） Knowledge of previous different， this research believes that the Qingshui River group in the bottom of the Jurassic Cretaceous regional angular unconformity boundary marker，it identify the main application of seismic data truncation phenomenon，with the combination of well and seismi
24、c method to Identification；While the top by mudstone color from grey mutation to red brown to mark the boundary，to identify the main according to the well logging data， the upper part of the red mudstone layer under the Hutubi group. 73.The main types of sedimentary facies Through to comprehensive a
25、nalysis of mudstone color， sedimentary structure and logging curve of various phase marks in the Qingshui River group rock types in the area of each well drilled7， we think in the Zhunzhong area of Qingshui River group developed delta lake sedimentary system，Divided into delta， beach bar and semi de
26、ep lake ， 3 kinds of main facies. （1）Delta front subfacies Delta front subfacies is the main research area of delta sedimentary，it is the sand body is the most developed sedimentary facies belt，the sedimentary range is very extensive.It can be further divided into underwater distributary channel and
27、 delta front sheet sand that two microfacies. Underwater distributary channel is the land branch channel underwater extension，due to the lake in the extension process，the river widens， slow flow velocity， sediment accumulation rate increases and the formation of.Sediment grain size is relatively coa
28、rse， thick layer of gravel sandstone and fine sandstone （Table 1） ，separation of grinding medium.The bottom visible erosion filling structure （Figure 4-A） ， mud gravel layer （Fig. 4-b， 4-C） and mudstone rip up clasts 8（Figure 4-D） ，development of trough cross bedding， wedge shaped cross bedding and
29、parallel bedding bedding types. Front sheet sand， is a product of the underwater distributary channel sand， mouth bar sand lake waves and longshore currents transformation.The thickness of single layer thin sand body，the average thickness of 2-3 meters，the powder sandstone and argillaceous siltstone
30、， mudstone is the main features of the lithologic association，sorting， round in shape.Common wavy composite bedding sandstone （Figure 4-e） ， the wave into the sand bedding （Figure 4-f） sedimentary structures.Well logging curve showed knife， finger like features.The probability curves of grain size d
31、ue to lack of rolling components，in two hop a suspension type mostly， reflects the interaction of river and lake waves. （2）Beach bar facies Developed in the shallow part of beach bar，the main subject of wave and lake current and transportation and redeposition formed.Since the sand body after handli
32、ng and screening of long distance，the grain size is fine， lithology is mainly composed of silty mudstone and siltstone， sorting and roundness.By the modification effect of wave strong，common washing bedding （ Figure 4-g） ，the plane peel lineation 9structure development，also visible more bioturbation
33、 structures （Fig. 4-h）.Well logging curve in reverse order characteristics，the probability curves of grain size as jump a suspended two segment for the. （3）Semi deep lake subfacies Located below the normal wave base， the scope of the storm wave base，soil of weak reduction in hypoxia -reduction envir
34、onment，sediment is mainly affected by the lake flow and storm wave action.The lithology of thick layer grayish black mudstone，containing a small amount of siltstone， developed horizontal bedding （Figure 4-i） and fine wavy bedding.fossil plankton rich，and the preservation of good， high organic matter
35、 content.Well logging curve is the main performance for the high gamma characteristics. yong 9 well，5862m，Erosion surface；b.yong 2 well，5971.4m，Gravel layer； c.yong 9 well，5862m，boulder clay；d.village4 well，4020.3m，Mudstone rip chip；e.sign 3 well，4968m，Climbing bedding；f.yong 2 well，5375m，Wave rippl
36、e cross beddings；g. Village 4 well， 4016.9m， wash bedding； h. Sign 3 well ，4966m，bioturbation；i.yong9well ，5760m，horizontal bedding. 4.Sedimentary facies distribution 10Sequence 1 deposition，Lowstand system tract developed only in the limited area of the eastern part of the study area，range from nor
37、theast to South shop well area near Mo Yong 7 well，while the west is in Sha 3 well， sign 102 well and yong 8 well is the boundary. Compared with the sequence 1 lowstand system tract，sequence 2 position system tract of underwater distributary channel range is relatively small，while the front sheet sa
38、nd range enlarge.This is because the compensatory deposition after sequence 1 after，The study area of terrain change relatively flat，at the same time the Lake wave effect is more strong.Transgressive system tract is still in the lake facies mudstone facies，two beach dam development in village 6 well
39、 and yong 8 well. 5.Sedimentary model Joint control the deposition of Qingshui River formation in the Zhunzhong area evolution process is mainly controlled by the palaeogeomorphology differences and hydrodynamic condition.On the basis of sedimentary model is established in the Zhunzhong area of Qingshui River group. Affected by the Yanshan main episodic tectonic movement，the Cretaceous uplift and denudation，in the northeast part of the study area formed a limited area of
