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The southern margin of the Ordos Basin Yanchang Coupling Relationship between source and diagenetic

Author: WanYouLi
Tutor: ZhangShaoZuo
School: Chengdu University of Technology
Course: Mineral prospecting and exploration
Keywords: Ordos Basin Source analysis Reservoir Characteristics Diagenesis Coupling relationship
CLC: P618.13
Type: Master's thesis
Year: 2011
Downloads: 192
Quote: 2
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Abstract

Ordos Basin is located in the region of the eastern lands constructed by the eastern and western construct multi-stage, repeated alternating tension and compression effect, the formation of unconformity bounded multi-tectonic regime, many evolutionary stages, and more depositional systems, multi-composite prototype basin superimposed basins in China's administrative divisions across Shaanxi, Gansu, Ningxia, Inner Mongolia, Shanxi and five provinces, an area of about 37 × 10 ~ 4km ~ 2. Tectonic units can be divided into Yimeng uplift, uplift Weibei West foreland thrust belt, Tianhuan Depression, northern slopes and Jinxi flexure zone, where a huge area of northern slope, constituted by Triassic basin The main areas of petroleum exploration. After decades of Ordos Basin, exploration and development of oil fields have been discovered and put into display: Mesozoic strata within the basin thickness and wide distribution, mainly, reservoir rocks of Late Triassic Yanchang, where long seven oil group length 45 oil group developed a large segment dark mudstone, semi-deep lake - deep lake sediments; Chang 6 and Chang 8 oil group development in sandstone reservoirs; reservoir sand bodies are mainly northeast gentle river delta system and steep area Southwest braided delta system, developed in the northwestern and southern small fan-delta system, the semi-deep lake - part of the regional development of deepwater turbidite fan deposits; stratigraphic and stratigraphic traps constitute the Triassic Yanchang hydrocarbon accumulation in the body. Late Triassic in Ordos Basin Yanchang basin sedimentary fill records generated, intermittent oscillatory lake into Lake retreat and the demise of the evolutionary history of the rise and fall. Source analysis study of sedimentary basins in the extended period is more than one major river catchment basin, the ancient water main 190 ° ~ 250 ° east and west 50 ° ~ 65 ° to the two mainstream, outcrop in the northwestern margin of the basin flow the basic 105 ° ~ 135 ° and south direction, north direction south of the basin of water streaming; light and heavy mineral studies and REE REE patterns also show characteristic Late Triassic sedimentary basins main source of direction for the North East SW direction and provenance, there is also the northwest provenance provenance and South, but the South is not the scope of provenance. Combined study basin boundary determination, to be able to extend the Late Triassic sedimentary rock material source provided the northeast direction Yinshan Oldland Wulashan Group, Jining Group, northwest of the ancient land Alashan Alashan base, southwest from Longxi ancient land, Qinling - a senior Qilian ancient land and granite rocks, controlled by the corresponding growth in the interior of the basin formed a large northeastern slope composite river delta system, Northwestern fan delta depositional system, large steep southwest composite braided river delta and fan-delta system. Diagenesis: the Yanchang sandstone experienced early diagenetic compaction and cementation, late diagenetic dissolution period and metasomatism. Early diagenetic compaction and cementation cause sand reservoir performance degradation and dissolution metasomatism improved sand pore structure and reservoir performance, but overall Yanchang sandstone still has extremely low porosity and permeability characteristics . Clastic reservoir porosity and burial depth is both a function of secondary porosity, and is subject to the conditions and sedimentary provenance environmental control sediment composition and structure, controlled by tectonic movement and burial history of sedimentary detritus, hydrodynamic conditions, characteristics and evolution of pore fluid phase geothermal field, and reservoir rock within the system related to the deposition of organic matter and clay mineral diagenesis and a series of related factors together result. Provenance and depositional environmental control sediment composition and structure, through burial, diagenesis, Yanchang sandstone because of different provenance and depositional environments of the sedimentary system diagenesis also has differences, by the Yinshan Oldland material source control and development of the northeast Large gentle slope depositional systems feldspar and mica sand content, compaction strong laumontite cementation cementation of this area is the main feature of feldspar dissolution stage dissolution occurs mainly in the delta plain distributary channel sand bodies, the hydrocarbon source rocks generated when organic acids from the center of the basin to the northeast along the right edge of the migration time for dissolution Laumontitization form different degrees of erosion zone, feldspar dissolution and dissolution Laumontite greatly improved reservoir performance. Southwestern and southern sand sand sand than in the Northeast, the quartz content is high, rigid particles on the supporting role of the overlying strata stronger, but the overburden is thicker than the multi-northeast, as well as a large number of phyllite lithic, so Southwestern compaction are more intense, early diagenetic chlorite rims formed on the primary porosity sandstone headquarters has a protective effect. By Northwest provenance grade metamorphic, volcanic sedimentary system control Chang 6 oil reservoir development than long eight narrow lot, shallow rocks in the compaction is extremely easy to form a false heteroaryl being blocked pores, so rigid particles of quartz How much and reservoir properties have a very good correlation.

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