characteristic of ancient geographic lithofacies in bach ho basin

INTRODUCTION Target : Target of topic to to clarify characteristics of sedimentary facies, sandstone lithology of the oligocene sedimentary in bach họ area of cuu long basin thereby creating the basis for the study characteristics of source rock, reserver rock and seal rock Tasks of research subjects Characterize oligocene sedimentary facies in the region bach ho - cuu long and composition relationship to each other Study characteristics sandstone lithology, sedimentary parameters thereby create conditions assessment of rock collector The content of the research includes the following sections Introduction Chapter I characteristics of regional geology Chapter II history of research and research methods Chapter III characteristic of ancient geographic lithofacies in bach ho basin Chapter IV evaluating the potential petroleum based on oligocene sedimentary environment research Conclusion CHAPTER I CHARACTERISTICS OF REGIONAL GEOLOGY 1.1 STRATIGRAPHY Cuu Long basin is located in the southeast shelf of Vietnam which has a large oval structure terrian and subsidenced in the Cenozoic as well as surrounded by the high Mesozoic zone This sedimentary basin is not lagre (about 200.000km2) To the west of the basin is surrounded by shoreline from Ca Na - Vung Tau to Ca Mau; South and Southeast separated from the Nam Con Son basin is the uplift of underground zone Con Son, run along the existing islands like Hon Khoai, Hon Trung - Con Son Sediment inside the basin consists mainly of terrigenous components Coarse and fine aged Eocene Oligocene to early Pliocene – Quaternary Kainozoic sediments thickest reaches nearly 7,000m Current seabed depth not exceeding 50 m, as favorable conditions for research and exploration and exploitation of oil and gas 1.1.1 Tertiary stratigraphy Tertiary strata in the Cuu Long basin is divided into stratigraphic levels Eocene, Oligocene Lower, Upper Oligocene, Lower Miocene, Middle Miocene, Miocene, Pliocene - Quaternary (the formation of Ca Coi, Tra Cu, Tra Tan, White tiger, Con Son, Dong Nai and Sea) 1.1.1.1 Early Oligocene - Tra Cu Formation (E31tc) Tra Cu Formation is alternating between gravel, sandstone with clay powder layer containing pebbles, grit and gravel Cobbles offers various lithological composition, mainly andesite and granite rock Early Oligocene Tra Cu Formation formed in the area of environmental conditions: floods, rivers, lakes, bays Tra Cu Formation thickness changed from 100 to 500 meters (measured in wells) in the arch lift, while in the valley reaches over 1,000m According to seismic data, expressed in Formation seismic episode which Vietsovpetro joint venture company known as collective E; corresponding bottom seismic episode very little differentiation, continuous low level, relatively large amplitude, low frequency, there is no rule subclass, often covered unconformity directly above the basement rocks In sedimentary formations of ancient ruins born very poor; only few pollen spores: Magnastriatites howardi, Verrucatosporites, Triletes, Pinuspollenites, Oculopollis Eocene - Oligocene, determined by Oculopollis (LAD in late Eocene) and Magnastriatites howardi (FAD in late Eocene) However, based on stratigraphic relationships, Tra Cu Formation Oliocen early age by lying on the Ca Cối Formation (Eocene) 1.1.1.2 Late Oligocene - Tra Tan Formation (E32tt) Late Oligocene - Tra Tan Formation sandstones include small to medium gray grain white, carbonate cement, moving to the top with multiple layers of siltstone, claystone brown and black, alternating thin layers of coal, place contains glauconite Formation sediments rich in organic materials Sapropel amorphous forms, organic material forms arise in conditions without oxygen tank This property Morley called "General Sapropel" while analyzing wells in Lot 15 Also facing freshwater algae as Pediastrum, Bosidinia The altered rocks in the late phase Catagen Tra Tan Formation widely distributed than Tra Cu Formation thickness and relatively large changes in different areas of the basin Tra Tan Formation sediments have alternated between claystone (accounting for 4070% of the sections, especially in the northeast lots of basin), siltstone, sandstone, and in many places Tra Tan Formation environment formed in rivers, deltas and lakes coastal wetlands - the shallow sea bays Tra Tan Formation thickness observations wells ranged from 400 to 800m, while in the valley can reach 1,500 meters 1.1.1.3 Early Miocene - Bạch Hổ Formation (N11bh) Early Miocene sediments - Bạch Hổ Formation wells described in BH1, from 2037 to 2.960m depth Sediments include thin-bedded sandstones, siltstones, dark gray, gray-green (bottom) alternating layers of sandstone siltstone gray to brown; gray-brown clay and claystone gradually to graygreen, homogeneous (above), containing fossilized marine animals should Rotalia group called clay Rotalid (mainly ammonia size 1/10 mm) The thickness of the formation varies from 400 to 1000m Throughout the Cuu Long, Bạch Hổ formations developed quite extensively The lower section consists of sandstone of different grain size alternating siltstone and claystone, some areas containing debris in energy conditions vary sharply from region to region Above, in most developed place claystone, contains many shallow marine fossils Rotalia alternating layers of siltstone, sandstone layer at a small grain, gray contain glauconite Generally, formations are formed in the river environment, estuaries, coastal wetlands and shallow sea with sea ascending trend going from the edge of the basin southwest through the central portion to the basin area to the northeast The abundant fossils contained in sedimentary include: Nanoplankton and Foraminifera: Magnastriatites howardi, Florschuetzia levipoli, Rotalia, Pediastrum - Botryococcus, and dinoflagellates: Cribroperidinum, Apteodinium given early Miocene age formations 1.1.1.4 Middle Miocene - Con Son Formation (N12cs) Middle Miocene sediments - Con Son Formation with sedimentary materials include quartz sandstone, small grain are predominantly coarsegrained mix of grades 1-2 choose from average to poor, clay and cement is less carbonate , above have little alternating layers of clay and silty brown, gray and coal lenses The thickness of the formation varies from 650 to 1000m Con Son Formation extensive distribution throughout the Cuu Long basin Sedimentary environments of formations moved from rivers, deltas, coastal marshes to shallow sea In the sediments of Con Son has discovered pollen and spores of fossil foraminifera and Nannoplankton including Florschuetzia meridionalis, Lepidocyclina (TF2), Orbulina universa (N9), Calcidiscus marcintyrei (NN4NN19) to Middle Miocene age 1.1.1.5 Late Miocene - Dong Nai Formation (N13dn) Late Miocene sediments - Dong Nai Formation sedimentary materials include the layers, sandstone small to medium grain, moving gradually up the alternating sandstone siltstone, claystone and coal There where pyrites and glauconite sandstones contain The thickness of the formation varies from 500 to 700m Dong Nai Formation is present throughout the Cuu Long Basin, including sedimentary environment formed in rivers, deltas, coastal marshes and shallow sea Sedimentary rock are in the early stages, new rock mounted only weak or even loose and easy to dissolve in water In Dong Nai formations found many fossils of foraminifera, Nannoplankton Stenochlaena laurifolia, along with the abundance of walls such as Florschuetzia levipoli types, Fl Meridionalis, Rhizophora, Carya, Pinus, Dacrydium, Acrostichum and middle Neogloboquadrina acostaensis (N16), Nano Discoater quinqueramus (NN11) Late Miocene age 1.1.1.6 Late Miocene - Biển Đông Formation (N2 PTT) Formation can be divided into two parts - the lower part is rough quartz sand, gray and white contain foraminifera fossils Operculina heading (to the Pliocene) and part on the unconsolidated Quaternary sediments The thickness of the formation varies from 200 to 500m Bien Đong Formation (lower section) distributed across the Cuu Long basin-wide development in the region, mainly in the form of environmental and shallow marine estuary with sediment still weak under tension In sediments (under low part) Bien Dong formations found abundant fossils include pollen spores Dacrydium, Stenochlaena laurifolia and Foram Sphaeroidinella subdehiscens (N19), Nano Discoaster intercalcaris (NN12) given Pliocene age STRUCTURAL AND TECTONIC 1.2.1 Location tectonic of Cuu Long basin Cưu Long sedimentary basins located in the southern - southeast of Vietnam Sea, is a sedimentary basin with a portion located on land within the area of the Mekong River mouth, and most of the area is located on the continental shelf of Vietnam Cuu Long basin-shaped "oval" is located along the coast of Binh Thuan Vung Tau-, this is an internal continental sedimentary basin typically enclosed in Vietnam continental shelf basin structures developed in the NE - SW, strong subsidence in Kainozoi and filled by sediments from rough to smooth Eocene aged In view of the stratigraphic formations set includes the complete set of complex: Eocene, Oligocene lower on Oligocene, Miocene lower, middle Miocene, Miocene on, Pliocene - Quaternary Currently, the Cuu Long basin bordered the mainland to the northwest, separated from the Nam Con Son basin by Con Son uplift, the uplift southwest and northeast Korat-'s Natuna shear zone separates Tuy Hoa Phu Khanh basin 1.2.2 Characteristics tectonic faults The study area was the complicated and is cleaved into different blocks by different fault systems Based on the activity of the faults can divide them out four main fault system + East - Northeast / West - Southwest System + East - Southeast / West - Northwest System + Meridian system, + Parallel system 1.2.2.1 East - Northeast / West - Southwest System Fault systems include faulting along the two groups but have different geographical location, age, shape, amplitude displacement, angle and intensity plugging operations as well as the role they have on the formation of oil in the nail itself is also different East – Northeast reverse fault system This fault system is located in the north-west wing of the Bach Ho area They are formed later than the faults along the southeast side of Bach Ho These are overthrust fault is born into by local compression phase occurring in late Oligocene close, they continue to operate during the late Oligocene to early Miocene early, demonstrate their activities while longer exists in until finished off local compression Given the strong compression that basement in Bach Ho block smashed the system creates fissures crisscrossing dense Because of time formed after the early Oligocene sediments should these cracks are not filled by the debris so they have created a massive hole and connected together makes the permeability increase and facilitate movement and hydrocarbon accumulation in the empty space there Conveniently fault systems East - Northeast / West - Southwest System along the side of the East – Northeast Most of the faults of this system have deep roots and was born into a foundation during the late Mesozoic smashed, some of them have nonstop activities from the majority of the foundation still others continue during rifting activity with other faults have been born into during rifting Late Oligocene to near the end, most of the faults in this region of ceased operations 1.2.2.2 East - Southeast / West - Northwest System This fault system developed mainly in the central part of the Cuu Long Basin area The main fault systems were split Cuu Long out of various blocks The success of they born in the early stages of rifting period and continue to operate during a break there and also end late Oligocene Amplitude shift of this fault system is smaller than the amplitude of the fault system East - Northeast / West - Southwest System and only about 200 300m 1.2.2.3 Meridian system The system has the meridian fault is detected in an area north and central part The active faults primarily on early stage rifting and then rest, activity, their role is only further complicated the internal structure of the sedimentary basin 1.1.2.4 Parallel system This fault system developed primarily on the area of Rong and in the entire area west Bach Ho tropical depressions They are born into early and continue operating in the period rifting and also at the end a break operations late Oligocene These two faults have considerable length, with small amplitude displacement (200 - 500m) 1.2.2.5 The role is created by the main fault systems Full featured synthesis of main fault systems in the Cuu Long Basin, as well as integration with document tectonic stress field nearby, Cuu Long basin is believed to have directly influenced by two field-effect main interest is created, namely: The maximum compression under the East - Southeast / West Northwest System and maximum extension under the East - Northeast / West - Southwest System This tectonic stress field took place in the period from late Eocene to Oligocene, Cuu Long was split open maximized The maximum compression under the meridian and maximum extension according to the latitude This phase happened in the period from early Miocene until today The consequences of this tectonic stress field corresponds to the period after the rifting of the tank and the system creates reverse faults, overthrust accompanying slide translate to widespread development in the whole study area 1.3 LAYERED STRUCTURE OF CUU LONG BASIN According to seismic data - geological and drilling material and other documents already, structural geology study area can be divided into twostory main structure follows: • Structure section under (A) Part structure under include Pre-Kainozoi formations with rocks and that the heterogeneity of the lithological composition of rocks and colorful They include granite, biotite, granitoid, granodiorite and many places are experiencing both riolit and metamorphic rocks According to the analysis of isotopic radioactivity was identified as the Jurassic, Cretaceous of Da Lat zone - Cambodia These wells have encountered basement rocks weathered and cracked foundation on the raised zone is mainly and sometimes granite or granodiorite and sometimes both metamorphic rocks • Structure section upper (B) Part textured include Cenozoic age from Eocene to Quaternary They cover the unconformity on under part of the structure Part of this structure is divided into three sub-sections of different structures The division was based on lithological characteristics, history and sedimentation environment The boundary between the sublayer structure is the unconformity surface, marking the sedimentary cycles associated with the phase corresponding tectonic activi 10 Eocen 0-600 Flood area, river, lake Cà Cối Foundation before Kanozoi Under(A) 30 CHAPTER III CHARACTERISTIC OF ANCIENT GEOGRAPHIC LITHOFACIES IN BACH HO BASIN This is the beginning stage of the history of formation and evolution in the Cenozoic sedimentary basin Bach Ho mining areas On cross restored geological structures can be observed a vivid picture of the "dawn" recorded the imprint destroyed by continental crust 10 active fault systems oriented NE - SW created composed of zones: the central uplift, subsidence northwest zone and rift zones, subsidence southeast During this period the central uplift always acted as erosion areas provide material for two basins mainland northwest and southeast under the sedimentary Sediment thickness increases from the center to the edge of the flanks due to falling grades fault systems (Bascule) and creating a single foundation inclined structure but clearly differentiated Study characteristics and sedimentary lithofacies - ancient geography in the first development stage basin is a very important mission Because of information received from petrographic research and analyzes lack adequate facies has created controversy and different perceptions of sedimentary environment in early Oligocene stage Thus, leading to misperceptions about sequence stratigraphic, especially identification of sedimentary region system is deceptive The idea that only early Oligocene formations in the continental environment includes alluvial and freshwater lakes.Something everyone has seen the explanation unsatisfactory if the alluvial environment and freshwater lakes, inevitably there is a horseshoe lake created by river delta (truncated segment of the river) in the old river meanders by service cross On the other hand in terms of composition alluvial rhythm had to order from the bottom up is sandy riverbed property, alluvial clay powder, clay lake That is only for large rivers and alluvial clay or clay powder reservoir never created the thick seams and disseminated taking into account the region Meanwhile the sedimentary rhythm curve back carota and petrographic samples varied from continental (alluvial - 31 proluvi) to continent - sea (alluvial - delta - bays) moved from lowstand systems tracts (LST) region on the system During analysis, benchmarking but still no real comprehensive data and synchronize documents, but with the level in JV "Vietsovpetro" and the results of additional analysis slice petrographic samples, sample analysis ronghen quantification may allow describing some lithofacies - ancient geography in low marine systems and transgressive as follows: 3.1 LOWSTAND SYSTEMS TRACTS (LST) 3.1.1 Pebble deluvial facies Coarse sediments are considered deluvial bottom sediments lining of basins, distributed mainly in the valleys and slopes of terrain lift blocks on the continent Currently many negative reviews want coarse sediment in Eocene continental scope the Cuu Long basin for the simple reason that they are not caught in the drill hole However on seismic sections of the horizontal line at Bach Ho can discern a liner bottom sediments very rough, composed of the reflector blocks with no sharp discontinuity On the other hand is also very easy to understand why the borehole was not met because property overburden drill holes positioned virtually been selected on the uplift, where the terrain is the main erosion even if more is the destruction is created Meanwhile wells at the periphery met with Eocene conglomerate deluvial that can prove our statements to be true Pebble deluvial facies is not shown on the map facies - ancient geography because sedimentary facies are distributed directly on shrinking government granitoid foundation was just performing mapping sedimentary environment at the end of the cycle early Oligocene (sh11) 3.1.2 Gravels and sands alluvial – proluvi facies Coarse sediments, the one-way flow of continental very popular in the early Oligocene stage, but occupies a large area and not move very quickly into estuary facies When the continental crust began broken, the system acts as faults cause the formation of basin The process of weathering, erosion, transport 32 and deposition of sediments occurs simultaneously with tectonic activity So alluvial sediments - proluvi only distributed in the saddle and moving terrain facies abruptly down the deltas and estuaries and little scale Thus, the existence of alluvial- proluvi sediments continent is inevitable in stage break, differentiation foundation But the river development during this period was not just a few rivers such as the notion that authors are endless "river" is not short and steep operating name on the tectonic valley duty coarse material conveyed by destroying the foundation and forms of physical weathering So traces of sediment, river - only the lens stream of facies pleased that deficiencies or incomplete facies alluvial sediments and horseshoe lake On the map lithofacies - ancient geography, facies alluvial distributed around the block in the center protruding foundation Bach Ho with narrow area and the direction of flow is shown with symbolic derived from the erosion area dump NW and SE of the basin 3.1.3 Sand, sandy estuaries facies Many short and slope flow into the bay beach has created a series of phase interferometry and connect with each other intermittently The lens type sands are not thick and be thin neckties very fast in the direction along and perpendicular to the shore According cross the sand move up the silty clay and rhythmic structure Considering the composition of a sedimentary sand - silt - clay similar to fish scales On the map lithofacies - ancient geography, sand - silt - clay estuary fan facies is represented by orange distributed in the central area surrounded minister alluvial sands lithofacies According to the classification of Pettijohn, group sandstone including rocks following base: Large sandstone mix of medium and small grains grainy acko, poor cement, poor sorted and poor rounded (Ro < 0,5; so ≥ 3,0) The composition of minerals include quartz magma 25-355, plagioclase 15-25% (including acid and neutral plagioclase) Potassium feldspar 5-10% mainly been pelit octoclase goods Secondary alteration phenomenon common to large grain 33 sandstone was calcite phase of property, of which the most common is neutral plagioclase, second as zeolite and chlorite chemical At the same time with the process of forming new minerals are exposed boundary of the crushed quartz particles - quartz, feldspar - quartz, feldspar - feldspar and between minerals with stone pieces have been altered very strong Mainly grain boundaries are curves and jagged, secondary alteration coefficient from 0.75 to 1.0 That represents three processes cause secondary alteration is compression - soluble - recrystallization occurred simultaneously and rock has reached the variables stage Therefore the effective porosity is reduced significantly, with only 5-1% Figure :Grauvac sandstone small particles, cement base filled, rich acid rock fragments, rock weathered weak Figure :Acko sandstone large grain , plagioclase and rock fragments of equipment perit Quartz sandstone - litic large particles to small particles to be distinguished from the content acko fragments rise (from 15 to 30%) Mostly rock fragments andezite, daxite and riolite Figure : Quartz sandstone - lytic midsize, cement filled - exposure, Figure : quartz sandstone - lytic small particles, regenerated contact cement Metagenes soon change, 34 environment : alluvial - fans Clayey silt sediment interspersed among estuary fan transitional nature continent - sea The alternating rhythms that make up the symmetry: sand silt - clay claystone silt in a thin lens type, multi-mineral composition, poor sorted (So ≥ 3.5) is formed in the hydrodynamic conditions and weakened the energy environment when form sandstones 3.2 TRANSGRESSIVE SYSTEM TRACTS (TST) Forwarding lithofacies group includes the group: • • Clay shallow bays Clay limestone bays Clay is common rocks and environments characterizing bays and also the best oil source rocks of the Cuu Long Basin Clay bays facies including pure clay with good sorted (4235.02) accounted for a very small percentage than clay contains organic material (4226.5, 4126.5, 4321.9, 4231.7) On cross lithofacies - acient geographic clay bays offshore software development and the top of the Result analysis of petrographic and geochemical features indicate some of the following: Sandstone formations in alluvial and estuarine fan environments with multi-mineral components including: - Sandstone acko - Sandstone acko - litic - Quartz sandstone - litic - Sandstone grauvac - Sandstone grauvac – litic Feldspar very diverse components: octoclase and acid plagioclase (from granite), neutral plagioclase (from quartz diorite and diorite), single-crystal 35 quartz (from granite) and very popular eruption fragments rock (daxite, andezite, riolite) Sandstone was formed in this stage is similar to the previous period sh11 which have mineral composition similar to bedrock minerals They are destroying the foundation stone of the region enhanced erosion and transport costs are very close, less radical differentiation They have a different rounded (Ro = 0.3 to 0.8), but are generally less rounded, poor selectivity shows the energy flow to the bay continental strongly but wave energy weak due to terrain meandering shore bays, semi-enclosed Figure : sandstone acko - lytic small particles, cement filling: xenrixit and organic material rock fragments: daxit and andesite Figure : Acko sandstone - medium grain, medium selectivity, potassium feldspar be perit strongly, cement contact recycled Claystone, marl bays is a testament to the marine environment alternating delta front environment amount reflecting the marine transgression and regression in relation to tectonics Period from sh10 to sh8 (to be late Oligocene) can be considered reflective surface boundary sh10 is the boundary of two sub strata geological structure features two tectonic context 36 CHAPTER IV EVALUATING THE POTENTIAL PETROLEUM BASED ON OLIGOCENE SEDIMENTARY ENVIRONMENT RESEARCH 4.1 EVALUATING SEDIMENTARY ENVIROMENT OF SOURCE ROCK 4.1.1 Eocene - early Oligocene period (from nail to SH10) During the development sediments phase from Eocene to early Oligocene (foundation to SH10) occurred in stages with three parasequence sets: - Ps1: from foundation to SH12; - Ps2: from SH12 to SH11; - Ps3: from SH11 to SH10 From foundation to SH11 (Ps1) in Bach Ho area shown on the lithofacies ancient geography map in the late SH11 The clay facies, clay lime facies in estuary bays have a large sediment thickness over 600m This deep basins subsidence with high speed, so it is a good chance for quick burial of organic matterial in the sediment Organic matterial content is from 0.12 to 0.47% of type II kerogen (marine mammals) create the accumulation of oil in the marine environment and type III accumulation of gas created in coastal marshes deltas front facies Pr / Phy changed from 1.65 to 2.34 is also fully consistent with relationship diagrams HI / Tmax set by Tran Cong Cao, 1996 Although sedimentary environment mostly weak denitrification, organic matterial 0.3 have demonstrated that hydrocarbons are present not only move in Ologocen but also in the lower Miocene and fractured basement Reviews: Source rocks Oligocene reach the criteria of an oil source rocks to best create Cenozoic, under facies deep bays clay, clay swamp - deltaic shallow bays contain high levels of TOC (> 0.5%) and kerogen mainly type I and II, the potential for big oil Miocene sedimentary poor organic matter ( 2.5; Ro 1.6) • Sand dike sure estuaries facies and coastal bays sand development within deltas and coastal amount of and ancient bays These are the great base sand, with an average selectivity (So > 1.5), fine rounded (Ro = from 0.5 to 0.8) • Lithofacies - ancient geography sections outlined an evolutionary picture facies under two dimensions: time (vertical) and over space (horizontal from the shore out to sea) This is the replacement, symbiotic facies in relation to the variable component particles and the energy decreases in both directions above However the nature collector (Me and K) of Lower Oligocene sand still of similar poor Bach Ho with Me = 8-1%, permeability coefficient - 5mD 4.3 Characteristics of seal rock Research lithofacies - geographical ancient may indicate the laws of formation and distribution of certain layer Sediments are considered seal layer with the following criteria 40 About lithological: Must be a clay layer, marl stone, containing no or negligible rate of powder particles (> 0.01mm) Preferably seal layer are monmorilonit clay About porosity and permeability: impermeable layer layer is definitely there Me = and K= 0mD About thicknesses: layer thickness must have been large enough to withstand strong pressure, which can cause pressure permeability or permeable partial model "leaks" in particular oil and gas About the size distribution: to create seal the seams wide stratigraphic traps coated or trapping structure Score classification: layer subclass seal low coefficient Oligocene two mining areas Rong and Bach Ho to form local levels have seal localized sometimes coincides with source layer Example: Delta facies clayclay and clay shallow sea lagoons development interspersed with sand lens acts as a reservoir rock There are levels in order to be seal quality is as follows: Layer I: Lower Miocene sediments with a thick rotalit clay layer from 60 - 150m acted as layer area can called perfect This clay is quite homogeneous, the alternating layers of siltstone very less, mainly mineral composition monmorilonit is taking swells make great base shielding Layer II: Located in Bach Ho Formation and reflectors located on SH5 This layer length from 80 - 110m clay mineral composition mainly hydromica, monmorilonit, kaolinite and chlorite less shallow sea facies Layer III: Located above the Tra Tan Formation, coincides with the reflector SH7 Thickness varies from 101 - 210m in the Eastern Rong and fell in the western valley In sediments Rong is very thin, the powder phase and sand so incapable petroleum seal Layer IV: Situated on the roof of Tra Cu Formation thickness varies from 39m to 210m In general, low clay content, often containing powder and sand particles However rock is strong compression, the mount should make very low permeability 41 CONCLUSION A sequence contrains three system tracts: lowstand systems tracts (LST), trangressive systems tract (TST) and highstand systems tract (HST) A system tract is composed of association facies belong to horizontal (space) and vertical (time) According to the space, from erosion area to center basin: continetal – coast – bay In the time, from the end of a sequence to blank: continental – coast – bay Association facies following the time (vertical) and the space (horizontal) is a geometical structure according to cause – result rule in relation tectonic mechanisms and sea level (estuary) to creat a basin Research the relationship between Me and the parameters of sediment has a practical significance and enormous theoretical insights help of law essentially affect the nature of oil and gas collector In that amount of 42 cement, cement and matrix components, the degree of secondary alteration and basin depth are factors directly affecting the quality of collector in relation to geodynamics Sedimentary parameters have a relation together in the following rules: - When the average particle size in the range of 0,05mm to increase 0.15 mm; decrease of rounded, quite closely correlated (r = -0.91) Such environmental proved still affected by one direction flow - Increased quartz content and grain size increased (r = 0.78) is fully consistent with the correlation between the concentration of quartz (Q) and cement content (Li) in the inverse direction (r = -0.71) Secondary alteration of the sandstone was studied quantitative computed compression coefficient (Co), coefficient of secondary alteration (I) and the influence of the composition of sediment to the decrease porosity According stratigraphic depth decrease porosity, degree of secondary alteration related increase to basic reasons are gradually increasing hydrostatic pressure and pressure rise suddenly one afternoon at the end of SH10 and SH8 43 44 [...]... Tropic space marine accumulation will create marine lithofacies group: shallow marine, deep sea • When MNB are in the lowest position: The distribution of continental lithofacies is the most extensive of which occupied mainly alluvial lithofacies Deltaic and marine lithofacies occupying an area of very narrow compared to the continent in on site lithofacies of a sedimentary basin When MNB are in the highest... can be group alluvial lithofacies formations marine degradation in the environment is continental, deltaic marine lithofacies group was formed in the transitional environment and ocean marine lithofacies quit the group was formed in the marine environment The lithofacies next group could be transgressive marine lithofacies group (marine environment), transgressive group Delta lithofacies (Environment... likely to contain less rock 2.3.2 Analysis characteristics lithofacies – acient geographic Map Geographic lithofacies ancient is synthesized two important factors are geographical lithofacies and ancient Lithofacies are factors lithological environment and ancient sediments And ancient geography are factors reflect the picture of 1 sedimentary basins such as intrusion region (ancient continent) and sedimentation... CHAPTER III CHARACTERISTIC OF ANCIENT GEOGRAPHIC LITHOFACIES IN BACH HO BASIN This is the beginning stage of the history of formation and evolution in the Cenozoic sedimentary basin Bach Ho mining areas On cross restored geological structures can be observed a vivid picture of the "dawn" recorded the imprint destroyed by continental crust 10 active fault systems oriented NE - SW created composed of 3 zones:... in mining company of Bach Ho This event promotes quickly oil exploration activities in the region Bach Ho and Rong A series of wells and mining exploration was conducted at two mines Rong and of Bach Ho as well as in the adjacent structure as Ba Den IX, IX Tam Dao, Ba Vi IX The discovery of oil in the basement granitoid not only increase mining output of Vietsovpetro in the Bach Ho and Rong but also... Oligocene sediments Bach Ho in Cuu Long Basin" of the authors Nguyen Dich Dy, Tran Nghi et al works Minister discusses the most complete ancient stone Bach Ho geographical area as of 1997 In this work, the author of the project has clarified the conditions of deposition of oil and gas bearing formation in the Lower Oligocene sediments of Bach Ho in Cuu Long Basin to provide the scientific basis for... position: shallow and lithofacies relay sea occupies the largest area occupied most of space was lithofacies sedimentation continent distributed only to a narrow range along the edge of slopes built mainly river-flood lithofacies mountainous and midland Thus an area of 3 tropical space will never fixed but constantly being expanded or narrowed as shoreline move by lowering or rising MNB 2.3.4 Interpretation... shallow marine limestone characterized by complex dual sequence including sequence deltaic terrigenous lower sea in sequence interspersed terrigenous shallow marine (amr / mt) When shoreline reached maximum position in the stage of formation rather uniform sea clay is widely distributed from the center of the basin to the edge of the basin edge This phase sedimentary basin subsidence extending section... history of oil and gas research Cuu Long basin especially Bach Ho and Rong terms of stratigraphy, seismic, tectonic and geochemical carota petroleum development fairly quickly, the study lithofacies – acient geographic has only been started in recent times We can say the theme "The conditions deposition of sediment - acient geographic of oil and gas bearing formation in Lower Oligocene sediments Bach Ho in. .. number of exposure points and monitoring lines in the ith row Bi - Number of secondary exposure (curve, combined, aliasing) in line ith observation n - Total goods observed in thin slices The value of I variable from 0 (min) to 1 (max) and can be divided into the following ranges of values: I = 0 - 0:25: early rock stage 12:25 -0.5 rock late stage 0.5 - 0.75 katagenes 1.75 - 1.0 metagenes 2.3.1.5 Method ... CHAPTER III CHARACTERISTIC OF ANCIENT GEOGRAPHIC LITHOFACIES IN BACH HO BASIN This is the beginning stage of the history of formation and evolution in the Cenozoic sedimentary basin Bach Ho mining areas... distribution of continental lithofacies is the most extensive of which occupied mainly alluvial lithofacies Deltaic and marine lithofacies occupying an area of very narrow compared to the continent in. .. contain less rock 2.3.2 Analysis characteristics lithofacies – acient geographic Map Geographic lithofacies ancient is synthesized two important factors are geographical lithofacies and ancient Lithofacies