characteristic of ancient geographic lithofacies in bach ho basin

Tasks of research subjectsCharacterize oligocene sedimentary facies in the region bach ho - cuu long and composition relationship to each other Study characteristics sandstone lithology,

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 parametersthereby 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 Vietnamwhich has a large oval structure terrian and subsidenced in theCenozoic as well as surrounded by the high Mesozoic zone Thissedimentary 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 theNam Con Son basin is the uplift of underground zone Con Son, runalong the existing islands like Hon Khoai, Hon Trung - Con Son.Sediment inside the basin consists mainly of terrigenouscomponents Coarse and fine aged Eocene - Oligocene to earlyPliocene – Quaternary

-Kainozoic sediments thickest reaches nearly 7,000m

Current seabed depth not exceeding 50 m, as favorableconditions for research and exploration and exploitation of oil andgas

1.1.1 Tertiary stratigraphy

Tertiary strata in the Cuu Long basin is divided intostratigraphic 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 withclay powder layer containing pebbles, grit and gravel Cobblesoffers various lithological composition, mainly andesite and graniterock Early Oligocene - Tra Cu Formation formed in the area ofenvironmental 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 over1,000m According to seismic data, expressed in Formationseismic episode which Vietsovpetro joint venture company known

as collective E; corresponding bottom seismic episode very littledifferentiation, continuous low level, relatively large amplitude,low frequency, there is no rule subclass, often coveredunconformity directly above the basement rocks

In sedimentary formations of ancient ruins born very poor; onlyfew pollen spores: Magnastriatites howardi, Verrucatosporites,Triletes, Pinuspollenites, Oculopollis Eocene - Oligocene,determined by Oculopollis (LAD in late Eocene) andMagnastriatites howardi (FAD in late Eocene) However, based onstratigraphic relationships, Tra Cu Formation Oliocen early age bylying on the Ca Cối Formation (Eocene)

1.1.1.2 Late Oligocene - Tra Tan Formation (E32tt)

Late Oligocene - Tra Tan Formation sandstones include small tomedium gray grain white, carbonate cement, moving to the topwith multiple layers of siltstone, claystone brown and black,alternating thin layers of coal, place contains glauconite.Formation sediments rich in organic materials Sapropelamorphous forms, organic material forms arise in conditionswithout oxygen tank This property Morley called "GeneralSapropel" while analyzing wells in Lot 15 Also facing freshwateralgae as Pediastrum, Bosidinia The altered rocks in the late phaseCatagen

Tra Tan Formation widely distributed than Tra Cu Formationthickness and relatively large changes in different areas of thebasin Tra Tan Formation sediments have alternated betweenclaystone (accounting for 40- 70% of the sections, especially in thenortheast lots of basin), siltstone, sandstone, and in many places

Tra Tan Formation environment formed in rivers, deltas andlakes - coastal wetlands - the shallow sea bays Tra Tan Formationthickness observations wells ranged from 400 to 800m, while inthe valley can reach 1,500 meters.

1.1.1.3 Early Miocene - Bạch Hổ Formation (N11bh)

Early Miocene sediments - Bạch Hổ Formation wells described inBH1, from 2037 to 2.960m depth Sediments include thin-beddedsandstones, siltstones, dark gray, gray-green (bottom) alternatinglayers of sandstone siltstone gray to brown; gray-brown clay andclaystone gradually to gray-green, homogeneous (above),containing fossilized marine animals should Rotalia group calledclay Rotalid (mainly ammonia size 1/10 mm) The thickness of theformation varies from 400 to 1000m

Throughout the Cuu Long, Bạch Hổ formations developed quiteextensively The lower section consists of sandstone of differentgrain size alternating siltstone and claystone, some areascontaining debris in energy conditions vary sharply from region toregion Above, in most developed place claystone, contains manyshallow 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 ascendingtrend going from the edge of the basin southwest through thecentral 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, anddinoflagellates: Cribroperidinum, Apteodinium given early Mioceneage formations

1.1.1.4 Middle Miocene - Con Son Formation (N12cs)

Middle Miocene sediments - Con Son Formation withsedimentary materials include quartz sandstone, small grain are

predominantly coarse-grained mix of grades 1-2 choose fromaverage to poor, clay and cement is less carbonate , above havelittle alternating layers of clay and silty brown, gray and coallenses The thickness of the formation varies from 650 to 1000m.Con Son Formation extensive distribution throughout the CuuLong basin Sedimentary environments of formations moved fromrivers, deltas, coastal marshes to shallow sea.

In the sediments of Con Son has discovered pollen and spores

of fossil foraminifera and Nannoplankton including Florschuetziameridionalis, Lepidocyclina (TF2), Orbulina universa (N9),Calcidiscus marcintyrei (NN4-NN19) to Middle Miocene age

1.1.1.5 Late Miocene - Dong Nai Formation (N13dn)

Late Miocene sediments - Dong Nai Formation sedimentarymaterials include the layers, sandstone small to medium grain,moving gradually up the alternating sandstone siltstone, claystoneand 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 theearly stages, new rock mounted only weak or even loose and easy

Formation can be divided into two parts - the lower part isrough quartz sand, gray and white contain foraminifera fossils

Operculina heading (to the Pliocene) and part on theunconsolidated Quaternary sediments The thickness of theformation varies from 200 to 500m.

Bien Đong Formation (lower section) distributed across theCuu Long basin-wide development in the region, mainly in theform of environmental and shallow marine estuary with sedimentstill weak under tension

In sediments (under low part) Bien Dong formations foundabundant fossils include pollen spores Dacrydium, Stenochlaenalaurifolia and Foram Sphaeroidinella subdehiscens (N19), NanoDiscoaster intercalcaris (NN12) given Pliocene age

1 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 portionlocated on land within the area of the Mekong River mouth, andmost of the area is located on the continental shelf of Vietnam.Cuu Long basin-shaped "oval" is located along the coast of BinhThuan Vung Tau-, this is an internal continental sedimentary basintypically enclosed in Vietnam continental shelf basin structuresdeveloped in the NE - SW, strong subsidence in Kainozoi and filled

-by sediments from rough to smooth Eocene aged In view of thestratigraphic formations set includes the complete set of complex:Eocene, Oligocene lower on Oligocene, Miocene lower, middleMiocene, Miocene on, Pliocene - Quaternary

Currently, the Cuu Long basin bordered the mainland to thenorthwest, separated from the Nam Con Son basin by Con Sonuplift, the uplift southwest and northeast Korat-'s Natuna shearzone separates Tuy Hoa Phu Khanh basin

1.2.2 Characteristics tectonic faults

The study area was the complicated and is cleaved intodifferent blocks by different fault systems Based on the activity ofthe 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 havedifferent geographical location, age, shape, amplitudedisplacement, angle and intensity plugging operations as well asthe role they have on the formation of oil in the nail itself is alsodifferent

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 southeastside of Bach Ho These are overthrust fault is born into by localcompression phase occurring in late Oligocene close, theycontinue to operate during the late Oligocene to early Mioceneearly, demonstrate their activities while longer exists in untilfinished off local compression

Given the strong compression that basement in Bach Ho blocksmashed the system creates fissures crisscrossing dense Because

of time formed after the early Oligocene sediments should thesecracks are not filled by the debris so they have created a massivehole and connected together makes the permeability increase andfacilitate movement and hydrocarbon accumulation in the emptyspace 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 borninto a foundation during the late Mesozoic smashed, some of themhave nonstop activities from the majority of the foundation stillothers continue during rifting activity with other faults have beenborn into during rifting Late Oligocene to near the end, most ofthe 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 theCuu Long Basin area The main fault systems were split Cuu Longout of various blocks The success of they born in the early stages

of rifting period and continue to operate during a break there andalso end late Oligocene Amplitude shift of this fault system issmaller 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 northand central part The active faults primarily on early stage riftingand then rest, activity, their role is only further complicated theinternal 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 areborn into early and continue operating in the period rifting andalso at the end a break operations late Oligocene These two faultshave 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 LongBasin, as well as integration with document tectonic stress field

nearby, Cuu Long basin is believed to have directly influenced bytwo 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 fieldtook place in the period from late Eocene to Oligocene, Cuu Longwas split open maximized

-The maximum compression under the meridian and maximumextension according to the latitude This phase happened in theperiod from early Miocene until today The consequences of thistectonic stress field corresponds to the period after the rifting ofthe tank and the system creates reverse faults, overthrustaccompanying slide translate to widespread development in thewhole study area

1.3 LAYERED STRUCTURE OF CUU LONG BASIN

According to seismic data - geological and drilling material andother documents already, structural geology study area can bedivided into two-story main structure follows:

Part structure under include Pre-Kainozoi formations withrocks and that the heterogeneity of the lithological composition ofrocks and colorful They include granite, biotite, granitoid,granodiorite and many places are experiencing both riolit andmetamorphic rocks According to the analysis of isotopicradioactivity was identified as the Jurassic, Cretaceous of Da Latzone - Cambodia These wells have encountered basement rocksweathered and cracked foundation on the raised zone is mainlyand sometimes granite or granodiorite and sometimes bothmetamorphic rocks

Part textured include Cenozoic age from Eocene toQuaternary They cover the unconformity on under part of thestructure Part of this structure is divided into three sub-sections ofdifferent structures The division was based on lithologicalcharacteristics, history and sedimentation environment Theboundary between the sublayer structure is the unconformitysurface, marking the sedimentary cycles associated with thephase corresponding tectonic activi

CHAPTER II HISTORY OF RESEARCH AND RESEARCH METHODS

2.1 HISTORY OF RESEARCH

2.1.1 The period before 1975

From 1969 to 1975, the exploration work in the Cuu Long basin

is mainly deployed on surface geophysics Only one BH-IX wellsare made on the basis of results of processing and interpretation

of seismic data collected, in 1974 the Mobil company decided todrilled wells first on the structure of Bach Ho, which is well BH-IXdrilling and wells also the first from this, Mobil discovered crude oil

in the Oligocene and early Miocene flow with 2400 barrels / day.Also during this period, the company Retty Ray has conductedseismic surveys in more detail under the 2x2 km route network inthe region made up of Bach Ho From May 4/1975 two companiesMobil and Retty Ray to stop job searching and exploration of them.During this period, do not have any document regardinggeochemical wells BH-IX is retained only one report on the drilling

of wells BH-IX is recorded to March 3/1975 In the document alsorefers to the appearance of gas during drilling Such geochemicalresearch for the first wells in the period before 1975 as no

2.1.2 The period after 1975

Starting in 1976, the Company's Geophysical France CGGcoordinate with the General Department of Vietnam Petroleumconduct seismic survey in the Mekong River delta and shallowseas to link seismic plots 9 and plots 16 between the mainland.Results from the link above, Petro Vietnam General Departmenthas conducted exploratory drilling two wells CL-IX and HG-IX in theMekong Delta The results of this drilled two wells allowedgeologists Vietnam Petroleum tracking the change in sectionsTertiary sediments from the land to the central area of the CuuLong Basin

In 1987, the Company Geophysical Pacific has conductedseismic surveys under the 2x2 km route network and 0.5x0.5 km

on texture of Bach Ho and 2x2 km, 1x1 km on structure Rong, TamDao Tra Tan and the Cuu Long, the total number of up to 3,000 kmsurvey line, volume geophysical work quite voluminous anddetailed important premise for the Vietsovpetro company choosethe appropriate exploration wells in the area bidding anddiscovered crude oil in the Oligocene and Miocene of of Bach Hotexture

The company Vietsovpetro has added more and more theexploration wells, amount and type of geochemical samples on alot and the results are more abundant and more reliable However,

at that time by the analysis equipment is somewhat limitedcompared to now be localized parameters are not effective enough

so that an assessment of each well drilled localization is limited.However remarkable result here is from this initial study,Vietsovpetro has discovered crude oil in the Oligocene andMiocene of of Bach Ho texture

From 1990 until now, an event caused the petroleum geologistsand foreign amazed and exciting is the discovery of crude oil infractured basement granitoids before Tertiary age of Vietsovpetro

in mining company of Bach Ho This event promotes quickly oilexploration activities in the region Bach Ho and Rong A series ofwells and mining exploration was conducted at two mines Rongand 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 basementgranitoid not only increase mining output of Vietsovpetro in theBach Ho and Rong but also great contribution, promote and attractother foreign companies invested in the exploration Cuu Longbasin

At present, all companies are present in Cuu Long asVietsovpetro, Petronas, JVPC, Enterprise Oil is continuing to drilledadditional exploration wells Also there are plenty of foreign oil and

gas companies are in talks to sign a contract with PetroVietnam inthe area have not been tendered in the Cuu Long Basin.

Particularly Rong and of Bach Ho, research is increasingly beingconducted detailed In 1987, the Institute of Marine Research and

TK Petroleum (NHIPI) of Vietsovpetro link building structure theplan for the top and bottom layer, map the distribution ofthickness and effective thickness of the reservoir sedimentsOligocene reservoir in Northeast Rong In 1995, the explorationGeological Institute document NHIPI used geophysical wells, 3Dseismic data link details the sediments Oligocene reservoir underthe North East Bach Ho Thereby determining the distributionrelationships of rocks of Oligocene lower layer with documentscarota, seismic, the expression of layer entitled, aquifers topredicted the development and distribution of the Oligocenereservoir rock layer below in areas with limited drilled hole data,relying primarily on seismic

If the history of oil and gas research Cuu Long basin especiallyBach Ho and Rong terms of stratigraphy, seismic, tectonic andgeochemical carota petroleum development fairly quickly, thestudy lithofacies – acient geographic has only been started inrecent times We can say the theme "The conditions deposition ofsediment - acient geographic of oil and gas bearing formation inLower Oligocene sediments Bach Ho in Cuu Long Basin" of theauthors Nguyen Dich Dy, Tran Nghi et al works Minister discussesthe most complete ancient stone Bach Ho geographical area as of

1997 In this work, the author of the project has clarified theconditions of deposition of oil and gas bearing formation in theLower Oligocene sediments of Bach Ho in Cuu Long Basin toprovide the scientific basis for the calculation reserves for thedesign and engineering exploited economically

2.2 METHODOLOGY

Cuu Long spent 6 phases tectonic with 6 cycles basic sedimenttype 1, for a complex set following six:

S1 (32- 26 million years): corresponds to Eocene - Oligocenelower (E2 – E31),

S2 (26- 21 million years): corresponding to the Oligocene on(E3 ),

S3 (21- 16 million years): corresponding to the lower Miocene(N1 ),

S4 (16- 11 million years): corresponding to Middle Miocene(N1 ),

S5 (11- 5 million years): from SH1 corresponding Miocene on (N1 ),

SH2S6 (5 million year to date) corresponding to the Pliocene Quaternary (N2 - Q)

-The study details the relationship between sequencestratigraphy, sediment cycle and characteristics lithofacies –acient geographic for accurate geographic strata and evaluation ofmineral potential involved

To understand the sequence stratigraphy and geological historyevolution Kainozoi sedimentary basins deep continental shelfwaters of Vietnam should reach in view of the system and solvethe causality between the elements: sediment and sea levelchanges, sedimentary and tectonic movements, magmatism andtectonic movements Which components magmatic andsedimentary petrography have relationships with different tectonicactivity

Between sea level and tectonic movements also cause andeffect relationship Tectonics and mantle relief motivation oceanridge on the whole planet in the Tertiary may be the cause of thechange in sea level static foot Also in the Pliocene - Quaternarysea level changes related to the static vacuum primarily to glaciallocal tectonic movements cause obvious changes relative sea level

and pace that creates division in the county one cycle andtransgressive marine degradation.

Based on seismic analysis and general minister may dividelithological sedimentary sections Kz deep waters into 6 complexset (sequence) corresponding to 6 cycles of sediment

Each sequence vertically from the bottom up with 3 sedimentdomain system:

- Domain lowstand systems tracts (LST): The space distribution

of sediment deposition over a wide area runs from continentalenvironment (ar) to forward enviroment (deltas and small coastallagoons) (amr) end is shallow marine environment or bays formingthe double delta complex marine minister quit mainly alternatingshallow sea (mt / amr) On seismic sections of the synchronizedwave white reflector, chaotic, fragmented inclined orientation isreflected coarser sediments layered structure obliquely orientation

of riverbed (ar) The government stepped up wave form (downlap)was a wedge formed underground growth of the delta (Delta andprodelta) Thus, the stage lowered sea levels from the averageposition to the lowest position called lower marine degradationphase has created a symbiotic minister ranges from tropical alongthe edge to the center of the basin

- Domain transgressive systems tracts (TST) is the accumulation

of sediment space from the center of the basin to the boundarybetween the domain and the domain erosion sedimentaccumulation Center basins in deep water basin burstscharacterized sequence lime mud, clay or mud shallow marinelimestone characterized by complex dual sequence includingsequence deltaic terrigenous lower sea in sequence interspersedterrigenous shallow marine (amr / mt) When shoreline reachedmaximum position in the stage of formation rather uniform seaclay is widely distributed from the center of the basin to the edge

of the basin edge This phase sedimentary basin subsidenceextending section 2 complexes sediments from below to

sequence: sequence terrigenous complex river - (amt) (below) andshallow marine clay complexes sequence (Mt) (section above) Onseismic sections clearly see the parallel transverse wave fieldinterspersed with waves have formed the government steppedreflects a dual complex geometry sequence phrasing includedeltaic terrigenous sequence lowered due to fluctuating sea localalternating in shallow marine marine transgression sequencebackground.

- Domain highstand systems tracts (HST): When the sea level

lowered from the highest position to the average position ofsediment accumulation space is similar in low sea phase (LST) andmarine transgression phase (TST) However symbiotic range faciesown nature characterize high degradation sea phase This stagecommonly deltaic terrigenous marine sequence degradationgrowing wedge geometry typical of underground Delta (amr)changing to dual sequence terrigenous complex deltaic shallowmarine clay alternating phase sequence sea (mt / amr) Regionalsystems of marine sediments corresponding tectonic contractionphase, compression, lift the edge of the basin protruded sides andweak subsidence in the central area

The relationship between sequence , sea level changes andtectonic movements Kz deep waters basin (Tran Nghi, 2012)

2.3 RESEARCH METHODOLOGY

2.3.1 Analytical sedimentary petrography methods

2.3.1.1 Analytical thin slices of petrographic methods

Analysis petrographic thin slices under polarizing microscopyallows to identify: cement content, cement composition, cementtype, texture and structure of rocks, mineral composition, theprocess secondary alteration thereby allowing accurate stonename

On the basis of the percentage content of the rock-formingminerals underlying quartz%, plagioclase%, potassium feldspar,rock fragments types and levels of cement% chemical matrixallows identifying name Pentijohn rock charts, 1973.

To determine the context of the tectonic sedimentation basinsecondary more research Qm targets (quartz single crystal), Qp(quartz crystal), P (plagioclase), K (potassium feldspar ), Lv(extrusive rock fragments), Ls (piece of sedimentary andmetamorphosed sediments) and use the chart Dickinson, 1989.Since then can recommend how to classify and name the stone asfollows:

For mechanical sedimentary rock debris there are many ways toclassify and name The concept called sandstone before the 70swere Pentijohn, 1973 proposal to change the previous example weconceive sandstone rock grauvac is poor or no cement as acko butmust be present mafic volcanic materials as basaltic tuff rockfragments, fragments of basalt and mafic minerals such aspyroxene origin, olivine, plagioclase bazic that in fact verydifficult to find and common model, recognized the unilateral tiesbetween 1 sedimentary basins with material supplies is ridiculous.Based on the classification of Dott, 1964 and additional repair ofPetijohn, 1973 we proposed a simple pattern classification used.Which 3 most important factors to be taken as a basis forclassification is the quartz content, levels of background (matrixand cement) and the ratio of feldspar (F) on a piece of stone

Each triangle in triangles 2 classification is divided into fivecases (Figure 1) and the name of field is based on the content ofthe background and content of the 3 components of quartz (Q),feldspar (F) and rock fragments as follows:

 Field 2: quartz sandstone – acko : Q = 75 - 90%; F/R > 1

 Field 3: quartz sandstone – litic Q = 75 - 90%; F/R < 1

 Field 4: sandstone acko Q < 75%; F/R > 1

 Field 5: sandstone acko- litic Q < 75%; F/R< 1

As background concentrations above 15%

 Field 2: quartz sandstone – grauvac Q = 75 - 90%; F/R > 1

 Field 3: quartz sandstone - Litic: Q = 75 - 90%; F/R < 1

 Field 4 : sandstone grauvac Q < 75%; F/R > 1

 Field 5: sandstone grauvac- litic Q < 75%; F/R < 1

2.3.1.2 Research morphological debris particles method

High rounded (Ro): Typical for motivation mode of sedimentaryenvironment, save time and distances of debris particles movingparticle debris Rounded degree is calculated according to themethod proposed Nghi Tran, Ro values change from 0 to 1 and isdivided into the following 4 steps:

Spherical (Sf) is isometric levels of debris particles isdetermined by the ratio between the two axes A and B and thechange from 0-1 can be divided into 3 levels:

2.3.1.3 Analytical the particles with petrographic thin slices method

The parameters of particles is important indicators to evaluateconditions and deposition movement of sediment, hydrodynamicproperties of the medium For unconsolidated sediments we usethe sieve and pipette to split the particles level underdecentralization and but for sandstone is no longer applied thismethod so only the method used to analyze thin slices

It is best noted as a petrographic thin slices slice anymeasurable particle size should not coincide with its true size,usually smaller, but not fixed

The method used was calibrated treatments suggested by TranNghi 2000

Correction formula is as follows:

T1, T2, T5 is a real particles concentration level (afteradjustment)

This formula but not including particles cement (ie, particles

<0.01mm) so the cement content measured will be converted intothe content of% of all particles We have:

T1 + T2 + + T5 = 100 - C6

Which C6: the 6th grade levels% (<0.01mm)

100

) C (100 T

5





2.3.1.4 Method of determining the degree of secondary alteration of sandstone

Method of determining the degree of secondary alterationbased on the type of secondary and number of particles exposure

of quartz and feldspar debris

Group A: Exposure to stone stage include:

Exposure + contact point line

Group B: Secondary Exposure:

Curve Exposure + combinations exposure + aliasing exposure.The degree of secondary alteration is characterized bysecondary alteration coefficient (I):





n 1

Bin

1I

Among them:

Ai - The number of exposure points and monitoring lines in theith 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 bedivided 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 for determining the Interleaved of

tin

1Co

Where: ti - the exposure of the i th particles size cut

Ki - the particles cut the ith row

n - is the total number of monitoring products

Due to the amount of particles in thin slices are alwaysgreater than the amount of exposure and no cement in stone andexposure only straight lines or more, the K - t = 1 So to Co max 1,the sample number is K - 1 Co vary from 0 (min) to 1 (max) Thefact that rock has Co = 0.4 - 0.6 is the best porosity and Co <0.4and Co> 0.6 is likely to contain less rock

2.3.2 Analysis characteristics lithofacies – acient geographic

Map Geographic lithofacies ancient is synthesized twoimportant factors are geographical lithofacies and ancient.Lithofacies are factors lithological environment and ancientsediments And ancient geography are factors reflect the picture

of 1 sedimentary basins such as intrusion region (ancientcontinent) and sedimentation region

Sedimentary basins include: size, shape, depth, shorelineancient, the ancient flow transport materials sediment - chemical