Petroleum geology features and research developments of hydrocarbon accumulation in deep ...

53 Pages·2015·7.32 MB·English

Pet.Sci.(2015)12:1–53
DOI10.1007/s12182-015-0014-0
REVIEW
Petroleum geology features and research developments
of hydrocarbon accumulation in deep petroliferous basins
Xiong-Qi Pang • Cheng-Zao Jia • Wen-Yang Wang
Received:26September2014/Publishedonline:3February2015
(cid:2)TheAuthor(s)2015.ThisarticleispublishedwithopenaccessatSpringerlink.com
Abstract Aspetroleumexplorationadvancesandasmost theburialdepth.(5)Therearemanytypesofrocksindeep
of the oil–gas reservoirs in shallow layers have been hydrocarbon reservoirs, and most are clastic rocks and
explored,petroleumexplorationstartstomovetowarddeep carbonates. (6) The age of deep hydrocarbon reservoirs is
basins, which has become an inevitable choice. In this widely different, but those recently discovered are pre-
paper, the petroleum geology features and research pro- dominantly Paleogene and Upper Paleozoic. (7) The
gress on oil–gas reservoirs in deep petroliferous basins porosity and permeability of deep hydrocarbon reservoirs
across the world are characterized by using the latest differwidely,buttheyvaryinaregularwaywithlithology
resultsofworldwidedeeppetroleumexploration.Research and burial depth. (8) The temperatures of deep oil–gas
hasdemonstrated thatthedeep petroleumshowstenmajor reservoirsarewidelydifferent,buttheytypicallyvarywith
geologicalfeatures.(1)Whileoil–gasreservoirshavebeen the burial depth and basin geothermal gradient. (9) The
discovered in many different types of deep petroliferous pressuresofdeepoil–gasreservoirsdiffersignificantly,but
basins, most have been discovered in low heat flux deep they typically vary with burial depth, genesis, and evolu-
basins.(2)Manytypesofpetroliferoustrapsaredeveloped tionperiod. (10)Deepoil–gasreservoirsmayexistwithor
in deep basins, and tight oil–gas reservoirs in deep basin without a cap, and those without a cap are typically of
trapsarearousingincreasingattention.(3)Deeppetroleum unconventional genesis. Over the past decade, six major
normally has more natural gas than liquid oil, and the steps have been made in the understanding of deep
natural gas ratio increases with the burial depth. (4) The hydrocarbon reservoir formation. (1) Deep petroleum in
residual organic matter in deep source rocks reduces but petroliferous basins has multiple sources and many dif-
thehydrocarbonexpulsionrateandefficiencyincreasewith ferent genetic mechanisms. (2) There are high-porosity,
high-permeability reservoirs in deep basins, the formation
of which is associated with tectonic events and subsurface
X.-Q.Pang(&)(cid:2)W.-Y.Wang fluid movement. (3) Capillary pressure differences inside
StateKeyLaboratoryofPetroleumResourcesandProspecting, and outside the target reservoir are the principal driving
Beijing102249,China force of hydrocarbon enrichment in deep basins. (4) There
e-mail:[email protected]
arethreedynamicboundariesfordeepoil–gasreservoirs;a
buoyancy-controlled threshold, hydrocarbon accumulation
X.-Q.Pang(cid:2)W.-Y.Wang
BasinandReservoirResearchCenter,ChinaUniversityof limits, and the upper limit of hydrocarbon generation. (5)
Petroleum,Beijing102249,China The formation and distribution of deep hydrocarbon res-
ervoirs are controlled by free, limited, and bound fluid
C.-Z.Jia
dynamicfields.And(6)tightconventional,tightdeep,tight
PetroChinaCompanyLimited,Beijing100011,China
superimposed, and related reconstructed hydrocarbon res-
C.-Z.Jia ervoirs formed in deep-limited fluid dynamic fields have
ResearchInstituteofPetroleumExplorationandDevelopment,
great resource potential and vast scope for exploration.
Beijing100083,China
Compared with middle–shallow strata, the petroleum
EditedbyJieHao geology and accumulation in deep basins are more
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2 Pet.Sci.(2015)12:1–53
complex, which overlap the feature of basin evolution in the world, despite being faced with challenges and prob-
different stages. We recommend that further study should lems today. The Former Soviet Union discovered four
pay more attention to four aspects: (1) identification of 6,000 mordeeperindustrialoil–gasreservoirsoutofits24
deep petroleum sources and evaluation of their relative petroliferousbasins(Tuo2002).Theoildiscoveredindeep
contributions; (2) preservation conditions and genetic basinsinMexico,theUSA,andItalycontributesmorethan
mechanisms of deep high-quality reservoirs with high 31 % of their present recoverable oil reserves (Kutcherov
permeability and high porosity; (3) facies feature and et al. 2008) and the natural gas discovered there makes up
transformation of deep petroleum and their potential dis- approximately 47 % of their total proved natural gas
tribution; and (4) economic feasibility evaluation of deep reserves (Burruss 1993). China, too, has appreciable
tight petroleum exploration and development. achievements in deep petroleum exploration. Compared
with 2000, the deep reserves discovered in West China in
Keywords Petroliferous basin (cid:2) Deep petroleum geology 2013 increased an average of 3.5 times. The ratio of deep
features (cid:2) Hydrocarbon accumulation (cid:2) Petroleum petroleum reserves increased from 40 % in 2002 to 80 %
exploration (cid:2) Petroleum resources in 2013. Of the 156 well intervals in the Tarim Basin that
havebeentestedsofar,58havegonedeeperthan5,000 m.
ThedeepdrillholesuccessrateintheJizhongDepressionis
1 Introduction as high as 21.4 %. A 5,190-m-deep ‘‘Qianmiqiao buried
hill hydrocarbon reservoir’’ was discovered in the Huang-
As the world demands more petroleum and petroleum hua Depression (Tuo 2002). Despite these achievements,
exploration continues, deep petroleum exploration has however, a lot of problems have also emerged in deep
become an imperative trend. As it is nearly impractical to petroleum exploration. These include (a) the difficulty in
expectanymajorbreakthroughinmiddleorshallowbasins understandingtheconditionsofdeepoil–gasreservoirsand
(Tuo 2002), petroleum exploration turning toward deep evolution due to the multiple tectonic events having taken
basins has become inevitable. After half a century’s place in deep basins (Zhang et al. 2000; He et al. 2005),
exploitation in major oilfields across the world, shallow (b) the difficulty in evaluating the resource potential and
petroleum discoveries tend to be falling sharply (Simmons relative contribution due to the complex sources and evo-
2002).NorarethingsoptimisticinChina,wheretherateof lution processes of deep petroleum (Barker 1990; Mango
increase of mid-and-shallow petroleum reserves is 1991;Domine´ etal.1998;Zhaoetal.2001;Jinetal.2002;
increasinglyslowingdown(Wangetal.2012).Atthesame Zhao et al. 2005; Darouich et al. 2006; Huang et al. 2012;
time, the world’s petroleum consumption continues to Pang et al. 2014a), (c) the difficulty in predicting and
increase. According to BP Statistical Review of World evaluatingfavorabletargetsduetothecomplexgenesisand
Energy 2014, from 2002 to 2012, the world’s petroleum distribution of deep, relatively high-porosity and high-
consumption increase was virtually the same as its petro- permeability reservoirs (Surdam et al. 1984; Ezat 1997;
leum output increase, with annual average oil and natural Dolbier 2001; Rossi et al. 2001; Moretti et al. 2002; Lin
gas consumption increases of 1.35 % and 3.14 %, respec- et al. 2012), and (d) the difficulty in predicting and eval-
tively, compared to the annual average output increases of uatingthepetroleumpossibilityindepositiontargetsdueto
1.47 % and 3.23 %. In China, however, the petroleum the complex deposition mechanism and development pat-
consumptionincreaseisfargreaterthanitsoutputincrease. ternofdeeppetroleum(Luoetal.2003,2007;MaandChu
According to National Bureau of Statistic of China statis- 2008;Maetal.2008;Pangetal.2008).Alltheseproblems
ticsin2013,from2000to2013,China’saverageannualoil provide a tremendous challenge to deep petroleum
and natural gas consumption increases were 6.1 % and exploration.
14.6 %, respectively, compared to the annual average Withabundantresourcebasesandlowprovedrates,deep
outputincreasesof1.93 %and11.9 %.Deeppetroleum,as petroliferous basins are important for further reserve and
one of the strategic ‘‘three-new’’ fields for the global oil outputincreases(Tuo2002;Zhaoetal.2005;Dai2006,Pang
industry (Zou 2011) as well as one of the most important etal.2007a;ZhuandZhang2009;Sunetal.2010;Pangetal.
developmentareasforChina’soilindustry,formsthemost 2014a). According to Dai (2006), the proved rate of the
important strategically realistic area for China’s oil explorationconcessionsofPetroChinais17.6 %fordeepoil
industry to lead future petroleum exploration and devel- and9.6 %fordeepnaturalgas,farlowerthantheirmid-and-
opment (Sun et al. 2013). All indicate that deep hydro- shallowcounterpartsof39.6 %foroiland14.6 %fornatural
carbon exploration is an inevitable choice toward ensuring gas.Pangetal.(2007a,b)suggestthatWestChinacontains
energy supply and meeting market demands. around45 %oftheresidualpetroleumresourcesofChina,and
After half a century’s effort, gratifying achievements 80 %oftheseresidualresourcesareburiedindeephorizons
have been made in deep petroleum exploration throughout morethan4,500 mbelowthesurface,yetthepresentproved
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Pet.Sci.(2015)12:1–53 3
rateislessthan20 %.Assuch,implementingdeeppetroleum conceptofdeepbasinsdoesnotonlydifferfromscholarto
resource research, tapping deep petroleum and increasing scholar,italsovarieswiththebasinpositionandformation
petroleum backup reserves are urgently needed if we ever characteristics.
wanttorelievethenation’spetroleumshortageandmitigate
energyrisks.Manyscholarshaveinvestigateddeeppetroleum 2.3 Importance of using the same concept and criteria
geologies and exploration (Perry 1997; Dyman et al. 2002; in deep basins
Pang2010;Maetal.2011;Heetal.2011;Wangetal.2012;
Wuetal.2012;BaiandCao2014).Ourstudyinconnection No uniform concept or criteria have been agreed upon by
withthenational‘‘973Program’’(2011CB201100)involvesa scholars either in or out of China with respect to deep
summaryanddescriptionofthedevelopmentandorientation petroliferousbasins,hencepreventingfurtherdevelopment
ofresearchbyscholarsinChinaandelsewherewithrespectto andmutualpromotiononscienceresearch.Forthisreason,
petroleum geology and hydrocarbon accumulation in deep we suggest using 4,500 m as the criterion for deep basins
petroliferousbasins. on grounds of the following considerations:
First, this classification represents a succession to pre-
vious findings. The U.S. Geological Survey and some for-
2 Concept and division criteria of deep basins merSovietUnionscholarsused 4,500 masthe criteriafor
deep basins (Barker and Takach 1992). Chinese scholars,
Deep basins are also called deep formations by some representedbyShi,Dai,andZhaoetal.,alsoused4,500 m
scholars. The definition and criteria of deep petroliferous to demarcate deep formations (Shi et al. 2005; Dai et al.
basins differ from country to country, from institution to 2005; Zhao et al. 2005). Chinese administrations like
institution and from scholar to scholar. Ministry of Land and Resources even issued public docu-
ments that define deep petroliferous basins in West China
2.1 Concept and division criteria of deep basins to 4,500 m. Second, 4,500 m represents the general depth
proposed by overseas scholars at which the hydrocarbon entrapment mechanism of a
petroliferousbasintransitsfrombuoyancyaccumulationto
Sofar,therearetwosetsofdefinitionandcriteriafordeep non-buoyancy accumulation. Above this depth, the poros-
petroliferous basins outside China. One is according tothe ities of the sand reservoirs are generally above 12 %; the
formation depth, i.e., formations within a certain limit of permeabilities are higher than 1 mD; and the pore throat
deptharecalleddeepformations.However,thecriteria for radiiarelargerthan2 lm.‘‘High-pointaccumulation,high-
classifying deep basins also differ from scholar to scholar. stand closure, high-porosity enrichment, high-pressure
Representative criteria include 4,000 m (Rodrenvskaya accumulation’’ (Pang et al. 2014a) normal oil–gas reser-
2001), 4,500 m (Barker and Takach 1992), 5,000 m voirs generally formed under the action of buoyant forces.
(Samvelov 1997; Melienvski 2001), and 5,500 m (Man- Below this depth, to the contrary, ‘‘low-depression accu-
hadieph2001;Bluokeny2001).Anotherisaccordingtothe mulation, low-stand inversion, low-porosity enrichment,
formation age, i.e., for a given basin, formations older in low-pressure stability’’ unconventional oil–gas reservoirs
ageanddeeperarecalleddeepformations(Sugisaki1981). generally formed. To make things easier, we divide a pet-
Table 1 summarizes the criteria used by different institu- roliferous basin into four parts according to the buried
tions and scholars for deep basins from which it is easy to depth, using the criteria accepted by previous scholars:
see that 4,000 and 4,500 m are the criteria accepted by shallow (\2,000 m), middle (2,000–4,500 m), deep
more institutions and scholars. (4,500–6,000 m),andultra-deep([6,000 m).Accordingto
themaximumdepthsofbasins,wedividethemintoshallow
2.2 Concept and division criteria of deep basins basins (\2,000 m), middle basins (2,000–4,500 m), deep
proposed by Chinese scholars basins(4,500–6,000 m),andultra-deepbasins([6,000 m).
Third, deep basins should be classified according to the
Chinese scholars use roughly the same criteria for deep depth rather than incorporating the geological aspects that
petroliferousbasinsastheiroverseascounterparts.Mostof constrainthedepthdistributionofhydrocarbonentrapment.
themusethreeindicators:(1)formationdepth(Wangetal. For example, the fact that oil–gas reservoirs in East China
1994; Li and Li 1994; Tuo et al. 1994; Zhou et al. 1999; basins are commonly shallow while those in West China
Hao et al. 2002; Shi et al. 2005; Dai et al. 2005); (2) basinsarecommonlydeepisattributabletotheirrespective
formation age (Kang 2003; Ma et al. 2007; Ma and Chu unique basin evolution geologies such as the geothermal
2008); and (3) formation characteristics (Tuo et al. 1999a; gradient, reservoir rock type, formation age, and evolution
Wang et al. 2001; Wang 2002; Pang 2010). Table 2 sum- history. These should not form the basis for diverging the
marizes the criteria used for deep basins. Obviously, the criteria for basin depths.
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4 Pet.Sci.(2015)12:1–53
Table1 CriteriafordeepbasinsproposedbyscholarsoutsideChina
Basisfordeepbasins Criteriafordeepbasins Targetedarea Researcherandyear
Formationdepth [4,000m InformerSovietUnion Rodrenvskaya(2001)
[4,500m CaspianBasin
[4,500m IntheUSA
GulfofMexico,USA BarkerandTakach(1992)
[5,000m Samvelov(1997)
WestSiberiaBasin,EastSiberiaBasin Melienvski(2001)
[5,500m SouthCaspianBasin Manhadieph(2001)
Timan-PechoraBasin Bluokeny(2001)
Formationage Stratigraphicallyoldformations IntheUSA Sugisaki(1981)
withlargeburieddepths
Table2 CriteriaofdeepbasinsproposedbyChinesescholars
Basisfordeep Criteriafordeepbasins Targetedareaorparameterfeatures Researcherandyear
basins
Formationdepth [2,500m BohaiBayBasin Qiaoetal.(2002)
[2,800m SongliaoBasin Wangetal.(1994)
[3,500m LiaoheBasin Lietal.(1999)
BohaiBayBasin Tuo(1994)
BohaiBayBasin Zhouetal.(1999)
YinggehaiBasin Haoetal.(2002)
[3,500m EastChinabasins MinistryofLandandResources
(2005)
[4,500m JunggarBasin Shietal.(2005)
Tarim,Junggar,Sichuanbasins Dai(2003)
SichuanBasin Zhaoetal.(2005)
[4,500m WestChinabasins MinistryofLandandResources
(2005)
Formationage& Stratigraphicallyoldwithlargeburied Variesfrombasintobasin Kang(2003),Maetal.(2007),Ma
depth depths andChu(2008)
Formation Formationthermalevolutionlevel R C1.35% Tuoetal.(1999b),Tuo(2002)
o
characteristics Formationthermalevolutionlevelor R C1.35%orformationdepth Wangetal.(2001),Tuoetal.
o
formationpressure overpressure (1999b),Wangetal.(2002)
Formationthermalevolutionleveland R C1.35%orsandstoneformation Pang(2010)
o
tightnesslevel UB12%,KB1mD,YB2lm
3 Exploration for deep oil–gas reservoirs etal.2002).First,majorbreakthroughsindrillingoperation
led to the discovery of a number of oil–gas reservoirs
3.1 Exploration for deep oil–gas reservoirs including a gas reservoir in the Cambrian–Ordovician
across the world Arbuckle Group dolomites at 8,097 m depth in the Mills
Ranch gas field in the Anadarko Basin in 1977 (Jemison
Followingthediscoveryofthefirstdeephydrocarbonfield 1979). From 1980, deep petroleum exploration started to
below 4,500 m in the USA in 1952, deep petroleum extend from onshore to offshore. Examples include a gas
exploration boomed in many countries. Seventy countries fielddiscoveredinPermianKhuffFormationlimestonesat
tried deep exploration (Wu and Xian 2006). Echoing 4,500 m in the Fateh gas reservoir in the Arabian-Iranian
breakthroughs in deep well drilling and completion tech- Basin in 1980, and an oil reservoir at a depth of 6,400 m
niques, a succession of major breakthroughs have been was discovered in the Triassic dolomites of the Villifort-
made in deep hydrocarbon reservoir exploration (Dyman una-Trecate oilfield in Italy in 1984. Recently, major
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Pet.Sci.(2015)12:1–53 5
breakthroughs in deep oil exploitation have been reported According to USGS and World Petroleum Investment
in the deep and ultra-deep waters of the Gulf of Mexico, Environment Database, from 1945 to 2014, the world’s
East Brazil, and West Africa (Bai and Cao 2014). normal petroleum resource has increased from 96 billion
Accordingto IHS data as of2010, 171deep basins and 29 ton in 1945 to 630 billion ton in 2014, the annual average
ultra-deep basins had been discovered out of the 1,186 increase being as high as 8.06 % (Fig. 2a), and the natural
petroliferous basins in the world. These deep basins are gas resource has also increased from 260 trillion m3 in
predominantlysituatedintheformerSovietUnion,Middle 1986 to 460 trillion m3 in 2013, the annual average
East,Africa,Asia-Pacific,NorthAmerica,andCentraland increase being as high as 2.85 % (Fig. 2b). Over the past
SouthAmerica(Fig. 1).Atotalof1,290oil–gasreservoirs years, the world has shown robust momentum for deep
have been discovered in deep basins and 187 oil–gas res- petroleum exploration. The number of oil–gas reservoirs
ervoirs in ultra-deep basins across the world. Break- discovered keeps growing fast (Fig. 3). According to data
throughsarecontinuouslyreportedaroundtheworldinthe provided by Kutcherov et al. (2008), more than 1,000
course of deep exploration. First, the drilling depth con- hydrocarbon fields have been developed at depths of
tinues to increase, the maximum being deeper than 4,500–8,103 m, the original recoverable oil reserve of
10,000 m,asexemplifiedbythedeepestwellwith12,200m which contributes7 % ofthe world’stotal amountand the
drilling depth, SG-3 exploratory well. The deepest oil naturalgasreservemakesup25 %.AccordingtoIHSdata,
reservoir discovered so far is the Tiber clastic rock oil asof2010,forthe4,500–6,000 mdeephydrocarbonfields
reservoir (1,259 m underwater and 8,740 m underground). in the world, the proved recoverable residual oil reserve is
The depth of gas wells continues to increase, and the 83.8 billion ton or 35.5 % of the total recoverable oil
deepest gas reservoir discovered so far (8,309–8,322 m) is reserve,andthenaturalgasis65.9billiontonoilequivalent
a Silurian basin gas reservoir in the Anadarko Basin. or 44.4 % of the total productive natural gas reserve; for
Second, the manageable formation temperature and for- the 6,000 m ordeeper hydrocarbon fields in the world, the
mationpressureindrillingoperationsarealsocontinuously proved recoverable residual oil reserve is 10.5 billion ton
increasing. So far, the highest temperature encountered is or 4.45 % of the total productive oil reserve, and the nat-
370 (cid:3)C and the highest pressure encountered is 172 MPa uralgas is7billiontonoilequivalentor4.7 %ofthe total
(Table 3). productive natural gas reserve (Fig. 4).
0° 30° 60° 90° 120° 150° 180° -150° -120° -90° -60°
90° 90°
Arctic Arctic Ocean
60° E1u01rop2e10 1220002972F0o62r08mer Soviet 22U0043ni20o22n01205 505504503 502 501 507506 601 North America 60° OLcaenadn
30° A 402 401Afri4c08a44M0067id30d2le E3a01st 505809 Asia-Pacific 603 602 30° Deep
0° tlan 403 404 511 Pacific Ocean 706 705 0° petrboalisfeinrsous
tic 405 510 Central and
-30° O 513 512 S70o970u77t0h8 A7m01e7r0i2ca707304 -30°
c 514
ea Indian Ocean
n
-60° -60°
0 1000 2000km
-90° -90°
0° 30° 60° 90° 120° 150° 180° -150° -120° -90° -60°
Europe Former Soviet Union Middle East Africa Asia-Pacific North America Central and South America
101North Sea graben 201 Timan-Pechora 206 northern Carpathians 301 Arabian Basin 401 Ghadames 501 Songliao 508 Indus 601 Cook Bay 701 Barana
102edge of Jarno Scandinavian- 202 Volga - Ural 207 Panta Virginia 302Levant 402 Atlas 502 Bohai Bay 509 Mumbai 602 Gulf of Mexico 702 Santos
Denmark - Poland 203 PreCaspian 208 Carpathian - Balkan 403 Ivory Coast 503 Tuha 510 East Java 603 West Texas Basin 703 Espos
204 MidCaspian 209 Ionian Basin 404 Niger delta 504 Junggar 511 Brunei-Sabah 704 Espiritu Santo
205 Karakum 210 Molasse Basin 405 Tanzania 505 Tarim 512 Bonaparte 705 East Venezuela Basin
406 Nile delta 506 Hokkaido 513 North Carnarvon 706 Llanos - Barinas
407 Western Desert 507 Akita - Niigata 514 Taranaki basin 707Beney
408 Siirt 708 Santa Cruz - Tarija
709 Cuyo
Fig.1 Horizontaldistributionofmajordeeppetroliferousbasinsintheworld
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6 Pet.Sci.(2015)12:1–53
Table3 Geologicalcharacteristicsofworldrepresentativedeepoil–gasreservoirsknownsofar
Feature Name Year Parameters Region
Deepestwell SG-3exploratorywell 1992 Completiondepth KolaPeninsula,
12,200m Russia
Deepestoilreservoir Tiberclasticrockoilreservoir 2009 Burieddepth GulfofMexico
8,740m abyssalbasin,USA
Deepestgasreservoir MillsRanchgasreservoir 1977 Burieddepth WesternInterior
7,663–8,083m Basin,USA
Deephydrocarbonreservoirwith GaenserndorfUbertiefoilfieldHauptdolomit 1977 Porosity35%– ViennaBasin,Austria
highestporosity Formationgasreservoir 38%
Deephydrocarbonreservoirwith Morahydrocarbonreservoir 1981 Porosity2.6%– SuresteBasin,
lowestporosity 4% Mexico
Deephydrocarbonreservoirwith Platanaloilfield4830–Cretaceoushydrocarbon 1978 Permeability SuresteBasin,
highestpermeability reservoir 7,800mD Mexico
Deephydrocarbonreservoirwith WolongheHuanglongstructuralbeltgasreservoir 1980 Permeability SichuanBasin,China
lowestpermeability 0.01mD
Deepgasreservoirwithhighest Satishydrocarbonreservoir,TinehFormationgas 2008 Temperature NileDeltaBasin,
temperature reservoir 370(cid:3)C Egypt
Deepoilreservoirwithlowest SarutayuskoyeoilfieldStarooskolskiyGroupoil 2008 Temperature47(cid:3)C PecholaBasin,Russia
temperature reservoir
Deepgasreservoirwithhighest ZistersdorfUbertief1oilfieldBasalBrecciagas 1980 Pressure172MPa ViennaBasin,Austria
pressure reservoir
Deephydrocarbonreservoirwith AkzharEastoilfieldAsselianVIII(PreCaspian) 1988 Pressure8.4MPa CaspianBasin,
lowestpressure Unithydrocarbonreservoir Kazakhstan
7000 s 600
s e
n ton 6000 metr 500
o 5000 c
milli ubi 400
20 4000 n c
1 o 300
urce, 3000 e, trilli 200
o 2000 c
Res 1000 sour 100
e
R
1945 1950 1960 1970 1980 1990 2000 2014 1980 1990 2000 2010 2014
Time, year Time, year
(a) The evaluation quantity of the world's (b) The evaluation quantity of the world's
conventional oil resources changes with time conventional gas resources changes with time
Fig.2 Worldpetroleumevaluationresultandvariationasafunctionoftime
3.2 Exploration of deep oil–gas reservoirs in China ultra-deep well drilling techniques and equipment,
onshore petroleum exploration has continued to extend
China started deep petroleum exploration from the late toward deep and ultra-deep levels (Sun et al. 2010);
1970s, having discovered a number of large deep oil–gas petroleum exploration has also undergone a transition
fields in the deep parts of some large sedimentary basins from shallow to deep and further to ultra-deep levels. On
including Tarim, Erdos, and Sichuan basins, and made July 28, 1966, China’s first deep well, Songji-6 of Daqing
important progresses in the deep parts of the Daqing, (4,719-m well depth), was completed, marking the tran-
Zhongyuan, Dagang, and Shengli fields in East China’s sition of China’s drilling operation from shallow wells to
petroleum region (Feng 2006; Song et al. 2008; Wu and middle and deep wells, and signaling that China’s petro-
Xian 2006). With the nation’s breakthroughs in deep and leum exploration was turning from shallow toward deep
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Pet.Sci.(2015)12:1–53 7
oirs 350 distributed in Central China and Southern North China.
v 293 China also has a huge stock of ultra-deep petroleum
er 300
s resources, having discovered some ultra-deep basins with
s re 250 243 buried depths of more than 6,000 m, including the Tarim
d ga 200 168 202 193 194 Basin and Songliao Basin. These are mostly located in
n
a 150 Northwest and Northeast China (Fig. 5).
oil China is rich in deep petroleum resources with vast
of 100 81
s 53 roomforfurtherexploration.Accordingtoa2005statistics
mber 50 1 8 6 9 of Shi et al., the deep oil resource within the mineral
u 0 concession of CNPC is approximately 51.5 9 108 t or
N
12 % of the total; the deep natural gas reserve is
4.25 9 1012m3or19 %ofthetotal.ZhuandZhang(2009)
Year suggest that China’s deep petroleum resource reserves are
extremely non-uniform and mostly found in Xinjiang. In
Fig.3 Number of deep oil–gas reservoirs discovered in the world
the Junggar Basin, the middle–shallow and deep oil geo-
anditsvariationasafunctionofyear
logicalresourcesare9.7 9 108torapproximately18 %of
the basin’s total amount; the deep natural gas resource is
levels. From 1976, China’s petroleum exploration mar- 2,081 9 108m3orapproximately32 %ofthebasin’stotal
ched toward ultra-deep levels. On April 30, 1976, China’s
amount. Pang (2010) discovered after studies that the Ta-
first ultra-deep well, Nuji well in Sichuan (6,011 m well
rim Basin has the richest oil resources in the deep part at
depth), was completed, marking the entry of China’s 33.7 9 108 t or 56 % of the basin’s total oil resource,
petroleum exploration into ultra-deep levels (Wang et al. natural gas resources in the deep part at 29,244 9 108 m3
1998). So far, China has drilled deep wells in 15 large
or 37 % of the basin’s total natural gas resource. Statistics
basins with sedimentary thicknesses larger than 5 km
indicate that China’s deep petroleum resource is 30,408
(Pang 2010). Of the 176 deep exploratory wells drilled in
million ton, which is 27.3 % of the nation’s total oil
the Jizhong Depression (the average well depth is
resource (Fig. 6a); its deep natural gas resource is 29,120
4,521 m), 37 have yielded industrial petroleum flows. The billionm3,whichis49.2 %ofthenation’stotalnaturalgas
exploratory well success rate has reached 21.4 % (Tuo
resource (Fig. 6b). Since 2000, China’s petroleum explo-
2002). Of the 156 pay zone well intervals tested in the
ration has continued to extend toward deep and ultra-deep
Tarim Basin, 58 have their bottom boundaries deeper than
levels. In the Junggar Basin, the ratio of deep exploratory
5,000 m (Pang 2010). According to statistics, as of 2010,
wells increased from 3 % in 2000 to 15 % in 2013
of the 47 petroliferous basins in China, seven deep basins
(Fig. 7a). In the Tarim Basin, this ratio increased from
have been discovered, out of which 210 deeper than
65 %in2000to92 %in2013(Fig. 7b).Theratioofnewly
4,500 m oil–gas reservoirs have been identified. Shallow
increased petroleum reserves in deep formations has also
basins at a depth of 2,000 m or shallower are predomi-
continued to rise. In the Tarim Basin, the ratio of deep oil
nantly found in China’s Inner Mongolia and Tibet;
increasedfrom66 %in2000to92 %in2013(Fig. 8a);the
2,000–4,500 m middle deep basins are typicallylocated in
ratioofdeepnaturalgasalsoincreasedfrom66 %in2004
the seas of East China; 4,500–6,000 m deep basins are
to 92 % in 2013 (Fig. 8b).
4.45% 4.71%
35.54%
<4500m 50.39% <4500m
44.36%
60.01%
4500-6000m 4500-6000m
>6000m >6000m
(a) The depth distribution of the world recoverable oil reserves (b) The depth distribution of the world recoverable gas reserves
Fig.4 Distributionofworldrecoverableoilandgasreservesatmiddleanddeepdepthsofpetroliferousbasins
123
8 Pet.Sci.(2015)12:1–53
Hailar Basin Songliao Basin
Junggar Basin Haerbin
Urumqi
Turpan Hami Basin
Tarim Basin Erlian Basin Shenyang
Ejinaqi-
Dunhuang Basin Yingen Basin Beijing
Bohai Bay Basin
Qaidam Basin
Xining Erdos Basin
Qinshui Basin
Qiangtang Basin
South Yellow Sea Basin
Zhengzhou
Southern North China Basin
Okinawa Trough
Sichuan Basin
Lhasa Chengdu Wuhan East China Sea Basin
Chuxiong Basin Pearl River Mouth Basin
Kunming Fuzhou
Legend
Yinggehai Basin
Shallow basin<2000m Guangzhou
Middle basin 2000m-4500m
Pearl River Mouth Basin
Deep basin 4500m-6000m
Ultra deep basin>6000m Yinggehai Basin
South China Sea Islands
Fig.5 DepthclassificationandhorizontaldistributionofpetroliferousbasinsinChina
4 Geological features of deep oil–gas reservoirs middle or shallow counterparts. Many scholars (Zap-
paterra 1994; Dyman and Cook 2001; Liu et al. 2007a,
Compared with middle or shallow petroliferous basins, b; Wang et al. 2012) have examined deep oil–gas res-
deep basins have large buried depths and the features of ervoirs. Table 4 lists some typical hydrocarbon fields
high temperature, high pressure, low porosity, low (reservoirs) discovered in deep petroliferous basins in
permeability, complex structural styles, and highly the world, from which we can observe their differences
variable sedimentary forms. These special properties and varieties in terms of formation age, lithology,
have been responsible for the unique characteristics of buried depth, porosity, pressure, petroleum phase, trap
deep basin oil–gas reservoirs compared with their type, and basin type.
27.26%
35.05% 14.20%
49.23%
36.57%
37.68%
<2000m 2000-4500m >4500m <2000m 2000-4500m >4500m
(a) The depth distribution of oil prospective resource (b) The depth distribution of gas prospective resource
Fig.6 DepthdistributionofpetroliferousbasinresourcesinChina
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Pet.Sci.(2015)12:1–53 9
Fig.7 Depthsofexploratory Number of exploratory wells
wellsdrilledintheJunggarand
120
Tarimbasins.aNumberand
(cid:33)6000 m
depthofexploratorywells 3%
100 4500-6000 m
drilledintheJunggarBasinover
time,bNumberanddepthof (cid:31)4500 m 4%
80
exploratorywellsdrilledinthe 7% 11%
6% 7%
TarimBasinsince2000
60 5%
16%15%
40 3% 3% 12% 13%
0
20
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
(a)
Number of exploratory wells
250
>6000 m 79% 92%
97%
200 4500-6000 m
<4500 m 74% 97%
150 95%
89%
80%
100 65% 80% 80% 87% 79% 78%
50
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
(b)
4.1 While oil–gas reservoirs have been discovered basins contain far more deep petroleum resources since
in many types of deep petroliferous basins, most when they reached the same buried depth, they had lower
have been discovered in low heat flux deep basins pyrolysis temperatures, and source rocks were richer in
residual organic matter and hence had greater ability to
Oil–gasreservoirshavebeendiscoveredinalltypesofdeep generate and preserve hydrocarbon. Figure 11 compares
petroliferous basins (Fig. 9).Based on the basin classifica- the deep hydrocarbon potentials of source rocks in basins
tionsystemofIngersoll(1995),BaiandCao(2014)classi- with different geothermal gradients in China as a function
fied 87 deep petroliferous basins into seven groups: of depth, from which we can observed that ‘‘hot’’ basins
continental rift, passive continental marginal, foreland, expelled less hydrocarbon indicating they make up a
interiorcraton,fore-arc,back-arc,andstrike-slipbasins,of smaller proportion of deep petroleum resources than their
which the passive continental marginal basins (25) and ‘‘cold’’counterparts.Asthegeothermalgradient increases,
foreland basins (41) are the richest in deep petroleum, fol- theratioofdeeppetroleumresourcesreduces.Accordingto
lowed by the rift basins (12). These three types contribute geothermalgradientrecordsof405deepoil–gasreservoirs
47.7,46.4,and5.6 %oftheworld’sdeepprovenandprob- acrosstheworld,318 %or78.5 %werediscoveredindeep
able (2P) recoverable petroleum reserves. The deep 2P basins with geothermal gradients of 1–2 (cid:3)C/100 m; 79 %
recoverable petroleum reserves in the back-arc basins (2), or19.5 %werediscoveredindeepbasinswithgeothermal
strike-slipbasins(3),andinteriorcratonbasin(1)contribute gradients of 2–3 (cid:3)C/100 m; and 8 % or 2 % were discov-
merely0.3 %oftheworld’stotal(Fig. 10). ered in deep basins with geothermal gradients larger than
Asamatteroffact, thedistributiondivergencesofdeep 3 (cid:3)C/100 m (Fig. 12). In China, the geothermal gradient
oil–gas reservoirs in petroliferous basins are essentially increases from the west toward the east. The number and
decided by the geothermal gradients of the sedimentary reserves of deep oil–gas reservoirs discovered in West
basins. Compared with the higher geothermal gradient ChinabasinsisfarlargerthanthatdiscoveredinEastChina
counterparts, lower geothermal gradient sedimentary basins (Fig. 13).
123
10 Pet.Sci.(2015)12:1–53
Freisge.rv8esPirnovtehdedTeaerpimoiBlaasnidngas nes35000 >4560000-06m000m 79%
n
discoveredeachyearsince o30000 <4500m
2000.aDepthdistributionof d t
n
pBraosvineddoisiclorveseerervdeesaicnhthyeeaTrarim housa2205000000 66% 86% 78% 75% 80%89% 96% 97% 92% 92%
since2000,bDepthdistribution n-t
ofprovednaturalgasreservesin e15000 80%
theTarimBasin s, t 95%
ve10000 80%
er
s
e 5000
Oil r
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
(a)
>6000m
e 4500-6000m
etr 20000
m <4500m 80% 80%
oncubic 15000 80% 78% 79%75% 89% 96% 97%97% 92%
milli
d 80% 86%
e 10000 66%
dr
n
u
h
es, 5000
v
er
s
e
s r 0
a
G 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
(b)
4.2 While many types of petroliferous traps are Desert Basin and Green River Basin, and China’s Erdos,
developed in deep basins, oil–gas-bearing features Sichuan, and Songliao basins, people have become more
in deep basin traps are arousing increasing interestedintheseunconventionaloil–gasreservoirs.First,
attention these reservoirs have completely different genesis com-
paredwithconventionalreservoirs,andtheirdiscoveryhas
Like their middle–shallow counterparts, deep basins also brought on a novel petroleum exploration field. Second,
contain a variety of traps which, according to the con- these reservoirs are widely and continuously distributed
ventional trap classification, include tectonic traps, strati- withvastresourcepotentialsandgreatscopeforpetroleum
graphic traps, lithological traps, structural-lithological exploration. Third, these reservoirs formed inside deep
traps, structural-stratigraphic traps, and lithological-strati- basin traps between the buoyancy accumulation threshold
graphictraps.Differenttypesoftrapsdiffersignificantlyin of a petroliferous basin and the basement of the basin.
terms of their reserves. After a statistical analysis on 837 Their buried depths were quite large, but can be very
deep oil–gas reservoirs in the USA, Dyman et al. (1997) shallowatpresentasaresultofsubsequenttectonicevents
discoveredthatstructuraltrapsandcombinationtrapsmake in the basin. Deep basin traps are a special type of
up as much as 66.9 %. Only in Anadarko and California hydrocarbon trap in which the reservoir media have
basinsaretheremorelithologicaltrapsthanstructuralones porosities smaller than 12 %, permeabilities smaller than
(Fig. 14). Bai and Cao (2014), after summarizing the trap 1 9 10-3 lm2, and throat radii smaller than 2 lm.
types and reserves of the world’s deep oil–gas reservoirs, Hydrocarbon was not subject to buoyancy in its accumu-
discoveredthatstructuraltrapshave73.7 %oftheworld’s lation, thus making it possible tospreadcontinuously. The
deep recoverable 2P petroleum reserves, with structural- more developed the sources rocks were in a deep basin
lithological traps and stratigraphic traps contributing trap, the more continuous the reservoirs were distributed
21.9 % and 4.4 %, respectively (Fig. 15). close to the source rocks and the richer the petroleum
Recently,withthediscoveryoftight,continuousoil–gas resources they provide. Figure 16 gives a typical concep-
reservoirs in Canada’s Alberta Basin, the USA’s Red tualmodelandshowsthedifferenceaboutthedevelopment
123