Reservoir-forming condition analysis and favorable … · ENERGY EXPLORATION & EXPLOITATION·...

ENERGY EXPLORATION & EXPLOITATION · Volume 31 · Number 3 · 2013 pp. 381–394 381

Reservoir-forming condition analysis and favorable zoneprediction for the shale gas in the Upper Paleozoic

Taiyuan Formation in the Ordos Basin

Shaobin Guo* and Yigang WangSchool of Energy Resources, China University of Geosciences, Beijing 100083, China

*Author for corresponding. E-mail: [email protected]

(Received 25 January 2012; accepted 18 November 2012)

AbstractShale gas is a hydrocarbon gas occurring in organic-rich argillaceous shale in afree and adsorbed state. The shale in shale gas reservoirs is source rock and alsocontainer rock, which is different from the situation in conventional gasreservoirs; the gas content in shale is mainly related to the abundance, type, andevolution degree of organic matter. The Taiyuan Formation in the Ordos Basinis marine-continental transitional sediments; the argillaceous shale of theTaiyuan Formation has features such as high organic matter abundance and highthermal evolution degree and has better reservoir-forming conditions, comparedwith the shale gas reservoirs outside China. The argillaceous shale in theTaiyuan Formation strata is mixed with thin gas-bearing sand layers, whichindicates a high hydrocarbon-generating potential of the argillaceous shale.According to the main reservoir-forming conditions of shale gas, it is predictedthat the favorable zones of shale gas in the Taiyuan Formation are primarilylocated in areas such as the northwestern corner of the Tianhuan Depression, thenortheastern corner of the Shanbei Slope Belt, and the central and southern partsof the Ordos Basin. With the rapid progress in shale gas exploration andexploitation technologies, the shale gas in the Taiyuan Formation in the OrdosBasin has become an important exploration target because of its huge potential.

Keywords: Ordos Basin; Marine-continental transitional facies; Organic carboncontent; Vitrinite reflectance; Favorable zone prediction

1. INTRODUCTIONShale gas is a hydrocarbon gas occurring in organic-rich argillaceous shale in a freestate and adsorbed state and its reservoir formation and distribution have geologicalcharacteristics such as short migration distance, multiple sealing mechanisms, hiddenaccumulation and reservoir formation, and gas-saturated strata. Their self-generation,self-storage, and adsorption mechanisms and the large-scale accumulation areimportant geological features of shale gas (Law and Curtis, 2002; Curtis, 2002; Mavor

and Corporation, 2003; Zhang et al., 2004; Bowker, 2005; Zhang et al., 2008). Theexploration and exploitation of shale gas has been successful in North America, wherecommercial exploitation has been achieved in multiple basins in Michigan, Indiana,and other regions of the United States (USA) (Montgomery et al., 2005; McCallister,2006; Pollastro et al., 2007; Liu et al., 2010). The total shale gas output for the USAreached 1, 378 ∞ 108 m3 in 2010, accounting for about 23% of total natural gas outputin the whole USA, and is expected to be (2,600−2,800) ∞ 108 m3 in 2015, accountingfor about 1/3 of the country’s total natural gas output. Therefore, increasing attentionhas been paid to the huge potential of shale gas.

The Ordos Basin is an important oil- and gas-bearing basin in China, with a mainbody area of more than 200 thousand square kilometers (Liu et al., 2009; Sun et al.,2009). It can be divided into six first-level tectonic units based on the currenttectonic form, basement nature, and tectonic feature of the basin: the Yimeng Upliftin the north, the fault fold belt on the western margin, the Tianhuan Depression inthe west, the Shanbei Slope in the center, the Weibei Uplift in the south, and the Jinxi Flexural Fold Belt in the east (Fig. 1). There are four sets of effective

382 Reservoir-forming condition analysis and favorable zone prediction for the shale gas in the Upper Paleozoic Taiyuan Formation in the Ordos Basin

Yimeng Uplift

HangjinqiErdos

2

4

6

1012

8 1414

16

18

12

14

1416

18

14

10 6

14

16

8

6

10

6

8

4

10

10

8

8

6

6

10

10

12

86

42

12

14

12

4

42

1012

8

14

18

24 2220 18

16

262830

3234

3638

16

10

Zhunger

Fugu

ShenmuB

Yellow

JinxiF

oldB

elt

Daning

Yanchang

Snde Lisni

Flexural

Fuxian

Hejin

ChengchengWeibei Uplift

Chunnua

Pingliang

Qingyang

Huanxian

Dinguian Jianguian

Wushenqi

Tian

Huan

Depression

Wunai

Shizulshan

Yinchaun

Wuznong

A

Xi Y

uan Thrust S

tructure Belt

Etuoke

Slo

pe

Bei

Sha

n

Yel

low

Riv

er

River

20 km0

Figure 1. Structural framework and shale thickness contour map of Taiyuanformation in Ordos basin.

hydrocarbon source rock grown vertically from top to bottom: Lower Paleozoicmarine carbonate rock type hydrocarbon source rock, Upper Paleozoic marinecarbonate rock type hydrocarbon source rock, Upper Paleozoic Permo-Carboniferous coal and dark argillite type hydrocarbon source rock, and MesozoicTriassic Yanchang Formation containing lacustrine dark argillite type hydrocarbonsource rock (Xu and Bao, 2009). Large conventional gas fields, including Jingbian,Sulige, Wushenqi, Yulin, and Daniudi, have been discovered so far, which indicatesthat the Upper Paleozoic shale gas in the Ordos Basin will have significantexploration potential. We studied the reservoir-forming conditions and explorationpotential of shale gas in the formation with the Upper Paleozoic Lower PermianTaiyuan Formation in the Ordos Basin as the target.

2. RESERVOIR-FORMING CONDITION ANALYSIS FOR THE SHALE GASIN THE TAIYUAN FORMATION IN THE ORDOS BASIN2.1. Shale sedimentary facies and shale distributionAfter the Middle Carboniferous Epoch, sea water had extended from the east, west,and south to the north with the settlement of the basin. Since the Late Taiyuan Age,owing to tectonic uplift, there had been deltaic deposits entering the tidal flat settingin the epicontinental seas in the northwest, north, northeast, and southwest to form aninterlaced marine-terrestrial sedimentary framework.

The Taiyuan Formation continuously settled onto the Benxi Formation, and thestrata spread in most areas of the basin. In the Taiyuan Formation, the areas withthicker argillite layers are located in the Tianhuan Depression district and the areas tothe north of Suide and Shenmu; the argillite thickness in these areas is more than 40 mand the central part of the Tianhuan Depression has an argillite thickness of more than50 m; the argillite thickness in the central part of the basin is generally 10−30 m(Fig. 1). The lithology of the Taiyuan Formation is mainly micritic biolithite, grayblack-black argillite, arenaceous argillite, and gray white quartz sandstone, as well ascoal seam (Fig. 2).

ENERGY EXPLORATION & EXPLOITATION · Volume 31 · Number 3 · 2013 383

Figure 2. Shale contrasting profile of Taiyuan formation in Ordos basin (ProfilePosition: Line A-B in Fig. 1).

GR

2803960 3460

3170

3180 30302320

2330

2340

2350

3040

3050

3060

31903470

3980

4000

300

330

340

R1 RT GR E7 RT GR SU7 RT GR SH164 RT GR T17 RT GR SHEN4 RT

2.2. Geochemical characteristics2.2.1. Organic matter abundanceOrganic matter abundance is the most fundamental indictor to evaluate hydrocarbonsource rock (Meng et al., 2012). The organic matter abundance of hydrocarbon sourcerock is generally expressed by the contents of total organic carbon (TOC), chloroformbitumen “A” and total hydrocarbon (HC), in which the total organic carbon is aparameter that controls the last two and also a basic parameter for oil and gas resourceevaluation (Houseknecht and Weesner, 1997; Jin et al., 2001; Carr et al., 2009;Li et al., 2010). The total organic carbon content is also used as the main indicator oforganic matter abundance in shale gas evaluation.

The total organic carbon content is universally higher in the argillite of the TaiyuanFormation in the Ordos Basin (Fig. 3, Table 1). Statistical analysis shows that the


20

18

16

14

12

8

10

Num

ber

6

4

2

00–1 1–2 2–3 3–4 4–5 5–6 6–7 7–8 8–9 9–10 >10

0

Number

Accumulated frequency

TOC (%)

20

40

Acc

umul

ated

freq

uenc

y (%

)

60

80

100

Figure 3. The distribution frequency of measured TOC of the Taiyuan Formationshale in the Ordos Basin.

Table 1. Shale TOC testing data of Taiyuan formation.

Measured TOC %__________________________________________Well & Outcrop Lithology Min Max AverageM4 Shale 1.01 2.08 1.65HT1 Shale 0.68 5.57 2.16FT1 Shale 0.75 21.89 6.91DT1 Shale 2.33 4.22 3.13Outcrop_1 Shale 0.51 4.5 1.58Outcrop_2 Shale 2.81 11.69 7.31

* outcrop_1: Chengjiajiang outcrop;

outcrop_2: Palougou outcrop;

average TOC is 3.5%, with samples with TOC > 1.0% accounting for more than 75%of total samples and those with TOC > 2.0% accounting for more than 50% of totalsamples. Influenced by the sedimentary environment, the horizontal change in TOCcontent in the argillite of the Taiyuan Formation shows a gradual ascending trend fromwest to east in the basin, and the TOC content is higher in local northern areas of thebasin and its northeast; the TOC content in the main body of the basin is generallymore than 1.0% (Fig. 6).

The TOC of gas-generating shale in the five basins in North America (i.e.,Michigan Basin, Appalachian Basin, Fort Worth Basin, San Juan Basin, and IllinoisBasin) was generally 0.3%−24%, so we thought that 0.5% of TOC in argillaceousshale can be used as a lower limit of gas-generating shale and the relatively favorableTOC in gas-generating shale should be higher than 2.0%. In terms of organic matterabundance, the argillite of the Taiyuan Formation in the Ordos Basin belongs toargillaceous shale with relatively high organic matter abundance.

2.2.2. Organic matter typeThere are many methods for evaluation of organic matter types, including use of theatomic ratio of kerogen, the rock pyrolysis parameter, the kerogen type index, and thecarbon isotope δ13C indicator of kerogen. The rock pyrolysis parameter method isused to calculate the hydrogen index (S2/TOC, IH) and the oxygen index (S3/TOC,IO), respectively, according to the adsorbed hydrocarbon (S1), kerogen pyrolyzedhydrocarbon (S2), and carbon dioxide (S3) determined from rock pyrolysis, so as toidentify the organic matter type in oil-generating rock.

Based on the rock pyrolysis method, the organic matter in argillite was categorizedaccording to the hydrogen index and the oxygen index, and the organic matter in theargillite of the Taiyuan Formation was found to contain mainly Type I and Type II1and a little Type II2 and Type III (Fig. 4).


300

250

200

150

100

50

00 50 100

Ol (mg.CO2/g.TOC)

HI (

mg.

HC

/g.T

OC

)

150

III

III2

II1

200

Benxi FMTaiyuan FMShanxi FM

Figure 4. Graph of organic matter type classified by HI/OI in the Ordos Basin.

2.2.3. Thermal evolution degree of organic matterThe thermal evolution degree of organic matter (i.e., the maturity of organic matter) isan important parameter to characterize the hydrocarbon-forming effectiveness andproduct nature of organic matter.

Vitrinite reflectance is also called vitrain reflectance (Ro), and because it is afunction of temperature and effective heating time and has irreversibility, it is one ofthe best parameters to identify the stage of coalification. Dow (1977) proposed that thelogarithm of vitrinite reflectance (1ogRo) has a linear relationship with the burialdepth. According to statistical results of data on the vitrinite reflectance of the organicmatter in the Upper Paleozoic argillite in the Ordos Basin, we conducted a regressionanalysis to determine the relationship between vitrinite reflectance and burial depth ofthe organic matter in the Upper Paleozoic argillite (Fig. 5) and obtained the followingexpression:

The maturity of organic matters in the argillite of the Upper Paleozoic TaiyuanFormation in the Ordos Basin is 1.5% on average, and the maturity of organic matteris higher along the Qingyang, Huachi, Wuqi, and Jingbian districts, with its maximumreaching 2.0%, and decreases gradually toward the perimeter (Fig. 6).

2.3. Physical properties of argilliteShale gas is a kind of self-generating, self-storage natural gas resource, and itscontainer rock is organic-rich (argillaceous) shale (i.e., argillaceous hydrocarbonsource rock).

The lower argillite of the Taiyuan Formation is pure in quality, slightly light incolor, and hard and brittle. The upper argillite is primarily black, contains rich organic

R eH

o = −

2081

2611


500

1000

1500

2000

2500

H (

m)

3000

3500

4000

4500

0 1

Ro (%)

y = 2611.In(x) + 2081R2 = 0.898

2 3

Figure 5. Regression curve of Ro and buried depth of organic matter.

matter, is hard owing to the contained silt, and has a high content of pyrite, which ismostly crystal-like. After being weathered, the argillite is mostly fragment-like and itscolor turns red brown. The argillite of the Taiyuan Formation has a high organic mattercontent and has coal seams in between locally.

X-ray diffraction analysis of total-rock minerals shows that the argillite of theTaiyuan Formation in the Ordos Basin has an average quartz and feldspar content of54%, an average clay mineral content of 37.6%, and an average content of otherminerals of 8.4% (Fig. 7).

The clay minerals include mainly kaolinite (57.1%) and illite (25.5%) and also alittle chlorite (8.9%) and mixed-layer illite/smectite (8.5%) (Table 2). The argillitecontains rich organic matter. The argillite has developed micropores with commonly


Yimengi Uplift

WunaiHangjinqi

4.0

3.0

1.0 2.0

2.0

1.6

2.0

1.43.0 1.2 8.0

1.2

8.07.0

6.0

3.02.0

2.0

2.0

2.0

5.06.07.0

2.02.0

3.0

8.0

9.0

8.0

9.0

2.0

2.0

1.0

9.0

10.0

2.0

2.0

1.0

0.5

4.0

1.6

2.02.01.0

0.5

2.0

2.0

2.0

0.5

2.0

2.0

1.8

1.6

1.8

1.8

1.0

2.0

2.0

2.02.0

2.0

2.0

3.0

2.0

1.2

1.4

2.0

0..6 8.0 1.2

1.2

0.51.8

1.8

2.0

1.4

1.2

1.0

1.0

2.0

1.2

1.0

1.6

1.8

2.0

1.0

2.20

1.0

2.0

0.5

2.0

2.0

1.0

1.2

1.2

8.0

2.0

2.0

2.0

2.0

1.02.0

1.6

5.0

6.0

7.0

9.0

10.0

6.0

Etuoke

Wuznong

Yinchuan

Shizulshan

Riv

er

Wushenqi

Erdos

Zhunger

Fugu

Shenmu

Yellow

River

JinxiF

lexuralF

old

Daning

Hejin

0 20 km

Chengcheng

Chunnua

Weibei Uplift

Qingyang

Huanxian

Wuqi

Yanchang

1.4

1.4

1.4

SuideS

lope

Fnxian

Bei

Sha

n

Dinguian

Tian

Huan

Xi Y

uan Thrust S

tructure Belt

Depression

Pingliang

Belt

Figure 6. Contour map of TOC and Ro of the Taiyuan Formation shale in the OrdosBasin.

seen denuded pores, and microfissures formed by clay minerals are also moredeveloped (Fig. 8).

The average porosity of the argillite samples of the Taiyuan Formation was 4.66%(with a 0.66% minimum and a 9.12% maximum), establishing their low porosity; andthe average permeability of the argillite samples of the Taiyuan Formation was 0.129∞ 10−3 µm2 (with a 0.00052 ∞ 10−3 µm2 minimum and a 0.37 ∞ 10−3 µm2 maximum).


Table 2. Measured data of shale clay minerals of the Taiyuan Formation.

Sample no. Depth I,% K,% C,% I/S,%LL8B outcrop_1 17 63 0 20LL−9 outcrop_1 26 16 40 18C−2 outcrop_1 75 25 0 0C−3 outcrop_1 15 55 0 30PLG−9 outcrop_2 37 50 10 3P−1 outcrop_2 12 83 5 0P−3 outcrop_2 12 84 4 0P−4 outcrop_2 20 77 3 0S6−4 2188.56 18 59 13 10Y14−4 2282.97 36 36 11 17Qi2−3 2563.80 21 69 8 2Zhao8−6 2901.19 6 81 10 3Y36−4 3031.58 42 36 11 11Sh247−4 3173.43 20 65 10 5

Figure 7. Ternary diagram of shale mineral content of the Taiyuan Formation.

100quarts + feldspar

Clay mineralsOther minerals100

100

80

80

80

60

60

60 40

40

40

20

20

20

0

0

0

3. FAVORABLE ZONE PREDICTION OF THE SHALE GAS3.1. Gas contentShale gas primarily includes adsorbed gas and free gas; the adsorbed gas content isdirectly obtained from desorption of gas-bearing shale samples in general and can alsobe indirectly obtained from an isothermal adsorption experiment. Through theisothermal adsorption experiment, the Langmuir volume (the gas content of thesample under infinite pressure) and the Langmuir pressure (the pressure correspondingto the gas content of the sample equal to half of the Langmuir volume) were obtainedfirst, and then the equation Ga = GLPL/(P+PL) (where Ga is the calculated adsorbedgas content under the stratum condition, GL is the Langmuir volume, PL is theLangmuir pressure, and P is the stratum pressure) was used to calculate the adsorbedgas content of shale under the stratum pressure condition. Experiments have provedthat the adsorbed gas content measured has a very good correlation with thatcalculated through the isothermal adsorption experiment (Pan et al., 2011). There wereno available measured data for the adsorbed gas content in the shale of the Taiyuan


(a) (b)

(c)

Figure 8. Shale SEM photograph of the Taiyuan formation. (a) spherical carbonchips; (b) albite with dissolved pore; (c) flaky kaolinite distributed in illite-smectite

mixed layer.


Formation in the Ordos Basin, so we referenced other research results and used thecalculated adsorbed gas content that is corrected to substitute for the actual adsorbedgas content.

Organic matter content is an essential factor that influences shale gas enrichment,and it determines the quantity of shale gas generated and directly influences the gascontent in shale. Since the organic matter in shale has an important adsorption functionon the gas, a large quantity of gas in the gas-bearing shale is adsorbed to the kerogensurface in an adsorption state. Therefore, high TOC means a high quantity of gasgenerated and a large amount of adsorbed shale, yielding a positive correlationbetween the adsorbed gas content and total organic carbon content in argillaceousshale. Experimental data show that there is a good correlation between the adsorbedgas content and total organic carbon content in the argillaceous shale of the TaiyuanFormation in the Ordos Basin (Fig. 9).

The adsorbed gas content is directly related to the TOC content in the argillaceousshale, so the horizontal change of the adsorbed gas content has a strong correlationwith that of the TOC content: The adsorbed gas content in the argillaceous shale of theTaiyuan Formation is 1.58 m3/t on average (ranging from a minimum of 1.01 m3/t to amaximum of 2.79 m3/t) and increases gradually from the basin center to the basinperimeter; the maximum adsorbed gas content occurs in Shenmu and Fugu districts inthe northeastern corner of the basin and the adsorbed gas content is relatively high inlocal areas to the northwest of Suide in the middle eastern part of the basin.

The free gas in shale has an occurrence state in strata similar to that of conventionalnatural gas, so the free gas content in shale can be calculated with the equation forconventional natural gas. Li et al. found that when the burial depth of shale is less than1,500 m, the adsorbed gas content is more than the free gas content in the shale gas; andwhen the burial depth of shale is more than 1,500 m, the free gas content is more thanthe adsorbed gas content in the shale gas. Therefore, the total average gas content in theorganic-rich shale of the Taiyuan Formation is not less than 2.0 m3/t, which is largerthan the lower limit for viable shale gas exploitation in North America (0.8−1.0 m3/t).

Figure 9. Correlation between TOC and adsorption gas.

4

y = 0.107x + 1.330

R2 = 0.8543

2

Ads

orpt

ion

gas

(m3 /

t)

1

00 2 4 6

TOC (%)8 10 12 14


3.2. Resource potential evaluationAll of the six shale-gas-reservoir-forming elements (i.e., generation, storage, coverage,migration, accumulation, and conservation) are concentrated in the same argillaceousshale layer and a great amount of hydrocarbon gas stays and accumulates inhydrocarbon source rock; therefore, shale gas has relatively simple reservoir-formingcontrol factors and can form a huge resource.

Compared with the argillaceous shale in the basins of the USA, from which shale gashas been successfully exploited (Zhao et al., 2008; Zhang et al., 2008), the argillaceousshale of the Taiyuan Formation in the Ordos Basin similarly has good reservoir-forminggeological conditions (Table 3). Organic-rich argillaceous shale is widely distributed inthe Taiyuan Formation in the Ordos Basin, is thick (generally about 10−40 m), has a highorganic matter abundance (with a TOC content of 0.51%−20%), a high evolution degree(Ro > 1.0%), and a very strong hydrocarbon-generating capability, and belongs tofavorable hydrocarbon source rock. Oil and gas exploration in Ordos proves that the tightsandstone sandwiched in the argillaceous shale layers of the Taiyuan Formation has avery good gas-bearing property, which indicates that the argillaceous shale of theTaiyuan Formation has a strong hydrocarbon-generating potential. Moreover, most of thegenerated natural gas stays in the argillaceous shale strata by dint of the adsorbability andlow permeability of the argillaceous shale strata, so the shale gas in the TaiyuanFormation in the Ordos Basin has a good resource potential.

3.3. Favorable zone predictionNormally, large- and medium-scale gas fields are distributed in the gas-generatingcenter of gas source rock and its perimeter (Wang et al., 2005), and the hydrocarbon-generating capability and quantity of the hydrocarbon source rock are closely relatedto the thickness, organic carbon content, and thermal evolution degree of theargillaceous shale. With the content, type, and thermal evolution degree of organicmatter in argillaceous shale, and the thickness of argillaceous shale, etc.comprehensively considered, it is predicted that the favorable zones of shale gas in the

Table 3. Parameter contrast between American shale gas reservoirs andTaiyuan formation.

OrdosBasin Appalachia Michigan Fort Worth San Juan Taiyuan FMstratum D2−3 C2−C3 C K2 P1TOC (%) 0.5~23 0.3~24 1~4.5 0.45~2.5 0.51~21.9Ro(%) 0.4~1.3 0.4~1.6 1.0~1.4 1.6~1.88 1.0~2.0Natural gas origin pyrolysis pyrolysis pyrolysis pyrolysis pyrolysis

BiogenicShale Thicknes (m) 60~480 49 92~152 152~579 10~50Depth (m) 0~1200 50~500 1982~2592 1200~3500Production (108 m3) 10~40 500 8490

(annual (Total (Total production) production) production)


Taiyuan Formation in the Ordos Basin are mainly located in areas such asthe northwestern corner of the Tianhuan Depression, the northeastern corner of theShanbei Slope Belt, and the central and southern parts of the basin (figure not shown).

With continuing progress in exploration technologies, the shale gas in the TaiyuanFormation may become one of the important targets in future natural gas explorationand exploitation in the Ordos Basin. Because argillaceous shale has low porosity andpoor permeability, container rock transformation must be conducted for shale gasproduction. The clast components of the argillaceous shale of the Taiyuan Formationare mainly bristle minerals including quartz, which are quite favorable to fracturingtransformation of container rock. Furthermore, a major breakthrough has beenachieved for tight sandstone gas exploration of the Ordos Basin, during which the shalegas exploration in the deep part can be concurrently conducted. Li et al. suggested thatthe organic-rich argillaceous shale in alternating marine-continental and continentalcoal measure strata has a small single-layer thickness but has symbiotic conditionswith tight sandstone gas and coal seam gas, making it realistic to develop multiple-layer joint-exploitation technologies for multiple types of natural gas resourcesincluding shale gas and tight sandstone gas (Li et al., 2009).

4. CONCLUSIONSBased on our analysis, we conclude the following:

(1) The argillaceous shale of the Taiyuan Formation in the Ordos Basin has alarge vertical accumulation thickness and a wide horizontal distribution overa certain scale, and it has a high organic matter abundance with an averagetotal organic carbon content of more than 1.0%. The organic matter types aremainly saprohumolith and humosapropelic; the thermal evolution degree oforganic matter is high with an average Ro reaching more than 1.5%, and itbelongs to the mature-high maturity stage, is favorable to gas generationthrough organic matter pyrolysis, and meets the fundamental geologicalcondition for shale-gas-reservoir formation.

(2) The argillite of the Taiyuan Formation is mainly organic-rich black argillite,and the clay minerals include mainly kaolinite and illite and are primarilycomposed of bristle minerals including quartz, which are favorable totransforming the permeability of argillaceous shale container rock throughfracturing or other methods.

(3) Compared with the main shale gas reservoirs outside China, the argillaceousshale of the Taiyuan Formation in the Ordos Basin has various geologicalelements that meet the shale-gas-reservoir-forming standards, and someindicators greatly exceed the standards specified by some experts at home andabroad.

(4) The favorable zones of shale gas in the Taiyuan Formation in the Ordos Basinare primarily located in areas such as the northwestern corner of the TianhuanDepression, the northeastern corner of the Shanbei Slope Belt, and the centraland southern parts of the basin.

(5) The burial depth of the Taiyuan Formation in the Ordos Basin is relativelylarge, making exploration and exploitation only for the shale gas in theformation less feasible; however, developing multiple-layer joint-exploitation


technologies for multiple types of natural gas resources including shale gasand tight sandstone gas could be a significant and realistic goal.

REFERENCESBowker K.A., 2007. Barnett Shale gas production, Fort Worth Basin: Issues and

discussion. AAPG Bulletin 91(4), 523−533.

Carr A.D., Snape C.E., Meredith W., Uguna C., Scotchman I.C. and Davis R.C., 2009.The effect of water pressure on hydrocarbon gene ration reactions: someinferences from laboratory experiments. Petroleum Geoscience 15, 17−26.

Curtis J.B., 2002. Fractured shale-gas system. AAPG Bull 86(11), 1921−1938.

Houseknecht D.W. and Weesner C.M.B., 1997. Rotational reflectance of dispersedvitrinite from the Arkoma Basin. Organic Geochemistry 26, 191−206.

Jin Q., Zha M. and Zhao L., 2001. Identification of Effective Source Rocks in theTertiary Evaporate Facies in the Western Qaidam Basin. Acta SedimentologicaSinica 19(1), 125−129 (in Chinese with English abstract).

Law B.E. and Curtis J.B., 2002. Introduction to unconventional petroleum systems.AAPG Bull 86(11), 1851−1852.

Li Y.X., Nie H.K. and Long P.Y., 2009. Development characteristics of organic-richshale and strategic selection of shale gas exploration area in China. Natural GasIndustry 29(12), 115−118 (in Chinese with English abstract).

Li Z.M., Xu E.S., Qin J.Z., Zheng L.J. and Bao y.j., 2010. Some problems on theevaluation of source rock. Journal of Xi’an Shiyou University (Natural ScienceEdition) 25(6), 8−12 (in Chinese with English abstract).

Liu C.Y., Zhao H.G. and Sun Y.Z., 2009. Tectonic background of Ordos Basin and itscontrolling role for basin evolution and energy mineral deposits. EnergyExploration and Exploitation 27(1), 15−27.

Liu H.L., Wang H.Y., Liu R.H., Zhao Q. and Lin Y.J., 2010. China Shale GasResources and Prospect Potential. Acta Geologica Sinica 84(9), 1374−1377(in Chinese with English abstract).

Mavor M. and Corporation T., 2003. Barnett shale gas-in-place volume includingsorbed and free gas volume. AAPG South-west Section Meeting. Fort Worth,Texas.

McCallister T., 2006. Unconventional Gas Production Projections in the Annualenergy Outlook 2006: An Overview. Washington, D. C: EIA Energy Outlook andModeling Confernece.

Meng Z.Q., Hongguang Ji, Shenjun Qin and Cunliang Zhao., 2012. Organicgeochemical characteristics of source rocks in the Mizhi region of Ordos Basin.Energy Exploration and Exploitation 30(3), 373−388.

Montgomery S.L., Jarvie D.M., Bowker K.A. and Pollastro R.M., 2005. MississippianBarnett Shale, Fort Worth Basin, North-central Texas: Gas-shale play withmultitrillion cubic foot potential. AAPG Bulletin 89 (2), 155−175.

Pollastro R.M., Jarvie D.M., Hill R.J. and Adams C.W., 2007. Geologic framework ofthe Mississippian Barnett Shale, Barnett-Paleozoic total petroleum system, BendArch Fort Worth Basin, Texas. AAPG Bulletin 91(4), 405−436.


Pan R.F., Chen L. and Liu P.C., 2011. Discussion on the method of classifiedevaluation of shale gas resources. Journal of Oil and Gas Technology 33(5),172−174 (in Chinese with English abstract).

Sun Y.Z., Liu C.Y., Lin M.Y., Li Y.H. and Qin P., 2009. Geochemical evidences ofnatural gas migration and releasing in the Ordos Basin, China. EnergyExploration & Exploitation 27(1), 1−13.

Wang Q., Fu X.W., Xu Z.M., Hu S.Z. and Hu X., 2005. Development and applicationof stable carbon iostopes in natural gas and oil geochemistry. NaturalGasGeoscience 16(2), 233−237 (in Chinese with English abstract).

Xu S.L. and Bao S.J., 2009. Preliminary Analysis of Shale Gas Resource Potential andFavorable Areas in Ordos Basin. Natural Gas Geoscience 20(3), 460−465 (inChinese with English abstract).

Zhang J.C., Jin Z.J. and Yuan M.S. 2004. Resrvoiring mechanism of shale gas and itsdistribution. Natural Gas Industry 24(7), 15−18 (in Chinese with Englishabstract).

Zhang J.C., Nie H.K., Xu B., Jiang S.L. and Zhang P.X., 2008. Geological condition ofshale gas accumulation in Sichuan Basin. Natural Gas Industry 28(2), 151−155(in Chinese with English abstract).

Zhao Q., Wang H.Y., Liu R.H., Bai W.H. and Zhang X.W., 2008. Global Developmentand China’s Exploration for Shale Gas. Natural Gas Technology 2(3), 11−14 (inChinese with English abstract).

Reservoir-forming condition analysis and favorable … · ENERGY EXPLORATION & EXPLOITATION·...

Documents

Transcript of Reservoir-forming condition analysis and favorable … · ENERGY EXPLORATION & EXPLOITATION·...