UNITED STATES DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY

Petroleum geology of the Songliao basin, Northeast China

by 

K. Y. Lee

Open-File Report 86-502

This report is preliminary and has not been reviewed for conformity with 

U.S. Geological Survey editorial standards and stratigraphic nomenclature,

1986
CONTENTS

Page

Abstr act - - ----- - i

In troduc t ion 2

Regional setting 3

Purpose, scope, and method of report 3

Strat igraphy 4

Pr e-Jur as s ic 4

Juras sic 4

Cr e tac eous 4

Lower Cretaceous 5

Middle Cretaceous 5

Upper Cretaceous 7

Tertiary 7

Quaternary 8

Structure 8

West Slope 9

North Plunge 9

Central Depression 9

Northeast Uplift 9

Southeast Uplift 10

Southwest Uplift 10

Basin evolution 10

Petroleum deposits 11

Source rocks 12

Reservoirs 14

Po t en t i al 16

Summary and conclusions 16

References cited 18
ILLUSTRATIONS

Page

Figure 1. Index map of China showing the location of study area 2a

2. Geologic map and cross section of the Songliao basin,

Northeast China 3a

3. Structural units and lake shoreline of the first member 

of Qingshankou Formation in the Songliao basin, 

Northeast China 8a

TABLES

Table 1. Orogenic cycles of China 2b

2. Stratigraphy of the Songliao basin, Northeast China 3b

3. Organic geochemical characteristics of the source rocks

in the Songliao basin, Northeast China 12a

4. Evolution of the source rocks in the Songliao basin,

Northeast China i Ja.

5. Depositional environments and physical properties of the 

reservoir sandstone in the Daqing delta complex of the 

Songliao basin, Northeast China 15a

ii
Petroleum geology of the Songliao basin, Northeast China

By K. Y. Lee 

ABSTRACT

The Songliao basin of Northeast China covers about 260,000 km2 with a 

sedimentary rock fill of about 1,560,000 km^. It lies generally within 

lat 42°20' to 49°20' N. and long 120°00' to 128°00' E.

This large basin evolved on a Variscan folded cratonic basement marginal 

to the Da Hinggan Ling* Variscan eugeosyncline foldbelt on the west and 

northwest, the Xiao Hinggan Ling and the Zhangguangcai Ling Variscan eugeosyncline foldbelt on the northeast and southeast, and the Kangping hills of 

the Precambrian Nei Mong shield axis of the Sino-Korean platform on the 

south. It acquired its general form by the continental rifting fragmentation during the Late Triassic Indosinian orogeny. Subsequently, it reached 

full development through the Late Jurassic to Early Cretaceous extensional 

graben development, followed by the Middle Cretaceous basin-wide subsidence and 

syndepositional growth normal faulting during the Yanshanian orogeny (fig. 2). 

The basin acquired further elements of its present configuration during the 

Neogene Himalayan orogeny.

The sedimentary cover of Songliao basin consists chiefly of the the Late 

Jurassic to Neogene fluvial and lacustrine detrital sedimentary rocks. Triassic and Early Jurassic strata are generally missing throughout the basin. 

The cratonic basement consists of undifferentiated platform metamorphic and 

sedimentary rocks of Precambrian to Permian ages. The Late Jurassic strata 

are represented by 500 to 1,300 m of a coal-bearing series, which is generally 

thicker in the east and southeast parts of the basin. As shown in detailed 

studies, the Cretaceous strata are widespread throughout the basin. During 

the sedimentation of the Middle Cretaceous sedimentary rocks, two high-waterlake stages, covering areas from 87,000 to 200,000 km2 , are recorded in the 

first members of the Qingshankou and the Nenjiang Formations, respectively. 

As the lake water regressed during Qingshankou and Yaojia times, the Daqing 

delta system formed on a gently southward-dipping paleoslope.

Principal structural units in the present-day Songliao basin are the 

West Slope, North Plunge, Central Depression, Northeast Uplift, Southeast 

Uplift, and Southwest Uplift (fig. 3). Current petroleum producing areas 

are concentrated in the Central Depression and the Southeast Uplift.

Potential petroliferous source rocks in the Songliao basin are shale, 

oil shale, and mudstone of the Qingshankou, Nenjiang, Yaojia, Quantou, and 

Denloukou Formations of Cretaceous age, as well as the Upper Jurassic shale 

of the coal-bearing series. Of these, the most favorable source rocks are 

confined to the first members of the Qingshankou and Nenjiang Formations. 

Three major kerogen types, I, II, and III, are defined. Type I is sapropelic

* Mountain range
and consists chiefly of lipids. Type III is typically humic and consists 

chiefly of vitrinite derived from higher terrestrial plants. Type II, a 

mixed type, ranks chemically between the sapropelic type I and the humic 

type III. It is subdivided into type IIA and IIB. Type HA is rich in 

lipids; however type IIB is rich in aromatic matter. Type I matured successively earlier than types II and III (Yang and others, 1985, p. 1114, fig. 5, 

p. 1119, and 1121).

Four stages of oil and gas generation are defined by Yang, Li, and Gao 

(1985, p. 1119-1120). Burial depth of the mature to highly mature stages 

ranges from 1,300 to 2,900 m. Both the formation temperature and the heat 

flow are high. The mean geothermal gradient of the main producing area is 

4.2°C/100 m. The average earth heat flow is 1.70 x 10~6 cal/cm2 /sec. The 

source rock and crude oil correlation is shown by the ^ Q value of stable 

carbon isotopes.

Reservoir rocks of the principal producing pay zones consist chiefly of 

delta front fine-grained sandstone. In descending order, the reservoirs of 

the Songliao basin are grouped into the upper Heidimaio, the middle Shaertu, 

Putaohua, and Gaotaizi, and the lower Fuyu, Yangdachengzi, and Nongan. The 

prominent producing pay zones are confined in the Shaertu, Putaohua, and 

Gaotaizi reservoirs of the Daqing delta complex in which an expected reserve 

is about 5 billion barrels of oil. Of these three, the Putaohua contains 

about 70 percent of the total, 3.5 billion barrels of oil. It is made up 

chiefly of the first member of the Yaojia Formation in the Daqing delta depositional system, which, tentatively, is correlated with Ma's Xingshugang 

delta (Ma, 1985).

The Daqing oil field of the Central Depression is a supergiant field. 

Oil and gas in the reservoirs are trapped by anticlinal and nose-shaped 

folds, fault barriers, and lithofacies changes, which are then sealed by 

overlying shale and mudstone. Simultaneous oil and gas maturation, migration 

along carrier beds, and structural trap formation were responsible for the 

formation of the giant Daqing oil field from the Late Mingshui to Late Yian 

time.

Petroleum potential of Songliao basin is substantial. International 

Encyclopedia (1985) lists the original oil in-place of Daqing oil field as 

about 21.9 billion barrels. Future new discoveries are favorable in the 

delta front sandstone of the Quantou and Denlouku Formations in the southern 

part of the basin.

INTRODUCTION

Songliao basin of Northeast China is a rhombic-shaped depression running 

northeasterly across the central portions of both Heilongjiang and Jilin 

provinces and the northern part of Liaoning province (fig. 1). Initially it 

evolved from extensional stresses on a Variscan folded cratonic basement 

during the latest episode of the Indosinian orogeny in Late Triassic time 

(table 1) (Ma, Liu, and Su, 1984; Huang, 1984). The cratonic basement of
XT 90» yr 100* 120* 130*

so*

40*

30*

) \ <c"\

' V_x-y" x \ \_

> -( ^-7

/ /^ Hei£pj«ng (Hei) 

^ 'vr ^N __( \ ^? I - --A < 

S

^1 Xinjiang(Xin)

Sichuan (Chuan or Shu) 

«f

Province with one choroder alternative name 

in parenthesis.

 - - - International boundary

 - Internal administrative boundary

0 100 201 300 400 SOOMIES

0 700 400 eOOKIOMETERS

SOUTH CHINA SEA

HMHM1

100* HO* J20*

Figure I. Index mop of Chino showing the location of study area.
Table 1. Orogenic cycles of China (After Hoang and others, 1980, table 4, p. 106),

Geologic

Cenozoic

Mesozoic

Paleozoic

Pro-terozoic

Archean

Chronology

Quaternary

Tertiary

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Sinian

Qingbaikou

Jixian

Nankou

Changcheng 

Hutuo

Wutai

Fuping

Isotopic

*g«

(m.y. )

1.5 -

67

137

190

230-

280

350

A05

440

550

570

770

1100

1400

1700

1950

2500

H2

Hi

^3

*2

YT

1

V4

V3 

V7

v l

C2

Cl

Orogenic cycles

Himalayan (H)

Yanshanian (Yenshanian) (Y)

Indosinian (I)

'

Variscan (V)

-.-

Caledonian (C)

Xingkailan (Hsingkaiian)

Yangriian (Yangtzeian)

7

Wulingian

Zhongtiaoian (Chungtiaoian)

Wutaiian

Fupingian
the basin borders the Da Hinggan Ling* Variscan eugeosyncline foldbelt on 

the northwest and west, the Xiao Hinggan Ling and the Zhangguangcai Ling 

Variscan eugeosyncline foldbelt on the northeast and the southeast; on the 

south it is in contact with the Kangping hills of the Precambrian Nei Mong 

shield axis of the Sino-Korean platform (fig. 2)(Huang and others, 1980, 

fig. 18-b, p. 29-33). The basin reached full development through extensional 

graben development and syndepositional growth faulting from Late Jurassic to 

Middle Cretaceous time during the Yanshanian orogeny. It acquired its present 

configuration during the latest episode of the Late Cretaceous Yanshanian 

and the movements of the Neogene Himalayan extensional orogenies (table 1).

The basin filled with Late Jurassic coal-bearing sedimentary sequences 

and with Cretaceous to Quaternary fluvial and lacustrine detrital sediments 

derived from the adjacent highlands (fig. 2). Petroleum resources are substantial, and output of the basin ranks first in China. The petroleum source 

rocks are mudstone and shale, chiefly of Early to Middle Cretaceous age. 

The reservoir rocks are mostly the fluvial channel and delta-front finegrained sandstones of Middle Cretaceous age. Information on coal resources 

of the Songliao is not available, but generally coal beds in the basin are 

too deeply buried for the reserve consideration.

Regional Setting

Songliao basin occupies an area about 260,000 krar and contains a volume 

of sedimentary rock amounting to about 1,560,000 km , it is confined within 

lat 42°20' to 49°20' N. and long 120°00' to 128°00' E. It is bounded on the 

northwest by the Da Hinggan Ling, on the northeast by the Xiao Hinggan Ling, 

on the southeast by the Zhangguangcai Ling, and on the south by the Kangping 

Hills (fig. 2). The Songliao was one of the largest lake basins in the 

Asian continent in Cretaceous time. From Triassic to Middle Jurassic, the 

basin was an emergent landmass, and, subsequently, because of the Yanshanian 

movement, it subsided receiving coal-bearing detrital sediments in Late 

Jurassic time. The Late Jurassic and Cretaceous sedimentary cover reaches a 

maximum thickness of more than 8,000 m (table 2), overlying the pre-Mesozoic 

metamorphosed crystalline platform basement. Extensive systematic petroleum 

exploration began in the late 1950*s, and a concentrated development program 

began in the late 1960's (Meyerhoff, 1982, p. 244-250).

Purpose, Scope, and Method of the Report

The primary purpose of this report is to provide a synthesis of selected 

current literature on petroleum geology of Songliao basin in order to understand geologic factors relating to a resource assessment. The Pinyin system 

from the Gazetteer of the People's Republic of China (Defense Mapping Agency, 

1979) is used for Chinese name transliteration, and the Chinese Dictionary 

is used for geographic names not listed in the Gazetteer.

* Mountain range
STRATIGRAPHY

Based on information from surface and subsurface investigations and 

geophysical surveys, the stratigraphy of the basin is divided, in ascending 

order, into the pre-Jurassic, Jurassic, Cretaceous, Tertiary, and Quaternary 

sedimentary sequences (table 2) (fig. 2). The Triassic and Lower to Middle 

Jurassic strata are reported to be missing. Although Chen Chin (1980) stated 

the presence of the Middle Jurassic strata, Yang and others (1983) and Wang 

and others (1983, p. 237-240) do not recognize the presence of Middle Jurassic 

beds in the basin. The most prolific petroleum source beds are found in the 

Cretaceous sequences, as discussed in detail below.

Pre-Jurassic

The stratigraphy of the pre-Jurassic strata consists of undifferentiated 

platform metamorphic and sedimentary rock complexes ranging in age from Precambrian to Permian. The rock assemblages of the pre-Jurassic basement in 

the basin consist chiefly of Precambrian gneissic granite, quartzite, schist, 

marble, and amphibolite; of Silurian and Devonian quartzose sandstone, crystalline limestone, hornfels, slate, phyllite, conglomerate, and tuff interbedded 

with pyroclastic rocks; and of Carboniferous to Permian crystalline limestone, 

quartzite, slate, shale, breccia, and hornfels intruded by biotite and biotitehornblende granites (Institute of Geology, Academia Sinica, 1958, p. 123-124).

Jurassic

The Jurassic system of Songliao basin is represented by Upper Jurassic 

continental coal-bearing sedimentary sequences and is concentrated in the 

Grabens throughout the basin (fig. 2). In the lower part, the rock assemblages consist of light-gray to gray coarse-grained and feldspathic sandstone, 

conglomeratic sandstone, shale, and mineable coal beds with basal tuff, 

andesite, and conglomerate; and in the upper part, of light-brown sandstone, 

quartzite, mineable coal, and andesite. The unit is about 550 m thick but 

is as much as 1,300 m thick in the eastern part of the basin (Wang and Liu, 

1980, p. 252-254; Intitute of Geology, Academia Sinica, 1958, p. 121-124; 

Liu, 1983).

Cretaceous

The Cretaceous system has been studied in detail during the past decades. 

This system is widely distributed throughout the basin, and in the central part 

of the basin, it consists of more than 6,000 m of fluvial and lacustrine 

detrital sediments derived from the adjacent highlands. In this report, the 

system is divided, in ascending order, into the Lower, Middle, and Upper 

Series (table 2) (Ma, Yang, Ding, and Guan, 1984; Wang and Liu, 1980, table 

16-11, p. 276; Gu, 1982; Chen and others, 1982). Wang and Liu (1980) propose 

that the Songhua Jiang Group represents the Middle and Upper Series. This 

discussion on the Cretaceous stratigraphy emphasizes depositional environments 

and lithofacies distribution relative to the subsequent discussion on petroleum 

migration and accumulation (table 2).
Lower Cretaceous

The Lower Cretaceous strata of the Songliao basin lie unconforaably on 

the Upper Jurassic volcanic series in the grabens as well as on the basement, 

and are represented by the Denlouku Formation. In ascending order, the 

Denlouku Formation is divided into four members. The first member consists of 

119 to 220 m of grayish-green sandstone and mudstone with basal conglomeratic 

sandstone. The second member is composed of 309 to 700 m of grayish-green 

and black mudstone, shale, and tuffaceous sandstone. The third member consists of 250 to 621 m of grayish-green and gray mudstone and sandstone interbeds. The fourth is made up of 134 to 212 m of grayish-green and dark-gray, 

tuffaceous sandstone and mudstone interbeds (table 2). During sedimentation 

of the Denlouku Formation, the central part of the basin was a northeasttrending landmass, and the eastern and western flanks of this landmass bordered 

graben-faulted troughs. The first and second members of the Denlouku were 

deposited within the troughs, but the third and fourth members later partially 

overlapped the top of the landmass (Wang and others, 1983, p. 237-240). The 

thickest Denlouku sedimentary beds of 1,700 m are recorded in the western 

trough, which is located about 50 km northwest of the city of Anda in the 

south-central part of Heilongjiang province. Generally, Wang and Liu (1980, 

p. 274) consider that the Denlouku lake sediments cover only small areas.

Middle Cretaceous

The Middle Cretaceous strata lie conformably on the Lower Cretaceous sedimentary rocks. In ascending order, the Middle Cretaceous is represented by the 

Quantou, Qingshankou, Yaojia, and Nenjiang Formations, which contain the most 

prolific source and reservoir rocks in the Songliao basin (table 2). During 

high-water times, the lake water coverage ranged from 87,000 to 200,000 km^ 

(Wang and others, 1983, table 2-4-22, p. 113).

The Quantou Formation is divided, in ascending order, into the first, 

second, third, and fourth members (Chen, 1980; Ma and others, 1984) (table 2). 

The first member consists of 356 to 651 m of light-gray and grayish-green 

fine- to medium-grained, feldspathic sandstone with basal conglomeratic sandstone, grading upward into reddish-blue to red silty mudstone, which laterally 

changes into coarse-grained and conglomeratic sandstone toward the basin border. 

The second member is made up of 212 to 417 m of mudstone and shale interbeds, 

locally intercalated with black mudstone, gray siltstone, and sandstone. 

The volume of the sandstone increases near the basin rim. The third member 

is composed of 451 to 672 m of gray sandstone and siltstone and variegated 

mudstone, which grades upward into grayish-green and black mudstone. The 

fourth member consists of 65 to 98 m of reddish-brown sandstone intercalated 

with mudstone, shale, and oil shale. Fossil fauna of the Quantou Formation 

consist of ostracods, fossil fish, and plants. During the Quantou time, the 

lake-water coverage greatly expanded, accompanied by large scale graben-faulting 

throughout the basin. The third and fourth members extensively overlapped 

older sedimentary sequences (Wang and others, 1983, p. 240).

The Qingshankou Formation is divided, in ascending order, into three 

members (table 2) (Chen, 1980; Ma, Yang, Ping, and Guan, 1984). The second 

and third members are combined in the lithologic description. The first
member of the Qingshankou is characterized by 72 to 131 m of black mudstone 

and shale with basal oil shale (fig. 3). Banded siderite and pyrite grains 

are present. This member grades upward into siltstone in the uppermost part 

of the sequence. This member is mainly represented by lacustrine deposits 

of fine clastic sediments with some sandstone interbeds near the basin border. 

Ostracods are abundant. The second and third members are composed of 273 to 

503 m of black, gray, and green shale, limestone, siltstone, and mudstone 

in the central part of the basin, grading laterally toward the northwest 

into alternate sandstone, conglomeratic sandstone, and mudstone near the 

basin border. Ostracods and conchostracans are rich. During Qingshankou 

time, the lake became fully developed and was accompanied by subsidence of 

the Central Uplift landmass. Sedimentation of the Qingshankou sequences 

generally reached a rate of deposition greater than that of sediment influxes, 

as characterized by the predominance of lacustrine, mudstone, shale, and 

fluvial deltaic sandstone.

The Yaojia Formation is divided, in ascending order, into three members 

(table 2) (Ma, Yang, Ding, and Guan, 1984). The second and third members are 

combined in the lithologic description. The first member of the Yaojia 

consists of interbeds of gray to grayish-green siltstone and sandstone and 

dark-purple to reddish-green mudstone, which range from 0 to 78 m thick. 

This unit grades upward into the second member of the formation. The second 

and third members are characterized by 72 to 150 m of grayish-green and reddish-green shale and mudstone, which laterally change into gray, feldspathic 

sandstone, siltstone, and mudstone with some conglomerate near the basin 

border (table 2). According to Wang and others (1983, p. 240), the Yaojia 

second and third members were deposited in a deep lake to fluvial deltaic 

environment, which continued through most of the time span of the overlying 

Nenjiang Formation. Fossil fauna consist chiefly of pelecypods, gastropods, 

ostracods, and charophytes, in which ostracods are sporadic in this formation.

The Nenjiang Formation is the most extensively distributed formation in 

the Songliao basin. It is also called the "Fulongquan Formation" by Chen Chin 

(1980, p. 239, fig. 4). Chen gave the Nenjiang age as Early Late Cretaceous 

as well as Late Early Cretaceous. However, in this report, the author prefers 

the classification and correlation by Wang and Liu (1980, p. 276, table 16-11) 

and designates a Late Middle Cretaceous age for the Nenjiang (table 2).

In ascending order, the Nenjiang Formation is divided into five members 

(table 2) (Ma, Yang, Ding, and Guan, 1984; Chen, 1980). The first three 

members are characterized by the presence of lucastrine to deltaic and fluvial 

lithofacies, whereas the second two members are indicated by well sorted fineto medium-grained fluvial sandstone and the absence of distinct deltaic lithofacies. The first member consists of 27 to 222 m of light-gray to grayish-black 

mudstone, shale, and oil shale, locally interbedded with light-gray siltstone 

to fine-grained sandstone. The oil shale generally is located in the basal 

part of the unit and is very rich in fossil fauna. Calcareous concretions are 

abundant in the shale and mudstone. The second member is made up of 170 to 

251 m of gray and black shale, oil shale, and mudstone, grading upward into 

black mudstone interbedded with siltstone, which laterally changes into siltstone. Chen Chin (1980) stated that conchostracans are concentrated along 

bedding planes of oil shale. Other fauna include pelecypods, gastropods,
ostracods, and fragments of fish and plants. The third member comprises 70 

to 131 m of gray to black mudstone and shale intercalated with thin-bedded 

reef-limestone, bioclastic limestone, and marl. This sedimentary sequence 

grades upward and laterally through salty mudstone and argillaceous siltstone 

into fine- and medium-grained sandstone near the basin border. Ostracods, 

gastropods, and pelecypods are common. The fourth member consists of 234 to 

304 m of grayish-green shale, mudstone, siltstone, and sandstone in alternate 

sequences, in which thin-bedded calcareous sandstone is in the lower part 

and dark purplish-red mudstone is in the upper part (Chen, 1980, p. 241). 

Fossil fauna are ostracods, brachiopods, and pelecypods. The fifth member 

is made up of 0 to 355 m of grayish-green dark-purple and red massive mudstone 

shale and siltstone intercalated with grayish-green fine- to medium-grained 

sandstone. Fossil fauna are scarce.

Upper Cretaceous

The Upper Cretaceous strata lie unconformably on the Middle Cretaceous 

sedimentary rocks and are represented, in ascending order, by the Sifangtai 

and Mingshui Formations, which were deposited in a waning lake stage (table 2).

The Sifangtai Formation is widely distributed in the Songliao basin and 

consists of 0 to 394 m of alternate grayish-green, red mudstone, siltstone, 

and some sandstone. Calcareous conglomerate beds are near the base containing 

mollusks and ostracods.

The Mingshui Formation is divided, in ascending order, into two members. 

The first member consists of 0 to 243 m of alternate black, dark purplish-red 

and grayish-green mudstone, shale, and sandstone, which locally contain the 

basaltic flow near the base. This member is characterized by the presence 

of black shale beds in the upper and middle parts with a thin pyrite layer 

at the base (Chen, 1980, p. 241). Ostracods, conchostracans, gastropods, 

and pelecypods are present. The second member is composed of 0 to 354 m of 

orange-red to variegated mudstone intercalated with conglomerate. Gastropods 

and pelecypods are common in association with scattered ostracods, plants, 

and charophytes (Chen, 1980, p. 242).

Tertiary

The Tertiary system of Songliao basin consists of continental deposits 

of detrital sediments derived from the adjacent highlands. In ascending order, 

this system is divided into the Paleogene and Neogene series. At present, 

a detailed study of Tertiary stratigraphy is not available. The Paleogene 

unconformably overlies the Cretaceous and is represented by the Yian Formation. 

The Neogene of the basin is represented, in ascending order, by the Daan and 

Taikang Formations (table 2).

The Yian Formation consists of 0 to 221 m of light-brown coarse-grained 

sandstone and basal conglomeratic sandstone grading upward through grayishgreen and black mudstone and shale with lignite beds into black, grayish-green 

mudstone and siltstone, and, locally, with tuffaceous and andesitic volcanic 

flows and pyroclastic rocks.
The Daan Formation unconformably overlies the Yian Formation (table 2), 

but, locally, conformably (Chen, 1980, p. 242). It comprises 0 to 93 m of 

light-gray to gray conglomeratic sandstone and sandstone grading upward into 

gray mudstone and siltstone. Chen Chin (1980, p. 242) mentions that this 

formation unconformably overlies the Cretaceous in the western and southern 

parts of the basin. Fossils are scarce. The Taikang Formation is in contact 

conformably with the Daan and consists of 0 to 122 m of light-gray, loose 

basal conglomerate and sandstone grading upward into siltstone and mudstone. 

Fossils are made up of plant remains and ostracods.

Quaternary

The Quaternary system of Songliao basin is undifferentiated and consists 

of 40 to 133 m of glacial outwash sand and gravel and fluvial red, greenishgray clay intercalated with calcareous concretions, grading upward into silt 

and light-yellow clayey sand and gravel. This sequence is probably disconformably covered by alluvial clay, silt, and channel sand and gravel, and, 

locally, by peat beds.

STRUCTURE

The Songliao basin was a stable structural block in the Precambrian time 

(Wang and Qiao, 1984; Li and Xue, 1983). Subsequently, the Songliao was 

covered by Paleozoic platform sedimentary rocks and evolved by accretion into 

an integral part of the Neimeng-Da Hinggan Ling and the Xiao Hinggan LingZhangguangcai Ling Variscan fold systems (Huang and others, 1980) (figs. 2 

and 3). In the Songliao basin, the Variscan fold systems of the basement 

entailed three anticlinoriums and two synclinoriums trending N. 25°-40° E. 

(Yang, 1983, p. 187). The basin was uplifted with granite intrusion during 

the late episode of the Variscan orogeny (table 2). The initial depositional 

framework of the Songliao was formed by north-northeasterly-trending extensional 

fault systems during the late episode of the Indosinian orogeny in the Late 

Triassic. During the Late Jurassic and Early Cretaceous Yanshanian orogeny, 

the basin reached its full development stage with the formation of three 

northeastern deep fault systems, which consist of the Nenjiang-Baicheng deep 

fault zone along the west basin border, the Yilan-Yitong deep fault zone 

along the east basin border, and the Sunwu-Shuangliao in the central part 

of the basin (fig. 2) (Yang, 1983, p. 188). These fault systems controlled 

the development of the basin-fills during the lacustrine sedimentation of 

the Qingshankou, Yaojia, and Nenjiang Formations in the Middle Cretaceous 

(Yang, 1985; Wang and others, 1983; Ma and others, 1982). Subsequently, the 

basin acquired its present configuration with various types of anticlinal 

and synclinal folds and normal and strike-slip faults during a late phase of 

the Yanshanian orogeny from the Mingshui to the Yian (Yang, 1985) (table 2).

The structure of the basin is classified into six major structural units, 

based on structural patterns, areal distribution, development status within the 

basin, variation in thicknesses of sedimentary beds, and surface-structural 

characteristics of the sedimentary cover (fig. 3) (Wang and others, 1983, p. 241; 

Ma, Liu, and Su, 1984). These six units are the West Slope, North Plunge, Central 

Depression, Northeast Uplift, Southeast Uplift, and Southwest Uplift, of which 

subunits are given for five of those six structural units but details are not 

available.

8
I. West Slope.

II. North Plunge* 

II ,Nenjlong step;

ll2lYiansag;

II ,Sanxing

anticline; 

IL, Keshan-Yitong

anticline;

II Qionyuan structure 

5

II Wuyursag. 

6,

VI. Southwest Uplift: 

VI Jiomatu rise;

and 

VI t Kailu sag.

Boundaries of structural 

units.

III. 

X

Central Depression:

, Heiyupoo sag; 

III ,Mlngshui step;

I" ,Longhupoo-Doan step;

o 

III ,Qijio-Gulong sag;

4

III ,Doqing central basin

5 high;

Ml , Sonzhoo sag; 

. o

IH-fChooyanggou step;

III ,Chongling sag;

8 and

IN ,Fuyu-Huazijing step

9

IV. Northeast Uplift 

IV Hailun rise; 

IV2 ,Suilun

antidine; 

IV .Suihua sag;

IV ,0ingan rise; 

^ and

IV ,Hu lon rise. 

5

V. Southeast Uplift:

V. ,Changchunling

anticline; 

V ,Wangfu sag of

2 Bin Xian; 

V,, Oingshonkou rise;

V f Denlouku 

4 qnticline;

V ,Diaoyutoi rise;

V ,YangdochengzS

6 anticline 

V ,Yushu-Dehui sag;

7 and

V Jiutai step.

8

Lake shoreline of the first member of Boundary of basin, 

the Oingshonkou Formation.

0 100 200 Miles

100 200 300 Kilometers

Rgure 3. Structural units .and lake shoreline of the first member of Qlngshgnkou Format ion in the 

Songlioo basin,Northeast China(modified after Wangondothefs,l983;Rgune4-9-4,p.242> 

and Yang and others,1985; Figure 3,p. 1116).

8a
West Slope

The West Slope is situated in the western part of Songliao basin. According 

to Wang and others (1983, p. 241), the basement in this area has a flat surface 

with small-scale graben structures. The burial depth of the basement ranges 

from 500 to 2,000 m. The sedimentary rock cover was folded into a regional 

large-scale monocline which gently dipped basinward to the area of the Central 

Depression. The monocline contains numerous small-scale, nose-shaped structures. 

The second and third members of the Quantou Formation overlap old strata 

toward the basin border (fig. 3). Throughout this area, facies changes and 

stratigraphic pinch-outs are generally common.

North Plunge

The North Plunge is herein named after the crystalline basement of the 

area, which plunges southward. The unit consists of six subunits. They are 

the Nenjiang step, Yian sag, Sanxing anticline, Keshan-Yilong anticline, 

Qianyuan structure, and the Wuyur sag (fig. 3). The burial depth of the 

basement ranges from 300 to 3,000 m (Wang and others, 1983, p. 241-242). The 

sedimentary cover was folded mostly into the nose-shaped structures. In this 

area, northeast and east-west fault systems are commonly present, and the 

Quantou sedimentary strata overlap the older beds toward the north (Wang and 

others, 1983, p. 242).

Central Depression

The Central Depression contains the Daqing oil field of Songliao basin 

and covers about 29,000 km2 (fig. 3) (Wang and others, 1983, p. 241; Yang 

1985). This unit is made up of the following nine subunits, the Heiyupao sag, 

Mingshui step, Longhupao-Daan step, Qijia-Gulong sag, Daqing central basin 

high, Sanzhao sag, Chaoyanggou step, Changling sag, and Fuyu-Huazijing step 

(fig. 3). Of these subunits, the Daqing central basin high is located in 

the central part of the Central Depression. Yang Wanli (1985, p. 1101-1102) 

stated that from the Late Cretaceous Mingshui to the Late Paleogene Yian time, 

the Daqing central basin high was intensely folded and faulted; this subunit 

comprises seven principal anticlines separated by saddles and broken by about 

600 northwesterly striking normal faults; and closures of these anticlines range 

generally from 775 to 900 m in an area of 2,800 km2 . Generally, the basement 

of this depression has a burial depth ranging from 4,000 to 7,000 m, locally 

reaching 9,000 m, and has been cut and broken chiefly by graben faults (Ma, Liu, 

and Su, 1984, fig. 2, p. 612; Wang and others, 1983, p. 241). Geophysical 

data show that in the central part of the unit the earth's crust is relatively 

thin with a high heat-flow value (HFU) (figs. 2 and 3) (Ma, Liu, and Su, 1984, 

fig. 7, p. 616 and fig. 9, p. 618). The Cretaceous sedimentary sequences are 

complete in succession and were folded into an anticlinal structure, which was 

truncated by numerous northwestern normal faults (Yang, 1985, p. 1102-1103).

Northeast Uplift

The Northeast Uplift began to form at the end of the Mingshui Formation 

and consists of the Hailun rise, Suilun anticline, Suihua sag, Qingan rise, 

and Hulan rise (fig. 3). The sedimentary cover is more than 3,000 m thick.
A complete stratigraphic sequence is located in the Suihua sag (Wang and 

others, 1983, p. 241).

Southeast Uplift

The Southeast Uplift formed during the latest episode of the Yanshanian 

orogeny in Late Cretaceous; subsequently, eight subunits developed throughout 

the area. These are the Changchunling anticline, Wangfu sag of Bin Xian, 

Qingshankou rise, Denlouku anticline, Diaoyutai rise, Yangdachengzi anticline, 

Yushu-Dehui sag, and Jiutai step (fig. 3). Wang and others (1983, p. 241) 

reported that the Lower to Middle Cretaceous strata are 3,500 m thick in the 

Wangfu sag of Bin Xian and the Yushu-Dehui sag.

Southwest Uplift

The Southwest Uplift is a graben-faulted block of Late Jurassic age and 

consists of the Jiamatu rise and the Kailu sag (fig. 3). In this area, the 

Yaojia and Nenjiang Formations are extensively distributed. Most of the area 

is untested (Wang and others, 1983, p. 243).

BASIN EVOLUTION

As mentioned before, the presence of three northeast-trending deep fault 

systems in Songliao basin controlled the subsequent development of the major 

structural units as well as the sedimentary fill of the basin. From Late 

Jurassic to Late Cretaceous, the basin underwent three principal stages of 

development: intense extensional rifting with graben faulting from Late 

Jurassic to Early Cretaceous; in the Middle Cretaceous, basin-wide subsidence 

due to further extensional basin fragmentation; and a final basin waning 

stage due to uplifting of the central, northeastern, and southeastern parts 

of the basin during the latest episode of the Yanshanian orogeny from the 

Mingshui to the Yian (Ma and others, 1982; Ma, Liu, and Su, 1984; Yang, 

1985; Ma, 1985).

Since its initial extensional rifting in Late Triassic to Early Jurassic, 

Songliao basin underwent fragmentation and expansion associated with extensive 

igneous activity. During the early episode of the Yanshanian orogeny in Late 

Jurassic to Early Cretaceous time, the basin became intensely rift- and grabenfaulted with wide emplacement of intermediate and acidic magma, creating a 

central uplift belt separating the basin into two northeast-trending faulted 

sags, one in the east and the other in the west (Ma and others, 1982, p. 293). 

Both sags were filled with Jurassic fluvial and marsh deposits of detrital 

sediments with thick coal beds and volcanic rocks and Early Cretaceous purplishred mudstone, shale, and coarse detrital sandstone and conglomeratic sandstone. 

Total thickness of the Late Jurassic and Early Cretaceous sequences reached 

a maximum of about 3,000 m (table 2).

In the Middle Cretaceous, the areal coverage of Songliao basin expanded 

to more than 200,000 km2 (Wang and others, 1983, p. 240). Especially at 

the time of deposition of the Qingshankou, Yaojia, and Nenjiang Formations, 

the central uplift belt subsided, in association with the growth of the pre10
ceding rift- and graben-faults in the basin, to form the Central Depression 

with the merging of its eastern and western faulted sags (Ma and others, 

1982, p. 293). During that time the Songliao lake formed with a bottom 

surface which was gently sloping down toward the depocenters (fig. 2). 

Generally, the basin subsidence rate was over over 0.1 mm per year, as given 

by Ma and others (1982), and an average area of the deeper lake facies was 

estimated to be 50,000 km2 with deposits of 500 to 800 m of dark mudstone.

During the sedimentation of the Qingshankou and Yaojia Formations, three 

large deltaic deposits developed in the northern, western, and southwestern 

parts of the lake basin (Ma and others, 1982). Delatic deposits are not 

reported in the eastern part of the basin, however. Of these three deltas, 

the northern delta, located in the northern part of the Central Depression, is 

the most prolific for petroleum production. This delta is also called the 

"Daqing delta" by Chungyu Wu (1982). The author believes that the Daqing 

delta includes Ma's Xingshugang delta formed in Early Yaojia time, which is 

equivalent to the Yaojia-1 lobe shown as below, and Heiyupao delta (Wang and 

others, 1983, fig. 4-9-3, p. 239) formed in Late Qingshankou time. Wu (1982, 

p. 12) considered that the Daqing delta developed during a period of lake 

regression, which occurred between two major lake transgressive events, as 

indicated by the first members of the Qingshankou and Nenjiang Formations, 

respectively (table 2) (fig. 3). The Daqing delta consists of detrital 

sediments derived from the highlands to the north. It extends from the swamp 

and marsh of the Heiyupao sag southward to the site of Putaohua and continues 

to project into the center of the basin (Ma, 1985; Wu, 1982, p. 12). The 

delta covers an area about 20,000 to 44,000 km2 and consists of more than 

200 lobes of elongate tongue-like and bird-foot shapes with a total thickness 

of 500 to 600 m (Wu, 1982, p. 12; Ma and others, 1982, p. 299). The longest 

lobe, Yaojia-1, is about 200 km and indicates that, during the sedimentation 

of Yaojia Formation, the paleoslope of depositional framework was gentle, 

less than 0.5 m per km along the fluvial plain, less than 0.1 m per km on 

the deltaic plain, and about 0.8 m per km along the delta front (Wu, 1982, 

p. 12). Development of the Daqing delta depositional system is the most 

important geologic factor, accounting for about 70 percent of the total 

reserves of petroleum deposits in Songliao basin. During early Nenjiang 

time, the lake basin reached full development with overlapping deposition 

in the western, northern, and northeastern parts of the basin (Ma and others, 

1982, p. 293).

In Late Cretaceous, the Songliao lake gradually reached its waning development stage. From the Late Cretaceous Mingshui to the Late Paleogene Yian 

time, the tectonic activities in the basin reached a culminating stage (Yang, 

1985, p. 1101) (table 2). Generally, the Late Cretaceous strata are missing 

in the northeastern and southeastern parts of the basin because of regional 

uplift in the east half. The center of subsidence shifted westward, and 

throughout the basin, the alluvial and fluvial deposits dominated (Ma and 

others, 1982, p. 293).

PETROLEUM DEPOSITS

The petroleum deposits of Songliao basin have been well documented 

during the past several years (Masters and others, 1980; Xu and Wang, 1981;

11
Meyerhoff, 1982; Ma and others, 1982; Wang and others, 1983, p. 237-243; Ma 

Yang, Ding, and Guan, 1984; Yang, 1985; Yang and others, 1985; Ma, 1985). 

Since 1959, with the discovery of three commercial oil and gas wells in the 

Central Depression, the so-called "Daqing oil field" of Songliao basin has 

developed into one of the giant oil and gas fields of the world. In this report, discussion will emphasize the geologic factors controlling the formation 

of oil and gas resources of nonmarine origin. Most of the producing fields 

are concentrated in the Central Depression of the basin (figs. 2 and 3).

Source Rocks

The potential sources rocks in Songliao basin are the Late Jurassic 

coal-bearing series and the Cretaceous shale, mudstone, and oil shale. 

Detailed investigations by Chinese petroleum geologists indicate that the 

organic matter-rich Middle Cretaceous fine detrital sediments are solely 

responsible for the generation of almost all oil and gas deposits in the basin. 

The Middle Cretaceous source rocks are concentrated, in ascending order, in 

the Qingshankou, Yaojia, and Nenjiang Formations. The most favorable source 

rocks are the eutrophic fresh to brackish water lake deposits of the black 

mudstone, shale, and oil shale of the first member of the Qingshankou and 

Nenjiang Formations. Generally, favorable source rocks are the black, gray 

and green shale and mudstone of the second and third members of Qingshankou 

Formation. The less favorable source rocks are the lake marsh and swamp 

deposits of grayish-green and reddish-green shale and mudstone of the second 

and third members of the Yaojia Formation, as well as the mudstone and shale 

of the Quantou Formation (tables 2 and 3) (Yang and others, 1985, table 1 and 

fig. 1, p. 1113). On the basis of organic geochemical characeristics of 

source rocks, Yan, Li, and Gao (1985) classified and defined the kerogen in 

Songliao basin into three major types: I, II, and III, of which type II is 

subdivided into subtypes IIA and IIB (table 3).

The type I kerogen is sapropelic and consists chiefly of lipids derived 

from lake-dwelling organisms and higher terrestrial plants (Yang and others, 

1985, p. 1112-1121). The H/C atomic ratio of the kerogen is larger than 1.4, 

and the 0/C ratio is less than 0.1 (table 3). The hydrogen index derived 

from the source rock by pyrolysis is larger than 650, and the oxygen index 

is less than 25 (Yang and others, 1985, table 2, p. 1114). The characteristics 

of n-alkane and isoprenoid are shown in table 3. Yang, Li, and Gao (1985, 

p. 1112) further state that by pyrolysis at 450°C, the amount of hydrocarbon 

produced from the kerogen is more than 42 percent. Generally, type I has a 

small number of free radicals and a high potential for the genesis of petroleum.

The type II kerogen of the basin chemically ranks between the sapropelic 

type I and the humic type III. Type II generates a less amount of hydrocarbon 

as compared with type I and is a mixed type derived from a mixture of two 

different precursors: the lipid-rich lake-living organisms and the aromatic-rich 

higher plants (Yang and others, 1985, p. 1114). On the basis of elemental 

analysis and pyrolysis hydrogen and oxygen indices (Yang and others, 1985, 

table 2, p. 1114), type II is subdivided into type IIA and type IIB (table 3). 

Type IIA is rich in lipids of which the liptinite content ranges from 50 to 

90 percent. Yang and others (1985, p. 1114) show in table 2 that type IIA 

kerogen has an H/C atomic ratio of 1.0-1.4, an 0/C ratio of 0.10-0.15, and 

hydrogen and oxygen indices of 450-650 and 25-50, respectively. Type IIB is

12
Table.3. Organic geochemical characteristics of the source rocks in Songliao basin, northe-ast China (afte

Li, and Gao, 1985; Tables 2, 3 and 5, p. 1114 and Lil7; Wang and others, 1983, p. 126-128).

Forma'tion 

and 

Member

First member of

Qingshankou,

first member of

Nenj iang

Formations

Second and

third members of

Qingshankou

Formation

Quantou

and

Yaoj ia

Formations

Kerogen elemental 

analysis

H/C 

(Atomic

>1.4

1.00-

1.40

0.80-

1.00

<0.8

o/c

ratio)

<0. 10

0. 10-

0. 15

0. 15-

0.2

>0.2

Type 

of 

kerogen

1

A

11

B

[II

De positional 

environment 

and source 

rocks

Deep lake.

Black mudstone and

shale

Deeper lakeShallow

lake shore

Gray and

green shale

and

mudscone

Lake basin

marsh and

swamp

Grayishgreen and

reddishgreen shale

and mudstone

Organic matter

Organic 

carbon 

U)

1.5-

8.4

0.5-

1.5

0. 1-

0.5

0. l2.0

Ext r acts

>0. 1

0.03-

0. 1

0.01-

0.03

<0.01

HC 

content 

(ppm)

>1,000

300-

1,000

50-

300

<50

Group components

Saturated 

HC

39.9-

61.3

30.0-

60.0

25.7-

32.3

8.0-

28.3

Aromatic 

HC

15.2-

25.2

15.0-

21.9

15.9-

30.0

9.1-

22.3

Non-HC

12.9-

24.0

19.8-

25.3

22.7-

56.3

22.6-

66.4

HC, Hydrocarbon
rich in aromatic matter in which the vitrinite content ranges from 50 to 90 

percent. It has an H/C atomic ratio of 0.8-1.0, an 0/C ratio of 0.15-0.20, 

a hydrogen index of 100-150, and an oxygen index larger than 50.

Type III kerogen of the basin generates the least amount of hydrocarbon 

as compared with type I and type II kerogens. It is typically humic and 

consists of up to 90 percent of the vitrinite derived from higher terrestrial 

plants (Yang and others, 1985, p. 1113-1121). This type of kerogen is hydrogenpoor and oxygen-rich; the H/C atomic ratio is less than 0.8, and the 0/C ratio 

is larger than 0.2 (table 3). The hydrogen index is less than 100, and the 

oxygen index is larger than 50 (Yang and others, 1985, table 2, p. 1114).

The maturation sequences of the preceding kerogen types are determined by 

the thermal simulation experiment of kerogen and thermogravimetric analysis. 

Type I matured successively earlier than types II and III (Yang and others, 

1985, fig. 5, p. 1119 and 1121). Principal source rocks are concentrated in 

the Qijia-Gulong sag and the Sanzhao sag of the Central Depression (figs. 2 

and 3) and attain a thickness ranging from 500 to 700 m (Wang and others, 

1983, p. 203). Yang, Li, and Gao (1985, p. 1120) state that the sapropelic 

kerogen of source rocks in Songliao basin has generated more oil than gas 

with a high production capacity at the peak of generation.

During hydrocarbon evolution from the source rocks in the basin, both 

the formation temperature and the heat flux are high. The average earth heat 

flux is 1.70 x 10~" cal/cm^/sec, and the mean geothermal gradient in the main 

producing area is 4.2°C/100 m (Yang and others, 1985, p. 1120). Four stages 

of oil and gas generation are defined by Wang and others (1983, p. 128) and 

Yang, Li, and Gao (1985, p. 1119-1120) (table 4). They are the 1) immature, 

2) mature, 3) highly mature, and 4) overmature stages (fig. 2). During the 

immature stage, the kerogen begins to degrade and produces chiefly biochemical 

methane. The total hydrocarbon/organic carbon ratio maintains a relatively 

low value, and vitrinite reflectance is less than 0.5 percent (table 4). 

During the mature stage, the kerogen degrades in large quantities and produces 

mainly heavy oil. The total hydrocarbon/organic carbon ratio increases from 

about 30 mg/g to 120-160 mg/g. During the highly mature stage, kerogen is 

pyrolyzed due to the effect of strong thermodynamic action (Yang and others, 

1985, p. 1120). A large amount of light oil and wet gas is generated. The 

total hydrocarbon/organic carbon ratio decreases to less than 50 mg/g. During 

the overmature stage, hydrocarbon production is generally low, and a large 

amount of dry gas is generated. Because of the carbonation of source rocks, 

kerogen becomes black with the increase of vitrinite reflectance (table 4).

In Songliao basin, the geothermal gradient has a considerable vertical 

variation because of the thick black shale of the second member of the Nenjiang 

Formation, which is like a quilt extensively draped over the basin. Because 

this black shale has excellent heat insulation properties, and the overpressure 

occurred at a depth where the source beds are located, much heat is concentrated 

in the source beds of the first members of the Qingshankou and Nenjiang Formations (Yang and others, 1985, p. 1120). Yang, Li, and Gao (1985, p. 1120) 

indicate that the geothermal gradient of the formations above the second member 

of Nenjiang Formation is 2.7°C/100m, and below the second member of Nenjiang 

Formation it is 7.6°C/100 in the first member of the Formation and 7.8°C/100m

13
Table 4. Evolution of the source rocks in Songliao basin, northeast China (after Wang, 

Zhang, and Tan, 1983, p. 128-129; Yang, Li, and Gao, 1985, p. 1119-1121)

Stage

Immature

Mature

Highly 

mature

Overmature

Characteristics 

of oil and gas

Chiefly methane

Heavy oil

Light oil and 

wet gas

Chiefly dry 

gas

Burial depth 

(m)

<1,100 - 

1,300

1,300-1,900

1,900-2,900

>2,900

Formation 

T°C

<60-70°

70-90°

90-120°

>120°

Total hydrocarbon

Organic carbon 

(mg/g)

<30

30 increasing 

to 120-160

<50

Very low

Odd-Even 

Predominance 

(OEP)

>1.20

<1.20

1.0-1.1

Pr

Ph
in the first member of the Qingshankou Formation. In the Quantou Formation, 

the geothermal gradient is as low as 3.1°C/100m. It increases to 3.7°C/100m 

further downward to the Denglouku Formation. Yang, Li, and Gao (1985, p. 1120) 

consider this increase of geothermal gradient to be due to a high heat flux 

resulting from thermotectonic doming which had continued into the early 

phase of basin development.

The source rock and crude oil correlation in Songliao basin is shown by 

the ^3 c value of stable carbon isotope (Wang and others, 1983. table 2-4-20, 

p. 110). Yang, Li, and Gao (1985, p. 1117) have provided the ^I3 C values of 

sapropelic kerogen from the basin as -25.5 to -29.1 °/oo and that of the 

extracts from the source beds as -26.7 to -29.6 °/oo. They concluded that the 

source of the precursor of the oil was freshwater algae. Generally, typical 

characteristics of the crude oil of the basin are the high content of wax and 

nickel and the low content of sulfur and vanadium. Physical properties of 

Daqing oil are: the viscosity of crude oil at 50°C is 10-40 cp and the subsurface viscosity is 5-10 cp; the specific gravity of surface crude oil at 

20°C is 0.83-0.88; and the pour point of degassed crude oil is 25-30°C (Yang 

and others, 1985, p. 1117). Yang (1985, p. 1106-1107) mentions that during 

migration through the pores of the carrier bed, some chemical constituents 

are lost because of oil and gas absorbed by molecules on the surface of rock 

and mineral grains.

Reservoirs

The reservoir rocks of Songliao basin are fluvial and deltaic sandstone 

consisting of quartz, feldspar, and detrital elastics (Yang, 1985, p. 1103). 

Principal producing pay zones, however, are composed chiefly of delta front 

fine-grained sandstone (table 5). Major reservoirs are the Heidimiao, Shaertu, 

Putaohua, Gaotaizi, and Fuyu in the Central Depression; and the Yangdachengzi 

and Nongan in the Southeast Uplift (fig. 3) (table 2) (Wang and others, 1983, 

table 4-9-1; Ma, Yang, Ding, and Guan, 1984, fig. 1). Wang and others (1983, 

p. 240-241), Ma, Yang, Ding, and Guan (1984), and Yang (1985) grouped these 

reservoirs into the upper assemblage of the Heidimao; the middle assemblage 

of the Shaertu, Putaohua, and Caotaizi; and the lower assemblage represented 

by the Fuyu, Yangdachengzi, and Nongan. The highest producing pay zones of 

the basin are from the Shaertu, Putaohua, and Gaotaizi reservoirs (Yang, 

1985, p. 1103). In descending order, discussion of these reservoirs follows.

The Heidimiao reservoir of the upper assemblage consists chiefly of the 

floodplain, distributary channel, and delta-front deposits of the poorly to 

well-sorted, fine- to medium-grained sandstone of the third and fourth members 

of Nenjiang Formation (table 2). Oil and gas were generated from the first 

and second members of the Nenjiang, trapped by lithofacies changes and fault 

barriers in syncline, and sealed by shale and mudstone of the fourth and 

fifth members of this formation (Wang and others, 1983, p. 240-241; Ma, Yang, 

Ding, and Guan, 1984).

The Shaertu, Putaohua, and Gaotaizi reservoirs of the middle assemblage 

consist chiefly of delta front and prodelta to offshore lacustrine deposits 

of fair to well sorted fine-grained sandstone of the Daqing delta complex 

(tables 2 and 5). These three reservoirs, of about 5 billion barrels of oil,

14
provide the principal pay zones for the Daqing oil field. Among them, the 

Putaohua reservoir contains up to 70 percent of the total, or 3.5 billion 

barrels of oil (Ma, 1985, p. 1123). The thickness of the reservoirs gradually 

decreases from the northern delta front to the southern prodelta area accompanied by an increase in the number of sandstone beds as well as of a decrease 

in the thickness of the individual sandstone beds. As the shale content 

increases southward, the porosity and permeability of the reservoir sandstone 

become poorer (table 5).

Daqing oil field is located in the Daqing central basin high of the 

Central Depression (fig. 6). The Daqing central basin high contains seven 

oil and gas pools, which, from north to south, are named and shown in figure 1 

of Yang's report (1985, p. 1102): Lamadian, Shaertu (Saertu), Xingshugang, 

Gaotaizi, Taipipingtun, Putaohua, and Aobaota. Each of these pools is confined 

in an anticline structure and is made up of the Shaertu, Putaohua, and Gaotaizi 

pay zones; vertically, the distribution of the oil and water is shown with the 

appearance of an upper thickened oil section over an oil-water transition 

section, and the properties of crude oil change greatly from the inner oilbearing limit, laterally becoming quite poor (Yang, 1985, table 1, p. 1102). 

The effective source beds for generating oil and gas deposits of the Daqing 

are the shale and mudstone of the first, second, and third members of the 

Qingshankou Formation and the first member of the Nenjiang Formation (table 2) 

(Wang and others, 1983, table 4-9-1, p. 241). Oil and gas were expelled from 

the source rocks and migrated through the sandstone carrier beds, as well as 

the structural fractures, to enter the traps and then accumulate in the 

reservoirs. Generally, in the Daqing basin high, the oil and gas were sealed 

by shale and mudstone of the second member of the Nenjiang Formation (Yang 

and others, 1985, p. 1120-1121). In the north part of the Daqing high, oil 

and gas were trapped by an anticlinal structure, locally, with northeastern 

strike-slip fault barriers, whereas in the south part of the area, they were 

trapped in lenticular and sheet sandstone bodies by lithofacies changes associated with anticline structure and growth fault barriers (Yang, 1985). However, 

in the surrounding sags of the Daqing basin high, the oil and gas occur in noselike structures of syncline folds (Yang, 1985; Ma, 1985). Yang (1985, p. 1110) 

concludes that the stages of oil and gas generation, expulsion, secondary migration in carrier beds, and accumulation in the reservoir occurred concurrently 

with the development history of structural trap growth in the Daqing area 

during the time span from the Late Mingshui to the Late Yian (table 2).

The Fuyu, Yangdachengzi, and Nongan reservoirs of the lower assemblage 

consist of fluvial and deltaic deposits of fine-to-medium lenticular and sheet 

sandstone bodies of the Quantou Formation (table 2). Generally, the porosity 

averages about 20 percent and permeability averages about 150 md. These 

reservoirs occupy a north-south basement high area with a relatively thin 

earth's crust in the central part of Songliao basin (figs. 2 and 6). Source 

rocks of the Fuyu and Yangdachengzi oil and gas deposits are chiefly of the 

Qingshankou shale, oil shale, and mudstone; the Nongan oil and gas deposits 

are generated from the shale and mudstone, probably of the Lower Cretaceous 

Denlouku and Upper Jurassic ages (table 2). In addition, the mudstone, shale, 

and oil shale of the fourth member of the Quantou Formation generates oil 

and gas deposits for all three reservoirs (table 2) (Ma, Yang, Ding, and Guan, 

1984, p. 11). The oil and gas in these reservoirs were sealed by mudstone

15
Table 5. Depositional environments and physical properties of the reservoir sandstone i

complex of Songliao basin, northeast China (modified after Wu, 1982; Ma, 1985)

Depositional

environments

Deltaic

plain

Delta

front

Prodelta

to

Offshore

lake

Thickness

(m)

Gross

10

6-16

4-6

Individual

4-8

2-6

3

Porosity

(%)

22-25

20

Permeability

(md)

300-800

300-400

Shale

content

(%)

12-14

18

Age

2nd and 3rd

members of

the Qingshankou

Formation

upward to

1st, 2nd, and

3rd members

of the

Yaoj ia

Formation

(table 2)

R

Distrib

paralle

bottom, 

lenses; 

Shale a

channel

Princip

bars wi

subaque

and len

channel 

upward, 

water a

source 

Yaojia-

the Put

200 km 

fine-gr

1982, p

1125) 

Ui

ftt
and shale of the Quantou Formation and trapped by anticline and nose-shaped 

structure locally, with fault barriers along the slopes of the structural 

high (table 2). In the Fuyu, Mutou and Xinli oil fields (Ma, Yang, Ding, and 

Guan, 1984; fig. 16), the oil and gas also were trapped by fault barriers in 

the updip and by lithofacies changes in the downdip (Ma, Yang, Ding, and Guan, 

1984, p. 11-17). The exploration for oil and gas deposits of the lower 

assemblage reservoirs is still in a preliminary stage, and it is expected 

that further exploratory drilling will discover new oil and gas pools in 

those reservoirs (Ma, Yang, Ding, and Guan, 1984, p. 15-17).

Potential

Petroleum potential of Songliao basin is substantial. Principal producing 

oil and gas fields are concentrated in the central and southeastern parts of 

the basin. Of these, Daqing oil field of the Daqing central basin high in the 

Central Depression ranks as one of the world's giant oil fields and has produced an average of more than 1 million barrels of oil per day since 1976, 

about half of China's daily oil production. Original oil in-place at Daqing 

is estimated to be about 21.9 billion barrels, of which 30 percent is likely 

to be recovered by existing production methods; enhanced recovery processes 

are currently being considered for use in Daqing field (International Encyclopedia, 1985, p. 10-11 and 21).

Generally, detailed stratigraphic information and data on exploratory 

drilling are not available within individual structural units of the basin; 

therefore, an estimate of the ultimate petroleum recovery from the basin is 

not provided in this report. The author believes, however, that future new 

discoveries are favorable in the delta-front sandstone of the Quantou and 

Denkouku Formations in the southern part of the basin.

SUMMARY AND CONCLUSIONS

Songliao basin of Northeast China evolved on a Variscan folded eratonic 

basement by extensional continental fragmentation during the latest episode 

of the Late Triassic Indosinian orogeny. Subsequently, Songliao reached 

its full development stages through extensional graben-faulting from Late 

Jurassic to Early Cretaceous and growth faulting in the Middle Cretaceous. 

The basin acquired its present configuration by extensional tectonics during 

the Late Cretaceous Yanshanian and the Cenozoic Himalayan orogenies.

In the Middle Cretaceous, the basin reached the full development stage 

during the lacustrine-fluvial sedimentation of the first members of the 

Qingshankou and Nenjiang Formations. In high-water stages of the first members of these two formations, the lake covered an area ranging from 87,000 to 

200,000 km^ and was fed by the influx of detrital sediments from the adjacent 

highlands. The depocenters of these members coincided with the subsidence 

center of the basin along a north-northeast linear rift of the Qijia-Gulong 

and Changling sags in the Central Depression. The lake water hence was enclosed in an anaerobic environment favorable for the preservation of organic 

matter, forming an excellent source for petroleum generation.

16
The lipid-rich kerogen types I and IIA generated most of the hydrocarbon. 

Maturation sequences of kerogen types are determined by Yang, Li, and Gao 

(1985, p. 1119 and 1121) to be the type I which matured successively earlier 

than types II and III. Principal source rocks, 500 to 700 m thick, are confined to the first members of the Qingshankou and Nenjiang Formations and are 

concentrated in the Qijia-Gulong and Sanzhao sags of the Central Depression. 

The sapropelic kerogen source rocks have generated more oil than gas with a 

high production capacity at the peak of generation.

During the hydrocarbon evolution from the source rocks, both the 

formation temperature and heat flux were high. The geothermal gradient has 

considerable vertical variation because of the thick black shale of the 

second member of Nenjiang Formation, which is like a quilt extensively draped 

over the basin providing excellent heat insulation (fig. 2).

The reservoir rocks of the principal producing pay zones consist chiefly 

of delta front fine-grained sandstone. The greatest producing pay zones of 

the basin are in the Shaertu, Putaohua, and Gaotaizi reservoirs of the Daqing 

delta complex in the Central Depression. Daqing delta formed and developed 

during a period between two major high-water events as indicated by the 

first members of the Qingshankou and Nenjiang Formations. The delta sandstone 

was deposited on a gentle paleoslope and consists of more than 200 lobes 

extending into the center of the basin with a total thickness of 500 to 600 m 

in an area approximately 20,000 to 44,000 km^. Of these lobes, the Yaojia-1 

lobe is about 200 km long and the major sandstone body of the Xingshugang 

delta, which contains the most productive pay zone of the Putaohua reservoir. 

The Putaohua reservoir ranges from 40 to 60 m thick (Ma, 1985). In the 

reservoirs oil and gas are trapped by anticlinal and nose-shaped folds, 

fault barriers, and lithofacies changes, and sealed by shale and mudstone. 

During the time span from the Late Mingshui to the Late Yian, simultaneous 

oil and gas maturation, expulsion, migration, and structural trap formation 

were responsible for the formation of the Daqing giant oil field.

The petroleum potential of the basin is substantial. International 

Encyclopedia (1985) lists the original oil in-place at Daqing at about 21.9 

billion barrels. The author believes that future discoveries are favorable 

in the deltaic sandstone of the Quantou and Denlouku Formations in the southern 

part of the basin.

17
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19