29 - July 17th thru July 21st 2000, Vol X

 

  

 

 

OIL AND GAS PROSPECT IN THE YEMENI SECTOR

OF THE RUB AL-KHALI BASIN
 


Wang Xikui* and Nedham Mohammed Darsi**
(Changchun University of Science and Technology, 130026, China)

ABSTRACT
This is the first paper, which discusses the Oil and Gas Prospects in the Yemeni Sector of the Rub al Khali Basin on the basis of a new look to the area. This new look to the area depends:
1. The geological research history work in the area,
2. The neotectonic movement,
3. The new crust movement,
4. A collection of satellite images, which had been taken of the Republic of Yemen during the period from 1994 to 1997 with hundreds of airophotos and satellite images, taken to different part of the Peoples Republic of China. (As an exemplars to find a case study to the Yemeni Sector of the Rub al Khali Basin). And this led us to introduce a new idea for a new project, which we hope is going to help future petroleum exploration activities and attract foreign exploration investment to work in the Yemeni sector of the Rub al Khali Basin.

1 INTRODUCTION:
It is known that one of the world's largest exploration successes of the 1980s was the discovery, by Canadian Occidental and partners, of constellation of oil pools in the Masila region of Yemen. The presence of several hundred million barrels of recoverable oil has been proved by drilling within reservoirs ranging in age from Jurassic to Cretaceous, with most reserves in Lower Cretaceous sandstone of the Qishn Formation. The discovery of commercial oil and gas in several interior Mesozoic rift basins of Yemen in the late of 1980s and in the early 1990s after the Yemeni unification, spurred many oil companies to enter the exploration race and carry out detailed seismic surveys. This led to intensive explorations drilling in many areas. The Yemeni sector of the Rub al Khali Basin, the main subject of this paper, is one of those areas, which found some care in the past and attracts many oil companies in the present time.
Note (1): (a) Al-Ghawar oil field one of the world's largest oil fields has been found in the Rub al Khali Basin. (b) Oil, which is exploited in that's area is of excellent quality. (c) Oil Companies, which drilled exploration wells in the Yemeni sector of Rub al Khali basin (in Qinab, Hathout and Shahr area), had penetrated Paleozoic clastic reservoirs with core porosity ranging between 5% and 25%, 120 md to 3200 md permeability and age from Middle Cambrian to Early Permian. (d) The Qusayba (lower Silurian) shales, which is the principal source rock for Paleozoic discoveries in Saudi Arabia is present in the above mentioned areas. (e) Much of the southern flank of the basin lies within northeastern Yemen, with the regional Paleozoic Hadramawt Arch forming the southern basin margin onto which all Paleozoic and Early Mesozoic sedimentary sequences pinch out. (f) Northward into the basin, the flank slopes gently but in a step-like manner and the sedimentary column thickness increases from about 2 km near the crest of the Hadramawt Arch to over 4 km by the Yemeni-Saudi border.

2. PERVIOUS ACTIVITIES:
According to Nedham Mohammed Darsi** division of the geological research history work in the Republic of Yemen can be classified to four stages (See Yemen Times Newspaper. Issue 2-January 10th through January 16 2000, Vol. IX, Culture Page, Issue 10 - March 6 through March 12 2000, Vol. X, Culture Page and Issue 15 - April 10 through April 16 2000, Vol. X, Culture Page). It is so clear now, that: 1. On the First Stage (The First Systematic Geological Observation Stage or Carter's Stage), 1852-1901:

No kind of geological studies had been detected in the area.
1. On the Second Stage or the Hinterland Studies Stage, (1902-1946) and the Third Stage (The First Systematic more detailed Stratigraphic and Geological Studies Stage or Beydoun, Z.R.'s Stage, (1947-1967): Geological field investigation, supplemented by photogeologic and ground mapping covering the entire territory, were carried out by the Petroleum Concessions Ltd, one of the Iraq Petroleum Company associated companies (IPC and Associated companies) between 1937 and 1960.
2. On The Third Stage (The First Systematic more detailed Stratigraphic and Geological Studies Stage or Beydoun, Z.R.'s Stage), 1947-1967: Bunker, D.G. wrote about the southwest Borderlands of Rub al Khali, in 1953. From 1961 to early 1967, Pan American International Oil Company through a subsidiary, Pan American Hadhramawt Oil Company (PAHOC) drilled four wells (Hoowarin, Tarfayt and Core Hole 88 reached Precambrian basement and the forth was abandoned in the Cretaceous sediments).
3. The Fourth Stage or The Yemeni Geologists Stage (1968 until Today):
3.1. It is known that, the Petroleum and Minerals Board (the PMB) was established, in 1970 in former South Yemen. During the period from 1970 to 1973, the joint of former South Yemen-Algerian Petroleum Company (SYAPCO) drilled Taur-1 in 1974 and Taur-2 was commenced. In 1974, a group of experts from Cuba assumed the drilling operation from SYAPCO and with former PMB completed Taur-2, Taur-3 and drilled Thamud-1 and Hathout-1. In September 1976, the functions of the PMB were broadened and the Petroleum Exploration Board (the PED) was created (The Petroleum Exploration and Production Board, Aden Branch As known now), led different activities on studying the geology of this area. As a result of their work on the Yemeni sector of Rub al Khali basin, wells as Taur-2, Taur-3 and Hathout-1 was drilled. A group of the P.E.D.'s Engineers, Technician and workers, work hard on this area, and their work is highly appreciated. On Mar. 27 1979, B. Kuzin and Mohammed Ba'abad made a Stratigraphic Correlation, for wells drilled in that area correlative with wells located in the adjacent area at that time.
Note (2): The Petroleum Exploration and Production Board (P.E.P.B.) is responsible for all petroleum exploration and related activities and is interested with the exploration for oil and gas in the Republic of Yemen on its own, or in association with foreign companies through production sharing agreements. The P.E.P.B. has a professional staff and other administrative personnel.
3.2. Between 1975 and 1979, as a part of its assistance program, TechnoExport, the former Soviet Technical Assistance Organization, had recorded aeromagnetic surveys covering most of former South Yemen and also a gravity survey had been conducted over specific areas of interest. CDP reflection and refraction seismic had been concentrated in the Yemeni sector of Rub al Khali basin and as a result of their work in the area, wells as Hathout-2 Shahr-1 were drilled in 1981-82.
Note (3): The field investigation had been augmented from time to time by Czechoslovakian and German technical personnel.
3.3. In the Yemeni sector of the Rub Al-Khali basin, first Bahad flower structure was detected from the seismic interpretation and then later Qinab flower structure had detected from the seismic interpretation by Elf Acquitaine Petroleum B.V, during the first phase of exploration in their ex-block 11, in 1989.

3. THE RUB AL-KHALI SAND DESERT:
The Rub al Khali sand desert or the Empty Quarter (as also known) is a huge region of sand covering about c.225, 000-sq. mi. (582,750 sq. km). It is one of the largest sand deserts in the world and the great desert of the Arabian Peninsula. Thdesert occupies much of the southern interior of the peninsula, from the highlands of the Nejd (to the north) to the plateaus of Hadhramawt (to the south); it slopes from an altitude of 3,300-ft (1,006 m) in the west to near sea level in the east. The sand dunes in the Rub al Khali sand desert rise to over 660 ft (200 m) in the southwest and mainly distributed in parallel to sub parallel ridges (called uruq), separated by narrow flat stretches of gravel, gypsum, or silt (shuquq). The trend of the southern border of the desert is east-northeast, which is also roughly the trend of the dune ridges. Slip faces of the dunes are generally south, but some north-facing slip faces have been observed. Some migration of dunes takes place; however, the migration seems to be up by seasonal wind directions, so that migration in any specific direction is difficult to detect; there are salt marshes and pans in the southeast. Rub al Khali is connected to the Nafud desert in the north by the Dahna, a narrow corridor, 800 mi. (1,287 km) long. The desert comprises more than 25% of Saudi Arabia. It is extremely dry and virtually uninhabited. Only the southernmost fringe of which reaches into the Republic of Yemen. A much smaller area is the Ramlat Sabatayn sand desert. It stretches eastward from the foothills in the north part of the Republic of Yemen and in Bayhan province, where it is some 100 kilometers wide, into the Hadhramawt drainage basin, occupying roughly the western extension of the Wadi Hadhramaut structural trough. The dunes lose both height and lateral extent eastward, until they die out as low isolated patches of sand some five kilometers in width near Shibam in Wadi Hadhramaut. The Ramlat Sabatayn area is again one of dune ridges which, however, are less regular than those of the Rub al Khali with a trend roughly east-northeast in the west, are some 50 meters in the height, and are eastward and become irregular toward the east. Migration of the sand is largely offset by seasonal changes in the prevailing winds and by thermal disturbances.

4. THE YEMENI SECTOR OF THE RUB AL-KHALI BASIN:
Several depressions are superimposed on the Arabian Shelf and at one time for another have received thick deposits relative to adjacent parts of the platforms. Such basinal sags have formed in the northeastern Rub al Khali, northern Persian Gulf, Dibdibah, and Sirhan Turayf areas. Seismograph and structural drill work in the Rub al Khali Basin have outlined an elongate basin. Width of the basin is relatively uniform throughout its length, eraging about 300 km. It is known that the Yemeni sector of the Rub Al-Khali basin forms the southern flank of this huge structural downwarp, which originated in the early Paleozoic as intracratonic sag later in the Paleozoic. This feature is bounded on the north by the sand dunes of the Rub al Khali and on the south by the
Ramlat Sabatayn sand desert. Much of the southern flank of the basin lies within northeastern Yemen, with the regional Paleozoic Hadramawt Arch forming the southern basin margin onto which all Paleozoic and Early Mesozoic sedimentary sequences pinch out. Northward into the basin, the flank slopes gently but in a step-like manner and the sedimentary column thickness increases from abut 2 km near the crest of the Hadramawt Arch to over 4 km by the Yemeni-Saudi border.

5. SATELLITE IMAGES INTERPRETATION
According to our study on a collection of satellite images, which had been taken to the Republic of Yemen during the period from 1994 to 1997 and hundreds of airophotos and satellite images, which had been taken to different part of the Peoples Republic of China. We concentrated our attention onto the following more important satellite images, due to:
5.1. Those satellite images were related to the Yemeni sector of the Rub Al-Khali basin.
5.2. The very clear images of different faults types shown on the surface, which we classified them according to their directions and trend, to:
First type: Faults with a NESW directions (very clear on the satellite images).
Second type: Faults with EW and ENE-WSW directions (clear to very clear on the satellite images).
Third type: Faults with an NS and NNE-SSW directions (clear to very clear on the satellite images)
Forth type: Faults with a NWSE directions (clear to a little clear on the satellite images).
5.3. According to the character of the Satellite images, we found a black material filling these faults on the surface, which looks like natural asphalt (?). Here we want to drew People, who are interested in this field on the following fact:
The same example was found in Kelamayi oil field, a famous oil field in the Northwest of the Peoples Republic of China, located to the margin of Zhunger Basin (Jurassic Formation oil and gas bearing layer, oil and gas stored in overthrust structures). This oil field first time discovered by the local villagers, who found that black material on the surface and then known as asphalt.

6. NEW LOOK TO THE AREA
Based on our study to the geological research history work, the neotectonic movement, the new crust movement, and our interpretation for the satellite images, we have a new look to the area. This new look to the area depending on our new thinking, that during the successive rift phases, (The Karroo Rift Phase; The Somali Rift Phase; The Mascarene Rift Phase; The Yemen Rift Phase), the expected main extensional faults trend and the minor extensional faults trends changed their direction.

Especially, during the recent time, where we find that:
1. The first type of faults, which has the NE-SW directions, is a normal and oblique normal fault.
2. The second type of faults, which has the EW and ENE-WSW directions, is a divergent sinistral wrench faults and has the same trend of the southern border of the desert, which is also roughly the trend of the dune ridges.
3. The third type of faults, which has the NS and NNE-SSW directions, is divergent dextral wrench faults.
Note (4): The second type of faults and the third type of faults are a share faults type, with right and left hands.
5. The forth type of faults, which has NWSE directions, is over thrust faults.

CONCLUSION
1. As a result of our study, we think that a new rift phase started in the area during the recent time.
2. On this new rift phase:
a. The first type of faults, which has the NE-SW directions, is a normal and oblique normal fault. They are parallel to the direction of the largest principle stress of the Arabian plate.
b. The forth type of faults, which has NWSE directions, is over thrust faults. Their extensional fault trend resulted by the largest principle stress of the Arabian plate.
3. We think, that this new stage has the same main rift trends like the Karroo rifts phase (?).
4. The natural asphalt (?) shown on the surface of this area by the satellite images might be a very clue for looking for a new petroleum discoveries.

RECOMMENDATION
1. It is recommended that a very highly qualified team study the Yemeni sector of Rub al Khali basin for recognition of crustal zones of weakness, their trend and origin is thus of vital importance in the interpretation of rift structures. We believe that this area, which took some care in the past and attracts many experts in the present time, is not going just to surprise all with its oil and gas discoveries, but also with its very rich geological data in the future.
2. The most important thing, that we want to drew the Ministry of Oil and Mineral Resources, foreign companies and all who are interested in this area to concentrate their exploration attention on the following two coordinate points and the adjacent area around them:
First Point: N 18.46O / E 51.05O
Second Point: N 18.22O / E 49.67O

REFERENCES:
1. Beydoun, Z.R., As-Saruri, M.L., and Baraba, R.S., 1996. Sedimentary basins of the Republic of Yemen: their structural evolution and geological characteristics. Revue de I'Instit. Francais du Petrole, 51, No.6, Nov.-Dec. 1996.
2. Bunker, D.G., 1953. The Southwest Borderlands of Rub al Khali: Geol. Jour. v. 19, pt. 4, p. 420-430.
3. Dyer, R.A. and Husseini, M.I., 1991. The western Rub al-Khali Infracambrian graben system. Proceedings SPE Middle East Oil Show, Nov. 1991, Bahrain, 505-512 (SPE 21396).
4. Mills, S.J., 1992. Oil discoveries in the Hadhramaut: how Canadian OXY scored in Yemen. Oil and Gas Journal, (9 March 1992), 49-52.
5. Nani A.S.O., 1998. Miscellaneous Scientific Articles on geology and hydrocarbon exploration in Yemen (Flower Structure in the Yemeni Sector of the Rub al Khali Basin and Paleozoic clastic reservoir in Oman, Saudi Arabia and Yemen).
6. Nedham, M.Darsi, 2000. The Geological Research History Work in the Republic of Yemen during the period from 1852 until Today (Three papers). Yemen Times newspaper. Issue 2-January 10th through January 16 2000, Vol. IX, Culture Page, Issue 10 - March 6 through March 12 2000, Vol. X, Culture Page and Issue 15 - April 10 through April 16 2000, Vol. X, Culture Page.
7. Peter E. Putnam, George Kendall, and David A. Winter, 1997. Estuarine Deposits of the Upper Qishn Formation (Lower Cretaceous), Masila Block, Yemen. AAPG Bulletin, V. 81, No.8 (August 1997), P. 1306-1329.
8. The Columbia Encyclopedia, Fifth Edition Copyright 1993, Columbia University Press. Licensed from Inso Corporation.

ABOUT THE AUTHOR
* Wang Xikui graduated from Changchun University of Science and Technology in 1982 and got his Doctor degree from Lanzhou Institute of Desert, the Chinese Academy of Sciences in 1995. He studied and worked as a postdoctoral student in Changchun University of Science and Technology from 1997 to 1999. His scientific interest is Concentrated on the neotectonic movement and petroleum resources, Quaternary Geology and geomorphological system modeling.
** Mohammed Darsi graduated from the Russian among People Friendship University in 1991 as a Petroleum Engineer, Geologist (M.S. degree). He began his professional career by working as petroleum engineer, geologist in the Petroleum Exploration and Production Board (Aden Branch). His scientific interest is concentrated on the Geological Research History Work, Earth science software application and basin-modeling problems.

 

 

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