MORE DATA DISCLOSED ON KAZAKHSTAN BLOCKS

Easternoil Services Ltd., Surrey, England, has disclosed more details about the region covered by its planned upstream joint venture in Kazakhstan, U.S.S.R. The four prospective joint venture areas cover 33,350 sq km in the pre-Caspian depression of Uralskaya Oblast (see map, OGJ, Sept. 16, p. 38).

Sept. 30, 1991

3 min read

Easternoil Services Ltd., Surrey, England, has disclosed more details about the region covered by its planned upstream joint venture in Kazakhstan, U.S.S.R.

The four prospective joint venture areas cover 33,350 sq km in the pre-Caspian depression of Uralskaya Oblast (see map, OGJ, Sept. 16, p. 38).

Early joint venture development is expected to focus on Upper Permian and Neogene sediments at 1,500-6,000 ft on Block 2, most of which has been covered by seismic surveys. Drilling on Block 2 has confirmed seven oil and gas producing structures with proved reserves of 186 million bbl of oil equivalent (BOE), said Ernest E. Cook, an Easternoil director.

Other structures have been identified in the southern part of Block 2, each with estimated average reserves of 60-68 million BOE, he said.

R. Prevalsky, chairman of Easternoil, previously reported combined estimated reserves of as much as 1 billion BOE on the four tracts.

Easternoil and two Kazakh S.S.R. oil and gas organizations, collectively called Uralskgeo, will be partners in the proposed joint venture. The prospective partners expect to sign joint venture documents within the next 18 months.

Geological and geophysical data are scarce in Blocks 1, 3, and 4, Cook said. However, easy terrain will allow fast, low cost exploration.

Some seismic data are available in the western part of Block 1 and northern part of Block 3. Very little geophysical exploration has occurred in Block 4. An undisclosed number of wells has been drilled in Block 1.

The prospective license areas have roads, railroads, and oil and gas pipelines.

Cook also is chairman of Gandalf Explorers International Ltd., Houston, Easternoil's U.S. representative.

PRE-CASPIAN DEPRESSION

Cook's data show the pre-Caspian depression is bounded on the north by the Ural homocline, on the east by the Ural fold system, on the southeast by the Turan plate, and on the southwest by the Skitian plate. It is filled with Devonian to Neogene sediments.

In the central depression, sedimentary sections are estimated to be as much as 49,000-52,000 ft thick. Lower Permian halite sediments in the central part of the depression in later stages of development have formed salt structures 19,500-23,000 ft thick, Cook said.

Much of pre-Caspian basin's oil and gas potential is thought to be in postsalt Upper Permian and Neogene sediments at 2,600-16,375 ft. Analyses show two exploratory complexes: Upper Triassic, Jurassic, and Cretaceous shales, and Upper Permian and Triassic sediments.

The complexes have different geological structures and different oil and gas traps, Cook said. So they require separate approaches to evaluation and exploration.

Although not well known, zones at 16,000-19,650 ft in Blocks 1 and 3 on the flanks of the depression and on the Akhtyubinsk-Astrakhan uplift in Block 2 are thought to be the best presalt oil and gas sediments.

Devonian terrigen-carbonates in the Paleozoic section contain as much as 2.5% saporpel-humus organic matter, Cook said. Lower Carboniferous sediments contain similar organic matter in the same proportions.