Abstract

Pogodaevo-Ostaf'evsky depression is situated in northern board of Pricaspian syneclise. It is unrequited late devonian - tournaisian depression, which succeed to ancient Perelyubskiy depression of basement. This depression is filled up by strong (400 m) terrigenous deposits vezenian age (kos'vinsko-radaevskie deposits). On territory of Pogodaevo-Ostaf'evsky depression oil-and-gas fields not yet discovered, but on nearby territory are finded oil inflows from similar sediments. Prospects of oil-and-gas content of depression are connected with three complexes: late devonian - tournaisian, kos'vinsko-radaevskij, and probably, bobrikovian. Opening of oil-and-gas fields in an onboard zone of depression is connected with reefs bodies late devonian - tournaisian age.

Also prospects of territory should be connected with zones of beds thinning on depression board's vezenian thicknesses of compensation. These deposits can be perspective and in an internal zone of depression where their thickness is increased. Conceivably, bobrikovskie deposits have oil-and-gas content (by analogy with Muhanovo - Erohovskij depression where bobrikovskie sandy layers have oil-and-gas content) are presented by covering structures above barrier reefes.

At present by seismic data have been evolved perspective objects on Zapadno - Ovchinnikovskoj, Ovchinnikovskoj, Lebedevskoj, Malozajkinskoj, Novotrudovoj, Severno - Talovoj, Talovoj, Yuzhno - Talovoj areas. These are the bodies of the small size located in a zone of reef benches. Reseched territory - northern board of Pricaspian syneclise, zone of a joint it's with Volgo-Ural'skaya anteclise.

Late devonian - tournaisian reef bench, traced in the given territory, on a significant extent it is regressively built on by the vizenian-bashkirian barrier, and they create uniform sedimentary bench. This barrier reef forms boards of Pogodaevo-Ostaf'evskij not compensated paleodepression, inheriting Perelubskij sag of the base.

Introduction

Depression is situated on northen board of Pricaspian syneclise, representing far incurrent area paleoshelf, its deep-water gulf generated in famennian - tournaisian? time and compensated powerful terrigenous thickness of carboniferous sediments.

Depression is situated on territory of South - Buzuluk oil-and-gas province and estimates as a perspective oil-and-gas object.

Most of reseaches estimates depression by analogy with Muhanovo - Erohovskij depression (Orenburg area), which reef boards controls most of oil pools, in which the most part of industrial resources of the Orenburg area (about 50 percent) contains.

Statement of Theory and Definitions

The main structural element of this area - the basic onboard bench of Pricaspian syneclise, precisely traced on a surface of palaeozoic sediments; this bench is considered as northern border of depression, separating it from Volgo - Ural'skaja anteclise and dividing northern onboard zone on an external part and internal.

The main tectonically elements of consider territory is Klincovskij and Karpovskij ledges of base. Settling down to the north Irgizskij sag, being element of Buzuluk depression; Talovo - Dolinnaya and Chinarevsko - Koshinskij zones of raisings (fig. 1).

In structural plane the main part of considered territory located on south area of Buzuluk depression, limited from north Kamelik - Chaganskoj flexure-fault zone; from the east and the West - slopes of Orenburg and Pugachev arches, accordingly.

The surface of the base buries on the northern board of Pricaspian syneclise from 2500 - 3000 m to 6000 m and deeper. The same situation can be seen on the surface of carbonate rocks eyfelian stage.

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