Geology, geography and global energy

Scientific and Technical Journal

Specific geological of the devonian dofamenckih deposits Astrakhan arch

2014. №1, pp. 122-135

Pisarenko Yuriy A. - Head of Department, Lower Volga Research Institute of Geology and Geophysics, 70 Moskovskaya st., Saratov, 410710, Russian Federation,, pisarenko@nvniigg

Pykhalov Viktor V. - C.Sc. in Technical,Associate Professor, Astrakhan State Technical University, 26 Tatishchev st., Astrakhan, 414000, Russian Federation,, viktor.pihalov@yandex.ru

Devonian sediments before famen at different depths studied by several parametric wells. Their presence has been proven by drilling intervals with good collectors tributaries without sulfur dioxide (methane) at great depths. Clarification of the stratigraphy exposed drilling deposits, as well as their identification with the seismic boundaries leads to the need to revise existing geological representations about the history of the Devonian sediments and distribution before famen potential pitfalls of hydrocarbons (HC). According to the model constructed allocation interval 6500 (6300 m) – 6180 m folded mainly allochthonous terrigenous rocks of Middle to look properly. Probably, here we are faced with inaccuracy in the interpretation paleofaunistic definitions. Error in determining the age of rocks on the results paleofaunistic definitions, probably due to the fact that species determinations were made on the balance of poor preservation, and in some cases, because the samples were obtained from the slurry, such definitions should recognize sufficiently reliable. Also found in the core, lifted out of the hole D-2, in the interval 6180–6300 m fauna form a transit – that is existed in the Early and Middle Devonian in time. In accordance with the existing concepts, the main gas potential in the Devonian sediments before famen associated with traps confined to anticlinal structures and bioherms folded rocks with low reservoir properties. If assume that the porosity of rocks composing bioherm, by analogy with limestone lohkovskogo tier penetrated by the borehole D-2 may be greater than 18 %, the average bioherm resources estimated at more than 400 billion m3. As a result of the research was built a new model of the geological structure of the Devonian sediments before famen. According to this model, large gas accumulations can be expected in traps associated with reef bodies in the Lower Devonian (lohkovsky tier) and Middle Devonian sediments.

Key words: Astrakhan arch,structural features,drilling wells,gas-bearing,mudstone,limestone,deposits of the frasnian stage,sediment ems tiers,tier lohkovskogo deposits,deposits devonian,department of middle devonian sediments,

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