Natural monuments


Saatly ultradeep well


Saatly ultradeep well SG-1 was projected during the existence of the USSR according to the Programme of ultradeep drilling pursued by Ministry of Geology of the USSR.


The target depth of SG-1 was 15 km. It was located near Saatly city, 10 km southward of epicenter of Saatly - Kyurdamir gravity maximum where depth of the consolidated crust surface - of the supposed "basalt layer" according to the data of deep seismic sounding (DSS) with the application of reflected and diffracted waves was estimated 6-7 km.


The drilling started in 1977 and for technical reasons it was stopped in 1982; depth of the well bottom was 8324 m.


Objective of the drilling:
  • construction of geophysical model of the Earth crust within the intermontane depressions;
  • determination of peculiarities of manifestation of endogenic processes in deep areas of the Earth crust;

The well reached the following sections

1

loams, sandy loams and pebbles
in the sea terraces

Quaternary

860 m

2

clays, sandstones

Absheron stage

1070 m

3

clays, sandstones

Akchagyl stage

320 m

4

clays, sandstones

Balakhan stage (productive series)

530 m

5

clays, sandstones

Late Miocene, Sarmatian

50 m

6

limestones with dolerite sills

Early Cretaceous-Late Jurassic

710 m

7

basalts with dolerite sills

Jurassic

1270 m

8

andesite-basalts and andesites
with gabbroid sills

Jurassic

2000 m

9

andesites-dacites, dacites, rhyodacites
with dolerite sills

Jurassic

1514 m

Total thickness:  8324 m



In interval 6552-6561 m there occurred a horizon of siliceous tuff-aleurolites with radiolarite fauna, Middle Jurassic. Not intensive oil seeps were only recorded in the productive series (2707-m depth). As a result of the stuffy of the hole and core of SG-1 it was determined:


1. phenomenon of the descending filtration of the ground waters accompanied by lateral or descending migration of microelements and hydrocarbons may result in the localization of the latter in non-traditional reservoirs;


2. distinct antidrome evolution of he Mesozoic volcanism: dacite-andesite - andesite-basalt - basalt series corresponding to volcanism in transitional setting from rift-continental to island-arc regime by conditions of formation;



3. two zones with abnormal physical properties of rocks (decreased values of velocity of primary waves; solid-phase density and increased values of the effective porosity: in the top of volcanites of the Mesozoic base (3540-4060 m) and along the contact of heterogeneous Jurassic volcanogenic series (7100-7400 m);
 

4. metamorphic zonation - zeolitic (3540-4600 m); prenite-pumpellite (4600-6800 m); green-shale (6800-8324 m) demonstrating lowering of hydration of rocks with the growth of depth;


5. possibility of everywhere spread of disconsolidation zone in the top of the buried Mesozoic base;



6. three horizons of actual and potential oil and gas content:


  • the upper horizon (0-3.5 km) - Neogene series of the sedimentary cover; commercial deposit is localized in anticline structures;
  • the middle horizon (3.5-5.0 km) - Eocene series and deconsolidated top of the Mesozoic base; commercial deposits in local protrusions of the base;
  • the lower horizon (8.5-9.5 km) - the top of the pre-Mesozoic base; zone of abnormal low values of velocities of primary elastic waves; oil and gas content is possible at account of lateral migration out of deep series of the sedimentary cover of the Lower Kura depression;

7. growth of thickness of the Mesozoic complex 1.5 times as compared with those in the NE slope in the Lesser Caucasus.


Taking into account a unique character of the Saatly ultradeep well SG-1 and its special importance for the fundamental geologic-geophysical studies Geology Institute of Azerbaijan National Academy of Sciences since the 90s of the past century has been taking certain measures to create a stationary geophysical observatory of the International Status on the base of SG-1. Main objective of the observatory will be long monitoring of the state of geodynamic activity of the Earth interior and its prediction.