Geodynamic Monitoring System for Needs of Safe Prospecting Works and Extraction of Oil and Gas in large Regions
Prospecting on and extraction of oil and gas from deep set layers are endangered by technologic and environmental risks that may cause large scale disruption of the complicated and expensive industry.
Risks of catastrophes are multiplied in case when works are connected with oil (gas) fields at the sea or ocean bottom.
Besides technological factors especially dangerous ones are geodynamic processes that control fast (in real time) variations of stress-strain field and changes vertical and horizontal movements of geological formations.
The global stress field is very sensitive to strong disturbances of its state in any spots of the Earth that can be registered as micro-strains by specially developed methods and technologies.
The strongest geodynamic events are able change state of geological massifs at far and very far (thousands of km) distances from the source of disturbance, rearrange the structure of stress-strain field in areas over millions sq. km.
Such peculiarities of the stress field were revealed as a result of direct a multiyear observation that was registered as a discovery of the new type of geophysical field – Hydro-Geo-Deformation (HGD) field of the Earth (The Vartanyan – Koulikov hydrogeological effect, 1982, Diploma #273).
The formula of discovery states: There were disclosed globally spread fast pulsating changes in hydrogeosphere as a result of ability of latter to react on stress state variations in lithosphere.
It becomes evident that in case of critical geodynamic changes in lithosphere all the objects of human activity inevitably are involved in sphere of risk. The level of danger for particular area, object, or construction is possible to evaluate following the geodynamic monitoring results of geological environment.
Geodynamic monitoring procedure is based on information of the HGD field of the Earth and includes systematic observation of geological massifs tiny state changes. The HGD field reflects all the smallest fluctuations of the stress-strain field that develop in scale of real time in rock massifs. That kind of evolutions characterizes appearance and disruption of short-term living structures of deformation that can endanger any particular area. The accuracy of measurements level is very high [up to d ()].
Information on tempo and intensity of deformation and images of subsequent deformogramms are used for revealing and mapping of dynamic-dangerous zones. In cases of fast developing processes of the massif disruption this information becomes critical to stop the functioning of endangered object or even evacuate personal (population).
Despite of the very high level of contemporary drilling technologies, reliable technical means to prevent outburst of oil wells etc, the factor of geodynamic danger always persists.
The strategy of safe prospecting works on oil and gas fields requires inclusion into the cycle of enterprise the global (sub-global) strain field monitoring system to evaluate the level of geodynamic danger existing in the region under study.
If not to say about the global (sub-global) scales the proper geodynamic monitoring system could be of urgent necessity to protect prospecting works in the scale of region.
Speaking about the catastrophe April 21 2010 with the platform Deepwater Horizon and comparing of it’s time appearance with other misfortunes it is necessary to stress down the following:
· During the first 4 months of 2010 there were registered six strong geodynamic events – devastating earthquake in Haiti (12.01.2010, M7.0), catastrophic earthquake in Chili (27.02.2010, M8.8), earthquake in China (14.04.2010, M6.9), earthquake in Chili (01.05.2010, M5.9), earthquake in Chili (03.05.2010, M6.4), the volcano Eiafyallaecul eruption (20.03.2010) that characterize sharp activating of geodynamic forces all over the world. It needs to stress down that two of that six geodynamic events happened in the basin of the Atlantic. And one of them was in the area of the Mexican golf.
· Position of the Deepwater Horizon platform during the catastrophe gives the background to assume that geological massifs of that part of Mexican golf did not relax following discharge of elastic energy after the Haiti earthquake and continue undergo anomalous geodynamic stresses. If it’s so it will be right to assume that the Deepwater Horizon’s catastrophe had the natural-technological origin.
· Based on HGD monitoring experience in different parts of the World the following assumption may be put forward: strong expanding deformations are developing nowadays in rock massifs of region under consideration and it means that new seismic tremors are not excluded in the nearest future in that area.
· It’s understood that the above mentioned statement can be distinguished by someone as not having sufficient base of proves or even can be taken as a mere speculative one. At the same time it is necessary to stress down that having had the geodeformation monitoring data as well as corresponding data characterizing the strain field of particular geologic object any qualified expert would be able to evaluate the level of stress state of the environment and possible interrelations between “technological reasons” of catastrophe and geodynamic development tendencies in region.
More over of that, having had this kind of information one could be able to evaluate the level of geodynamic danger and to issue prediction or even warning forecast in order to terminate any kind of activity in taken area.
To finalize this short note it’s necessary to stress down the following:
1. The geodynamic monitoring network in any taken region gives possibility to have permanent stream of information about stress-strain state of vast area and to get all kind of parameters characterizing critical situation of particular geological objects.
2. The information about current geodynamic processes gives sufficient time lag to undertake necessary actions to change the regime of prospecting works or terminate extraction of product.
3. This kind of information can become the base to choose the best regime of prospecting works or of oil (gas) extraction.
To illustrate the intensity and speed of strain field changes in scale of real time some results of HGD monitoring during the Spitak earthquake are given below. The monitoring area is over 500 000 sq. km.
Caucasus, Armenia. Destructive Spitak earthquake (M6.9, 07.12.1988, 10:41 Moscow time or 07:41 GMT)
The computerized reconstructions of HGD field state prior the main shock; in the moment of earthquake; 1 hour and 19 minutes after the main shock.
Comparison of these maps (images) presents scale of sharp changes in state of the regional strain-field, which were registered on the specialized HGD monitoring network. The monitoring area exceeds 500 000 sq. km.
Red spots represent short-term living structures of expansion;
Blue and dark blue spots – short-term living structures of compaction;
Blue stars – epicenters (main shock).
HGD field state prior, during and after the Spitak earthquake:
07.12.1988:10 (41 minutes prior the main shock);
07.12.1988:1041 (main shock);
07.12.1988:12 (1 hour 19 minutes after the main shock).