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RECENT GEODYNAMICS AND EVALUATION OF GEODYNAMIC RISK AT
USE OF SUBSOIL RESOURCES.
by
Yu. O. Kuzmin
Head of Recent Geodinamic Laboratory, United Institute
of Physics of the Earth, Russian Academy of Sciences,
Professor of Moscow State Mining University
Economic News Agency
Moscow
1999
CONTENTS
Introduction.
Chapter 1. RECENT GEODYNAMICS OF SUBSOIL
1.1. Definition of the subject and method of research into recent
geodynamics of subsoil .
1.2. Spatiotemporal structure of recent geodynamics processes
in fault zones.
1.3. Phenomenon of recent superintensive deformation (SD) processes
in fault non-seismic zones.
1.4. Mathematical modeling of recent SD processes in fault zones.
Chapter 2. RECENT ANOMALOUS GEODYNAMICS OF SUBSOIL IN OIL AND
GAS REGIONS
2.1. Deformation and seismic processes inducted by development
of oil and gas deposits..
2.2. Evaluation of effect of recent anomalous geodynamics of
subsoil on objects of oil and gas complex.
Chapter 3.GEODYNAMICS RISK AS TO HIGHLY IMPORTANT AND ENVIRONMENTALLY
DANGEROUS OBJECTS
3.1. Recent geodynamics of faults and problem of safe functioning
of nuclear power plants..
3.2. Problem of geodynamics safety of underground and other
industrial and civil construction objects in developed regions
and megalopolises.
Chapter 4. RECENT ANOMALOUS SUBSOIL GEODYNAMICS - A NEW FACTOR
OF SOCIAL, ECONOMIC, ENVIRONMENTAL, AND INSURANCE RISK
4.1. Evaluation of geodynamics danger and geodynamics risk at
use of subsoil.
4.2. Methods for monitoring over the SD processes for determination
of level of geodynamics risk as to subsoil use objects. 174
Conclusion.
References
CONCLUSION
Currently, in the mark of the century and the millenium, a
radical change is taking place in views on the role of geodynamics
factor for evaluation of environmental, social, economic, and
insurance risk which arises throughout exploitation of environmentally
dangerous objects and objects of special importance. Conducted
research provides conclusive evidence that most dangerous for
a man and his environment are recent (currently happening) deformation
processes developing in fault zones.
As a result of complex generalization of significant amount
of data about recent movements of crust, which was received
on specially organized geodynamics polygons for different purposes,
principally new data about recent geodynamics condition of subsoil
was received. Since such polygons were located in seismically
active as well as in not seismically active regions and were
equipped with identical measuring systems, it proved possible
to conduct a consecutive comparison of basic characteristics
of deformation processes which were received in such different
(from traditional geodynamics point of view) regions.
As a result of the comparative analysis there was discovered
a new class of tectonic movements - recent super-intensive deformations
(SD) of crust in fault zones. In this case most paradoxical
and unexpected result is that the highest intensity of anomalous
deformations can be seen in platform fault zones of seismically
low regions. Such anomalous deformation processes are highly
amplitude (over 50 mm per year or about 10-4÷10-5 per
year), happen in short periods of time (from first months to
first years), located in space and time (from first hundreds
of meters to first kilometers), and have pulsing and/or alternating
directivity.
To study the effect of higher deformation activity of non-seismic
faults compared to seismically active ones, the results of comparison
of seismic and deformation energy characteristics were analyzed
(linear power density of implemented potential energy along
the strike of regional geodetic section which begins in Copetdag's
foothills and ends on the South hillside of Turanskaya platform).
It appeared that the further it got from mountains to platform
(from seismically active zone to non-seismic zone), the SD intensity
rapidly increased, and seismicity fell and fully disappeared
in the platform part. Analogous antiphase behavior of deformation
and seismic processes can also be seen within a single fault
zone. Thus, as a results of the researches conducted in Kamchatka
and Kopetdagsky seismically active regions show, in a period
of lower seismic activity a rapid gaining of the SD processes
in fault zone is established, and contrariwise. Quantitative
results show that stored reserve of potential energy is implemented
in a fault zone in two forms: seismicity and SD. In this case,
a joint irradiation equivalent exists which is general for both
forms of implementation. Thus, it can be presumed that existence
of more powerful deformation processes in non-seismic faults
of platform zones is a result of absence thereat of dissipation
seismic factor, which in seismically active faults provides
a "flow" of part of joint irradiation equivalent in
seismic form, by that decreasing that part of potential energy
which is implemented in the SD form. Considering the fact that
joint potential energy of the medium under deformation consists
of two components - bulk and wave, an anti-phase behavior of
deformation (bulk component) and seismic (wave component) processes,
as well as presence of joint irradiation equivalent, all become
clear.
Analysis of spatio-temporal peculiarities of forming of SD
anomalies made plain the presence of wave deformation processes
in fault zones. These waves were registered in a form of chain
occurrence of SD impulses in abutting faults (from one fault
to the other and so on) or in abutting fragments within one
and the same fault zone.
Processes studied were of a nature of a "relay-race transfer"
of anomalous activity from one activated object to the other.
Eventually, SD processes agitation wave spreads through the
field, while fault zones being the elements which are agitated.
Speed of transfer of deformation agitation from one fault to
the other (inter-fault wave) was from 3 km per year to 30 km
per year, while at the migration of the processes within a single
fault zone (inter-fault wave) speed changed in diapason of 30ё60
km per year. Moreover, such speeds are typical for different
regions (Pripyatskaya cavity, Tersko-Caspian bend, Predkopetdagsky
bend, etc.).
The received empirical generalizations show that the origin
of SD anomalies must be the processes occurring inside these
fault zones themselves. Such statement appears to be fair because
currently well-known models of abyssal geodynamics cannot explain
a monitored spatio-temporal spectrum of recent movements of
crust and especially appearance of SD anomalies in platform
fault zones.
In this respect, author has proposed a new mechanism of derivation
of anomalous deformations in fault zones. Within the limits
of this mechanism formation of SD processes is not directly
called by time code of a regional (external with respect to
volume environment controlled by observing system) stress field,
but is conditioned by changes in parameters (hardness modules,
friction factor, etc.) of originally loaded environment within
fault zones themselves. Arising thereat, SD anomalies are considered
as parametrical, because according to theory of mechanical oscillation,
overbalance by any system from equilibrium condition (system
overbalance) can be reached by two ways: either by an outside
collision force or as a result of change of inside parameters
of the system itself. Generally, physical nature of occurrence
of parametric deformations is seen as follows. Geological environment
is in external and internal (endogenous and exogenous), quasi-static
(global and regional stress fields) and dynamic (water heights,
rippling of Earth orbit, processes of preparation of earthquakes,
seismic waves, technogenic processes, etc.) loads. Moreover,
dynamically active and chemically aggressive fluid system is
constantly presented and redistributed in fault zones, especially
in sedimentary reservoirs. Interaction and cooperative influence
of all these factors are actualized in first place by improved
concentration of environment defects, i. e., in fault zones
with not stable mechanical characteristics, by short-term fluctuations
of rigidity characteristics of formations in local volumes,
which leads to occurrence of SD processes.
Conducted researches show that SD anomalies arise, as a rule,
under influence of minor impacts. So, for example, agitation
of SD processes by atmospheric condensation was elicited, creation
of deformations a the level of 10-5 fault zone, which are conditioned
by preparation of an earthquake which occurred 100 km from the
vantage-ground, initiation of anomalous deformations of low
seismicity, etc.
Thus, discovered SD processes in fault zones represent new class
of tectonic movements - recent parametrically induced movements
of crust in fault zones.
Developed concepts of the mechanism of generation of SD processes
allowed to formulate quantitative model of formation of local
deformations of anomalies in fault zones. It represents semi-infinite
solid which has impurity (inhomogenity) with mechanical characteristics
other then host medium, the edges of which have preset constant
voltages. In this case, during changes in time of mechanical
characteristics inside impurity (parametric induction by small
exposure) and existence of intensive constant voltages at the
edges, takes place the formation of locally deflected mode of
body area in the neighborhood of given inhomogenity (model analogue
of fault zone).
Created within the limits of given approach analytical and
directional numerical models, connecting SD characteristics,
monitored on crust, with parameters of the origins in depth,
allowed to evaluate allocation of anomalous voltages and deformations
throughout depth and to determine the location of the origins
of anomalies (areas of exceeded fissuring) inside fault zones.
On the basis of developed technology for solving inverse problems
of recent faults geodynamics, depth diapasons, sizes, form,
and degree of softering of areas of formation of SD anomalies
were determined. Current analysis of these results with geodynamic
and geological and geophysics situation of regions under examination
showed that the origins of SD processes occur in depth diapason
from first tens of meters to first kilometers, have (in cross
section) form of long (0.05÷0.5 km), vertically oriented
rectangles, timed to zones of bedding of fluid saturated, fissuring
limestone. It appeared that to form anomalous deformations of
crust at the level 10-4÷10-5 it is necessary to have
relative elasticity change of solid block in diapason 1÷3
up to 10÷30 percent, with given at the edge volumes 10
MPa to 100 MPa.
On the basis of concepts of parametrical induction of SD processes,
it was possible to prove autowave nature of spatio-temporal
migration of SD anomalies in fault zones. It appeared that the
monitored speed diapasons and character of the transfer of deformation
activity must be described by nonlinear diffusion equation of
crust displacement, analogues to Kolmogorov-Piskunov-Petrovsky
equation.
The discovered SD processes in fault zones, development of
methods of complex interpretation of observations and diagnosis
of recent deflected mode of fault zones allowed to successfully
state and solve a number of important practical problems, the
most important of which are:
1) quantitative model of processes for earthquakes' preparation
for conditions of young sediment basins was developed and necessity
to conduct the recording of "self" dynamics of faults
at evaluation of the size of the areas of formation of deformation
prognostics was made plain. Effect of parametrical amplifying
of deformation prognostics in fault zones (parametrical prognostics
of earthquakes) was discovered and differential method for geodesic
monitoring in fault zones of seismically active regions was
proposed. Empiric materials were received and model was defined,
demonstrating the dominating role of recent geodynamics of faults
to anomalous behavior of Caspian sea level;
2) stable interaction between variations in oil well debits
and SD processes was elicited. It was showed that SD anomalies
can lead to change in debits at percent 10÷30 level.
It was shown on example of a number of deposits that space contemporaneity
of emergency situations at wells and pipeline systems to fault
zones finds its natural explanation within the concepts of existence
of SD processes in such zones. A method for SD-dangerous zoning
and eliciting of critical depth diapasons within the limits
of which snapping and curving of wells of various technological
purposes, was developed;
3) a method for SD risk evaluation of highly important and
environmentally harmful objects (nuclear power plants and hydrocarbon
deposits) was developed, which is based on the author's definition
of risk, i. e., risk is a mathematical expectation of damages.
Taking as example anomalous deformation of the Moscow Underground
tunnels, necessity for the obligatory recording of SD risk in
megalopolises and generally through construction of civil engineering
and industrial objects was shown;
4) discovered existence of SD processes in platform fault zones
reverses the concept of environmental risk level because precisely
platform regions represent predominant environment. In this
case, new class of environmental risk appears - ecological and
geodynamics risk in two forms: direct (toxic fluids emission
from activated faults) and indirect (SD influence on accident
rate of objects which are environmentally dangerous for man
and his environment). Essentiality of recording of ecological
and geodynamics risk for solving such global environmental problem
as greenhouse effect was motivated.
The results presented demonstrate that recent geodynamics of
faults and especially their most extreme exhibition in the SD
processes form, must become an object of intent consideration
in all spheres of human activity. Recording of SD factor should
be conducted in normative acts issued by state agencies, regulating
safe exploitation of most important and environmentally dangerous
objects (nuclear power plants, waterpower plants, main oil and
gas pipelines, large hydrocarbon deposits and their infrastructure,
places of nuclear and toxic waste disposal, etc.). To improve
social protection of population from SD danger, preparation
of new approaches and norms for SD risk insurance is required.
All that definitely must be reflected in amendments and additions
to applicable law in part related to SD-danger recording.
The aforesaid states the requirement for conducting thorough
diagnostics of the level and scale of SD and danger of SD risk.
Also, the following must be considered. Constant technogenic
loading of subsoil together with active natural processes creates
geoenvironments in fault zone areas of constitutive fluctuation
of natural deformation regime. It is well known that concepts
of the nature of cause-effect relations change in principle
in fluctuation systems. If in fluctuation systems the measures
of cause and effect are always of the same order, then small
reasons lead to quite big consequences in fluctuation and constitutive
nonlinear systems. In these systems, fluctuation itself must
be treated as cause of events. In such situation it is essential
to conduct very thoughtful system of diagnostics of crust fields
with fluctuation deformation characteristics (SD zoning). For
that purpose follow-up realization of three interconnected procedures
must be conducted:
1) detailed and measurement-assured monitoring of SD processes;
2) complex several-variant interpretation of results of the
monitoring and selection of different scenarios of possible
negative contour (evaluation of SD danger);
3) determination of the level of SD risk, forecasting environmental,
social and economic consequences, and formulating strategies
for preventive arrangements.
In author's opinion, it is precisely today, at turn of centuries
and milleniums, when feeling entrenches that whole life on Earth
is organic, local changes in one place can create danger to
the remaining parts of world, and that we are responsible for
life order on our planet. Now it becomes possible to understand
not only with common sense, but with heart as well, the distance,
frightening at beginning, where natural science and technology
are calling us. The Little Prince, who is concerned about our
planet, speaks precisely about this, exclaiming: "Really
one can see with his heart, the most important things are invisible!"
In that case, only a harmonized coexistence of Nature and Man
is possible. Only that is how author sees the main strategy
of rational nature management.
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