Leonid F. Khilyuk

Electrobioremediation of soils contaminated with hydrocarbons and metals: progress report

Restoration of soils contaminated with hydrocarbons and metals is one of the most important problems of environmental protection. During the last 30 years, considerable progress has been made in the development of effective remediation technologies. Modern purging technologies are based on the chemical and biological degradation of contaminants and their conversion to safe forms or to intermediate substances convenient for transport in soils. To accelerate transport of contaminants or their intermediate substances in soils, electrical fields (direct current) are applied to zones being remediated. This allows the volumetric rate of transport to increase ≈ 50-60 times, and the substances to collect at convenient removal sites Fundamental experiments were performed by a group of researchers at the University of Southern California in the early sixties. The experiments involved application of direct electrical current for acceleration of the flow of solutions in soils. This, together with the latest advances ...

Global warming: Are we confusing cause and effect?

The writers show that the present-day global warming is not due to the increase in the volume of greenhouse gases, but rather to the increased solar activity. It appears that we are at the rising phase of the latest 80–90 year cycle of the solar activity. At the present time, there is no sound justification for the cut in the man-induced carbon dioxide emission as required by the Kyoto Protocol of 1997. The rising global temperature drives large volumes of CO2 from the ocean water into the atmosphere. Thus “cause” and “effect” of global warming phenomenon are misunderstood by many scientists.

Numerical criterion and sensitivity analysis for time-dependent formation pressure in a sealed layer

Abstract Methodology and results of analysis of variation in time of a mean value of abnormal component of the formation pressure in a layered medium and its sensitivity analysis are presented. The abnormal component is defined as the difference between the actual and hydrostatic formation pressure. The model used by the writers is a combination of two layers of finite thickness. The upper layer is a seal (caprock) with low porosity and low permeability, whereas the lower layer has higher porosity and higher permeability. The methodology is based on the assumption that the process of sedimentation (accumulation of sediments) causes rock compaction, which in turn leads to increased flow of fluids from the underlying formations (shales, etc.) into the permeable layer. A single integral parameter is developed the values of which discriminate one of the three possible scenarios: formation pressure development, increased in time, remained unchanged, or decreased in time. Simple structure of the model allowed to obtain analytical expressions for sensitivity coefficients of the formation pressure and identify parameters of the medium to which characteristics of the formation pressure are most sensitive.

CHAPTER 16 – Typical Composition of Natural Gases

Natural gas consists of at least 95% hydrocarbons belonging to the paraffin series. The remainder are nonhydrocarbon gases, such as nitrogen, carbon dioxide, and, sometimes, small quantities of hydrogen sulfide. The presence of sulfur compounds, such as mercaptans and hydrogen sulfide, are responsible for odors sometimes associated with natural gases. In some areas, such as Texas, helium may also be present. Carbon dioxide and hydrogen sulfide are referred to as acid gases as they can form acids on contacting water. Gases such as nitrogen and helium are referred to as inert gases. Natural gas may be partially or completely saturated with water vapor, and is a colorless, odorless mixture unless sulfur is present. The principal hydrocarbons present in natural gas are methane, followed by ethane, propane, butanes, and heavier components. Upon migration, heavier hydrocarbons are preferentially adsorbed on rock minerals, mainly clays. The composition of natural gases produced from an oil reservoir will vary with various operating oil/gas separator pressures.

Pronounced changes of upward natural gas migration as precursors of major seismic events

Pronounced changes in the rate of natural gas migration to the surface of the Earth in the vicinity of faults and fractured zones can be used as precursors of major seismic events. The authors propose to use them in conjunction with other integral parameters characterizing the energetic state of a tectonic system for the development of a multicomponent earthquake prediction technique. Thus, it is necessary to develop and implement a stationary natural gas mobility monitoring system covering the vicinity of major faults and fractured zones at the area of interest.

CHAPTER 15 – Gas Migration

The chapter discusses gas migration, which can occur in the earths crust as either a continuous or discontinuous phase through porous, water-filled media to the surface. The direction of gas migration in water-saturated formations is generally vertical as the primary force moving the gas is the difference between the specific weights of gas and water (buoyancy). Sources of gases include low-temperature bacterial fermentation, thermogenic breakdown of deeply buried sedimentary organic matter, and the mantle. For biogenic and thermogenic decomposition of organic materials, almost all of the hydrocarbon gases are composed of methane with very few heavier hydrocarbons. Thermogenic decomposition of organic material may give rise to oil and gas under high temperature and pressure. The origins of biogenic and thermogenic gases can be determined by isotopic gas analysis. The chapter also discusses nonhydrocarbon gases and mixing of gases.

Cooling of Atmosphere Due to CO2 Emission

Abstract The writers investigated the effect of CO2 emission on the temperature of atmosphere. Computations based on the adiabatic theory of greenhouse effect show that increasing CO2 concentration in the atmosphere results in cooling rather than warming of the Earths atmosphere.

Differential sensitivity analysis and multi-variant simulation of formation pressure and temperature in heterogeneous media

Abstract Methodology of differential sensitivity analysis and sensitivity-based aggregate simulation for formation pressure, temperature and fluid flow is developed here. It is aimed at estimation of variations of formation pressure, temperature and velocity field for fluid flow due to variations in the properties of the medium and fluids in the pores. It includes the use of the so-called “sensitivity functions” defined as partial derivatives of the formation pressure and temperature with respect to parameters of the rock and fluids in the pores. It is shown that the sensitivity functions are defined by the same system of equations as formation pressure and temperature fields with the right-hand side of the equations dependent on the type of sensitivity function. There are several important applications of the differential sensitivity analysis and sensitivity functions: (1) Sensitivity functions allow to estimate, under certain conditions, the magnitude of variation of formation pressure and temperature fields 1 (2) Using sensitivity function-based technique, it is possible to partially decouple the system of equations for formation pressure and temperature fields under conditions of slow variations of temperature or pressure in time. (3) Differential sensitivity analysis may serve as a basis for calculation of multiple versions (aggregate simulation) of formation pressure and temperature fields due to various changes in the parameters of the medium and pore fluids.

CHAPTER 11 – Messages from the Earth's Crust

This chapter focuses on searching for an appropriate precursory phenomena and revealing the patterns of premonitory events related to these phenomena, which are the primary considerations in developing earthquake prediction techniques. Success in short-term earthquake prediction depends on whether a chosen precursory phenomenon can indicate the time and place of a major rupture. Patterns for monitoring points are heterogeneous tectonic area and homogeneous tectonic fault. The increased unbalanced crustal stresses can move crustal blocks in arbitrary directions that can be manifested in the changes of tilts. GPS (Global Positioning System) provides a convenient means for measuring land surface subsidence, and consists of a set of orbiting satellites that continuously transmit radio signals. There is some evidence that electrical rock properties change when the stresses applied to the rock are altered. There are two phenomena of interest: changes in the electrical resistivity as a result of the rock stress alteration and generation of electrical fields by piezoelectric effect. The VAN method uses seismic electric signals (SES) as short-term precursors of earthquakes. Wave velocity ratio is also discussed in this chapter.

CHAPTER 21 – Interrelationships among Subsidence, Gas Migration, and Seismic Activity

The chapter deals with changing rates of gas migration to the earths surface, which may signal the development of ground subsidence. Subsidence often occurs due to mans need for fresh water; and oil and gas to satisfy domestic, industrial, and agricultural demands. Withdrawal of the fluids from a petroleum reservoir or an aquifer reduces the pore pressure and results in the increase in effective stress. Thus, compaction of reservoir rocks occurs and to balance the existing overburden pressure, the overlying formations and the land surface subside. The primary cause of subsidence is rock compaction. Compaction is the result of several simultaneously acting phenomena that are induced by the increase of effective stress in the rocks in which the pore-pressure is reduced due to fluid withdrawal. Presence of shale and clay beds within the productive zone can significantly contribute to the overall reservoir compaction. Compaction takes place over a long period of time because the process involves the slow expulsion of water. Shallow reservoirs will undergo viscous creep, deforming horizontally as well as vertically if the overburden pressure is principally supported by the grain-to-grain stress over a long period of time. Subsiding bowl develops slowly, over a very large area with structures inclining toward the center of the subsiding bowl and fractures developing at the periphery.