In efforts to increase and extend production from oil and gas fields, as well as to keep wells operational, petroleum engineers pump a wide variety of fluids into the subsurface. In this chapter we consider how multicomponent chemical reaction analysis can be used to foresee unfavorable consequences of reservoir flooding. We take up two examples, sulfate scaling in North Sea oil fields and the alkali flooding of a hypothetical clastic reservoir.

Many redox reactions in the natural environment proceed too slowly to approach their equilibrium state, absent the action of catalysts or enzymes. In this chapter, we consider how to trace multicomponent reaction paths in which the progress of redox reactions is described by kinetic rate laws. We frame our discussion in terms of three example calculations. In the first example, ferrous iron both catalyzes and provides reducing power to convert uranyl to insoluble uranium hydroxide. The autocatalysis of manganese, in which the reaction product operates as the catalyst that promotes the reaction, serves as the second example, and the microbial degradation of phenol makes up the final illustration of the method.

The objective of groundwater geothermometry is to use a groundwater’s chemistry to estimate the temperature at which it was last in equilibrium with its environment, to better understand the water’s origins. In this chapter, we explore the use of multicomponent chemical reaction modeling as a tool in geothermometry. We first construct a synthetic example to illustrate the calculation process. We then apply the modeling to better understand the chemistry of a hot spring in Iceland as well as geothermal water from that country.

We incorporate in this chapter kinetic rate laws into reactive transport models to show how water–rock interaction leads to chemical weathering. We consider as examples rainwater infiltrating an orthoquartzite aquifer and the percolation of rainwater through a mineralogically complex soil, accounting for biogenic production of carbon dioxide.

Increasingly since the 1930s, various industries around the world that generate large volumes of liquid byproducts have disposed of their wastes by injecting them into the subsurface of sedimentary basins. In this chapter, we provide two examples of how the application of multicomponent chemical reaction modeling could have prevented catastrophic well failures in Illinois, USA. The first example involves the reaction of a caustic waste stream with the confining layers in a dolomitic accepting formation. In the second example, injection of an acidic waste stream into dolomite resulted in repeated well blowouts.

Multicomponent chemical reaction analysis constitutes a powerful tool for understanding the origin and provenance of evaporated surface waters, as well as the mineralogy of evaporite deposits. In this chapter, we apply such modeling to better understand the springs and saline lakes of the Sierra Nevada Mountains in the USA. We then develop quantitative models of the reaction accompanying the evaporation of seawater to the point of nearly complete desiccation, assuming reaction occurs in both closed and open systems.

Acid drainage is a persistent environmental problem in many mineralized areas. The drainage results from weathering of sulfide minerals that oxidize to produce hydrogen ions and contribute dissolved metals to solution, posing a considerable threat to the environment. In this chapter we construct geochemical models to consider how the availability of atmospheric oxygen and the buffering of host rocks affect the pH and composition of acid drainage. We then look at processes that can attenuate the dissolved metal content of drainage waters.

Geochemists increasingly find a need to better understand the distribution of microbial life within the geosphere, and the interaction of the communities of microbes there with the fluids and minerals they contact. How do geochemical conditions determine where microbial communities develop, and what groups of microbes they contain? And how do those communities affect the geochemistry of their environments? In this chapter we use multicomponent chemical reaction modeling combined with thermodynamically consistent kinetic expressions to explore how microbially catalyzed reactions proceed in the laboratory and in nature.

Diagenesis is the set of processes by which sediments evolve after they are deposited and begin to be buried. In this chapter we consider how multicomponent chemical reaction modeling applied to open systems might be used to study the nature of diagenetic alteration. We take as examples the origin of dolomite cement in the Gippsland basin of Australia and the development of anhydrite and dolomite cements in the Denver basin, USA.

In this chapter we construct multicomponent chemical reaction models of how an aqueous fluid might react with the minerals it contacts, according to kinetic rate laws. We show that the fluid can be in equilibrium or disequilibrium with respect to the minerals, and how the fluid chemistry can approach an apparent equilibrium that is in fact a steady state, rather than a thermodynamic equilibrium. We further construct example calculations that demonstrate the basis of Ostwald’s step rule and the nature of the incongruent dissolution of albite feldspar.

We construct in this chapter reactive transport models of the mobility of heavy metals in an aquifer containing a complexing surface. The modeling shows that surface complexation can play a controlling role in the fate and transport of heavy metal contamination in the environment. Surface complexation causes not only retardation, as might be expected from simple sorption theory, but a pronounced tailing that hinders remediation by pump-and-treat methods.