During the past 50 years, quartz dissolution kinetics and solubility measurements have been the subject of numerous investigations. Researchers have been motivated either because of their interest in understanding important natural geologic processes in the earth or because of a need to quantify dissolution rates for chemical processes above ground or for geothermal heat extraction underground....

Tracers provide an important means of interrogating the subsurface to provide critical information about hydraulic characteristics of the reservoir. In a geothermal reservoir, reactive tracers may add information about the thermal state of the reservoir. Tracer test analysis methods vary, but generally involve curve fitting to a simple model of the system or a moment analysis approach. The Idah...

Introduction That a “high temperature reservoir” (HTR) underlies a “typical” vapor-dominated reservoir under certain circumstances is well known (Drenick, 1986; Pruess et al., 1987; Walters et al., 1988). However, formation and behavior of such a feature is poorly understood. Recent theories regarding the behavior of the HTR fall into one of two broad categories: transient and steady state. In ...

Numerically inverting simultaneous pressureinterference measurements from multiple observation wells can help to establish the large-scale spatial distributions of permeability and storage within a geothermal reservoir. For realistic results, it is important to incorporate double-porosity (MINC) descriptions into the modeling process to properly reproduce the short-term pressure-transient respo...

Transient heat andor fluid mass exchange between the permeable fracture system and the surrounding relatively impermeable country rock can be treated in geothermal reservoir simulators using the “MINC” technique. This approach typically requires about an order of magnitude more computer time than the analogous “porous medium” problem. Under practical conditions, the problem can often be lineari...

A numerical method as well as a theoretical study of non-Darcy fluid flow through porous and fractured reservoirs is described. The non-Darcy behavior is handled in a three-dimensional, multiphase flow reservoir simulator, while the model formulation incorporates the Forchheimer equation for describing single-phase or multiphase non-Darcy flow and displacement. The non-Darcy flow through a frac...

The transport of chemicals or heat in fractured reservoirs is strongly affected by the fracture-matrix interfacial area. In a vapor-dominated geothermal reservoir, this area can be estimated by inert gas tracer tests, where gas diffusion between the fracture and matrix causes the tracer breakthrough curve (BTC) to have a long tail determined by the interfacial area. For water-saturated conditio...

Inferences have to be made about likely structures and their effects on fluid flow in a geothermal reservoir at the pre-drilling stage. Simple mechanical modelling, using reasonable ranges of values for rock properties, stresses pressures, is used here predict range possible that are exist sub-surface may generated during stimulation potential reservoir. In particular, Mohr diagrams show under ...

Cuttings from geothermal wells in Dixie Valley, Nevada document the complex history of the Jurassic reservoir rocks now contained within the hanging wall of the Stillwater normal fault. Six stages of postOligocene alteration can be recognized on the basis of mineral paragenesis, rock associations, fluid-inclusion temperatures and apparent salinities. The paragenetic sequence from oldest to youn...

NEDO has developed MEPAS, a software for exploration of geothermal reservoir. MEPAS has bcen developed as a tool for geologists to analyze earthquakes and find fractures by comparing earthquakes with other exploration data. MEPAS consists of a seismic data processing part and a geological analysis part. The geological analysis part features 3D display, time and space distribution display, fract...