Zora V. Dash

FEHMN 1.0: Finite element heat and mass transfer code

A computer code is described which can simulate non-isothermal multiphase multicomponent flow in porous media. It is applicable to natural-state studies of geothermal systems and ground-water flow. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved using the finite element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat and mass transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. A summary of the equations in the model and the numerical solution procedure are provided in this report. A user`s guide and sample problems are also included. The main use of FEHMN will be to assist in the understanding of flow fields in the saturated zone below the proposed Yucca Mountain Repository. 33 refs., 27 figs., 12 tabs.

User`s manual for the FEHM application -- A finite-element heat- and mass-transfer code

The use of this code is applicable to natural-state studies of geothermal systems and groundwater flow. A primary use of the FEHM application will be to assist in the understanding of flow fields and mass transport in the saturated and unsaturated zones below the proposed Yucca Mountain nuclear waste repository in Nevada. The equations of heat and mass transfer for multiphase flow in porous and permeable media are solved in the FEHM application by using the finite-element method. The permeability and porosity of the medium are allowed to depend on pressure and temperature. The code also has provisions for movable air and water phases and noncoupled tracers; that is, tracer solutions that do not affect the heat- and mass-transfer solutions. The tracers can be passive or reactive. The code can simulate two-dimensional, two-dimensional radial, or three-dimensional geometries. In fact, FEHM is capable of describing flow that is dominated in many areas by fracture and fault flow, including the inherently three-dimensional flow that results from permeation to and from faults and fractures. The code can handle coupled heat and mass-transfer effects, such as boiling, dryout, and condensation that can occur in the near-field region surrounding the potential repository and the natural convection that occurs through Yucca Mountain due to seasonal temperature changes. This report outlines the uses and capabilities of the FEHM application, initialization of code variables, restart procedures, and error processing. The report describes all the data files, the input data, including individual input records or parameters, and the various output files. The system interface is described, including the software environment and installation instructions.

Convolution-based particle tracking method for transient flow

A convolution-based particle tracking (CBPT) method was recently developed for calculating solute concentrations (Robinson et al., Comput Geosci 14(4): 779–792, 2010). This method is highly efficient but limited to steady-state flow conditions. Here, we present an extension of this method to transient flow conditions. This extension requires a single-particle tracking process model run, with a pulse of particles introduced at a sequence of times for each source location. The number and interval of particle releases depends upon the transients in the flow. Numerical convolution of particle paths obtained at each release time and location with a time-varying source term is performed to yield the shape of the plume. Many factors controlling transport such as variation in source terms, radioactive decay, and in some cases linear processes such as sorption and diffusion into dead-end pores can be simulated in the convolution step for Monte Carlo-based analysis of transport uncertainty. We demonstrate the efficiency of the transient CBPT method, by showing that it requires fewer particles than traditional random walk particle tracking methods to achieve the same levels of accuracy, especially as the source term increases in duration or is uncertain. Since flow calculations under transient conditions are often very expensive, this is a computationally efficient yet accurate method.

Calculation of resident groundwater concentration by post-processing particle-tracking results

A post-processing technique that allows relatively simple random walk particle-tracking results to be extrapolated to transport scenarios of considerably more complexity has traditionally been used to calculate flux at specified monitoring locations. Previous extensions of the post-processing approach to calculate resident groundwater concentrations could not disentangle concentrations of mobile and immobile mass in dual-porosity systems, which limited their utility. A variant of the post-processing method that allows for the calculation of resident concentrations of mobile and immobile mass is introduced and tested. The resulting combination of methods—random walk particle tracking without retention processes followed by post-processing to add the effects of retention—is a powerful and practical strategy for assessing the transport of radionuclides or other contaminants in field-scale applications.

Procedure to Complete EE-2A

This report details the general procedure for testing well EE-2A. Well EE-2A was side-tracked off of a whipstock set at 9,748 ft within section milled in the 9-5/8 in. casing from 9,688 ft. to 9,748 ft. The well was then directionally drilled to 12,360 ft. A number of in-flow zones from well EE-3A have been determined. The shallowest in-flow zones occurs at approximately 10,800 ft.

Experiment 2076 Report

The purpose of Experiment 2076 was to test the well completion in EE-2A by stressing the well to the worst-case conditions. The worst case was considered to be a surface pressure of 5000 psi and thermal stresses corresponding to full cooldown in the well. A secondary objective of this experiment was to provide an initial stimulation of the joints intersecting EE-2A, which had previously been exposed to a maximum of 1500 psi.

Extension of two-layer fracture-systems created in hot dry rock - simulation of exp. 2059 and exp. 2062

At Los Alamos National Laboratory, more than ten hydraulic fracturing experiments have been conducted to stimulate a hot dry rock reservoir. Two hydraulic fracturing attempts, Exp. 2059 and Exp. 2062, successfully established a large fracture system connecting an injection well, EE-3A, and a production well, EE-2. The initial closed loop flow test (ICFT) is planned (from May through June, 1986) to get information on volume impedance and temperature of the reservoir. The fracture systems created by the two experiments show characteristics that are different from each other.

Experiment 2039 – Diagnostic Logging in EE-3

Experiment 2039, diagnostic logging in EE-3, was conducted in two parts. Part A, temperature and collar locator surveys while injecting water was run from ~16:00, 4-Apr-84 through ~11:00, 5-Apr-84. Part B, tracer surveys, run from ~8:15 - 21:00, 6-Apr-84. The purpose of the surveys was to determine fluid entry locations in the open hole sections of EE-3

Procedure for an EE-3 Vent Experiment, Experiment No. 2045

During Experiment 2042 approximately 2 million gallons of water were injected in the EE-3 wellbore. This caused seismic activity from the bottom of the well to a region well above the casing shoe (3900 m TVD to 2800 m TVD). Thus water was injected into both the lower high pressure zone and the upper low pressure zone just below the casing shoe. Later experiments have shown that these two zones are connected. In the past the upper zone has often been considered to be a water loss zone (thief zone).

Experiment 2034. The Evaluation of Heat Transfer in the Foam-Filled EE-3 Annulus

The purpose of Experiment 2034, conducted October 20, 1983, was to measure the heat transfer coefficient in a foam filled annulus. Previous experiments with using nitrogen gas in the annulus resulted in transfer coefficients high enough that heating of the injected water would be required if fracturing were ever to be resumed in EE-3.