Procedures to calculate the viscosities of in situ reservoir gases and liquids from their composition have been developed and evaluated. Given a composition expressed in methane through heptanes-plus, hydrogen sulfide, nitrogen and carbon dioxide together with the molecular weight and specific gravity of the heptanes-plus fraction, the procedures are capable of calculating the viscosity of the gas or liquid at the desired temperature and pressure. The procedure for reservoir liquids was developed using the residual viscosity concept and the theory of corresponding states, and was evaluated by comparing experimental and calculated results for 260 different reservoir oils ranging from black to highly volatile. The average absolute deviation was 16 per cent. This is the first known procedure for calculating the viscosity of reservoir liquids from their compositions as normally available, i.e., including the heptanes-plus fraction. The procedure for reservoir gases uses a sequence of previously published correlations. Evaluation of the procedure was accomplished by comparison of 300 calculated and experimental viscosities for high-pressure gas mixtures in the literature. The average absolute deviation was 4 per cent. The calculations are useful fordetermining viscosities in compositional material balance computations andpredicting the viscosity decrease which occurs when gases, LPG, or carbon dioxide dissolve in reservoir oils. INTRODUCTION Methods to predict viscosities of reservoir fluids from the normally available field-measured variables have been presented. Beal,1 Standing,2 and Chew and Connally3 correlated oil viscosities with temperature, pressure, oil gravity and gas-oil ratio. Carr, Kobayashi, and Burrows4 and Katz et al.5 have presented correlations for reservoir gas viscosities as a function of temperature, pressure and gas gravity. Like all intensive physical properties, viscosity is completely described by the following function:Equation 1 where xi=1. Eq. 1 simply states that viscosity is a function of pressure, temperature and composition. These previous correlations1–5 may be viewed as modifications of Eq. 1, wherein one assumes more simple functions may be used. The assumptions are practical, because the composition is frequently not known. Further, the assumptions are sufficiently valid so that these correlations are frequently used for reservoir engineering computations. In compositional material balance6–9 computations, the compositions of the reservoir gases and oils are known. The calculation of the viscosities of these fluids using this composition information is required for a true and complete compositional material balance. For reservoir gases, Carr, Kobayashi and Burrows4 have presented a suitable compositional correlation. For reservoir oils, no correlation is available, and data from reservoir fluid analyses have been used7–9 for compositional material balance calculations.* From a theoretical point of view, this is entirely invalid. The reservoir fluid analysis, whether flash, differential, or other process, does not duplicate the compositions which occur during the actual reservoir depletion process, therefore the viscosities measured during reservoir fluid analysis are not those which occur in the reservoir. From a practical point of view, the "error" of using viscosities from reservoir fluid analysis is of varying and unknown significance. One can say qualitatively that the error is greatest where compositional effects are greatest, i.e., for volatile oil and gas condensate reservoirs and pressure maintenance operations. The first requirement to obtain a quantitative estimate of the significance of the error is to develop a reliable compositional correlation for the viscosities of reservoir oils. No such correlation has been available. Consistent with this requirement, the objective of this study was to develop a procedure to predict the viscosity of reservoir fluids from their compositions. Normally, the compositions of reservoir fluids are available expressed as mole fractions of hydrogen sulfide, nitrogen, carbon dioxide and the hydrocarbons methane through the heptane-plus fraction, with the average molecular weight and specific gravity of the latter. The final correlation was to use the composition in this form. While the more challenging objective of the study was the development of a correlation for the viscosities of reservoir oils, the viscosities of reservoir gases were also studied.

Project Rulison was designed to use underground nuclear technology to determine the potential of this technique for commercial development of the deep, thick, lenticular, low permeability Mesaverde Formation of the Rulison Field in Garfield County, Colorado. A method of stimulation, far greater in magnitude and efficiency than conventional hydraulic fracturing, is needed to recover this gas at economic rates. The Project Rulison exploratory well, R-EX, was completed in May, 1968. Detailed testing of this well provided data on geology, hydrology and reservoir characteristics. The data obtained from the testing have been used to determine the flow capacity of the Mesaverde reservoir. The reservoir characteristics were then used as input data to make predictions of post-shot reservoir performance in the nuclear stimulated well. A nuclear explosive with a design yield of 40 kilotons was emplaced in a 10-3/4" hole at a depth of 8426' below ground surface and detonated on September 10, 1969. Appraisal of the data taken at shot time indicate that the explosive behaved as predicted. The explosion was completely contained underground as predicted and no major seismic damage occurred. The post-shot drilling program, to re-enter the chimney, and test program, to determine the degree of reservoir stimulation achieved, are discussed. Data taken during the initial phases of the post-shot re-entry and evaluation phase will be given.

Gamma radiation, product of the atomic age, in one aspect of its potential application in the chemical industry T H E . advent of the atomic energy program stimulated many research activities to discover uses for the high-energy radiation made available by the fission products of the nuclear reactors. The use of this radiation as a catalyst in chemical reactions has been shown to be very effective in certain cases (2, 3) and may prove to be advantageous on an industrial scale.I n the absence of fission-product sources and because of the expected use of gamma radiation, the experimental work a t Michigan has been conducted with cobalt-60 sources nominally rated a t 1 and 10 kc. Actual intensity levels during the course of this investigation were about one third the nominal values.I n this study various polymers of butadiene and styrene were produced by gamma radiation. Also polysulfone compounds were obtained by reacting sulfur dioxide and various unsaturated hydrocarbons. The data presented are in most cases not complete for any range of variables. They represent preliminary investigations and are presented to show that radiation does affect the reactions. A more complete study of some phases of this work is being made and will be presented a t a later date. they will safely withstand pressures up to 400 pounds per square inch.The gas-loading rack (schematic diagram) was constructed of heavy borosilicate glass tubing to facilitate loading the vials and was equipped with three loading lines, one of which was used as an emergency vent to the hood. A gasscrubbing column and a gas-drying column, which were incorporated in one of the load lines, could be used to remove the amine inhibitor present in one of the reactant gases used. A cold trap to condense the vapors that might have harmed the vacuum pump was also included in the system. The standard high-vacuum Duo-Seal pump capable of producing a vacuum of less than 100 microns of mercury was used in this work. Dry ice in a 60-40% mixture of chloroform and carbon tetrachloride provided a temperature of -75' C. for the condensing baths in both the cold trap and the cold bath around the vial.Chemicals. Some of the chemicals used in these preliminary experiments were obtained from commercial sources and others were prepared in this laboratory. The analyses and methods of preparation were as follows:1,3-BUTADIENE: Grade A: 0.4% butane and/or butene, 0.5% acetylene, 0.1 yo phenyl-p-naphthylamine inhibitor, 1,2-butadiene also present in unknown amount.Grade B: 99.77y0 1,3-butadiene; normal butane, butenes, and possibly a trace of acetylenes (0.23%). STYRENE: 500 ml. distilled under vacuum from stabilized reagent-grade styrene, rejecting initial 50 ml. and final 150 ml. NACCONAL AND ALCONOX SOLUTIONS :Saturated solutions in distilled water were prepared in the laboratory and used throughout the experiments. OTHER SOAP SOLUTIONS : Solutions of sodium stearate, calcium stearate, zinc stearate, and lead oleate were prepared from reagent grades and used throughout the experiment...

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Project Rulison was designed to use underground nuclear technology to determine the potential of this technique for commercial development of the Mesa-verde formation of the Rulison Field in Garfield County, Colorado. A method of stimulation, far greater in magnitude and efficiency than conventional hydraulic fracturing, is needed to recover the gas at economic rates. Detailed testing of the Project Rulison exploratory well, R-EX, provided data on geology, hydrology and provided data on geology, hydrology and reservoir characteristics. The data obtained from the testing have been used to determine the flow capacity of the Mesaverde reservoir. The reservoir characteristics were then used as input data to make predictions of post-shot reservoir performance in the nuclear stimulated well, using a radial, unsteady state gas flow computer model. The calculations show that rates of production will be sufficient if costs production will be sufficient if costs can be controlled. Costs of nuclear stimulation must be drastically reduced for a commercial process. The total Project Rulison cost will be approximately $5.9 million. At such prices, nothing can possibly be prices, nothing can possibly be commercial; however, as outlined in the paper, these costs can come down in a paper, these costs can come down in a logical step-wise fashion to an economic number. A nuclear explosive with a design yield of 40 kilotons was emplaced and detonated in a 10-3/4" casing at a depth of 8426' below ground surface and detonated on September 10, 1969. A preliminary appraisal of the data taken at shot time indicate that the explosive behaved as predicted. The explosion was completely contained underground as predicted and no major seismic damage occurred. The post-shot reentry program, in the spring of 1970, will include reservoir testing to determine the degree of stimulation achieved. Introduction The greatest challenge to the oil industry has always been how to make available oil and gas at an economic rate. The increasing costs of exploration and the impending shortage of natural gas have made the economic development of marginal resources not only attractive, but necessary.

Project Bronco has been proposed as an experiment to determine whether nuclear explosions can be used in the recovery of oil from deep oil shale deposits. The experimental objectives of Bronco are: to evaluate the overall feasibility of nuclear breaking followed by in situ retorting; to investigate the gross physical effects of a nuclear explosion in oil shale; and to assess the role of radioactivities in the production of oil by in situ retorting. A proposed experimental site in the Piceance Creek Basin of Northwestern Colorado is described. Plans for site preparation and for emplacement and detonation of the explosive preparation and for emplacement and detonation of the explosive are discussed, as are studies to be made of the underground heat and radioactivity, of the geometry of the nuclear chimney, and of the fracturing of the oil shale. Preliminary plans for oil recovery from the nuclear chimney are reviewed. Before this application of underground nuclear explosions can become commercially feasible, a variety of technical problems must be examined. Some of these are related to nuclear explosion effects, others to the recovery of oil from the broken rock. Consideration of these factors is followed by a discussion of some long-range technical aspects for the development of a commercial technology.