Physical results of research drilling in thermal areas of Yellowstone National Park, Wyoming

TLDR

Abstract

Length. : 1 inch = 2.54 centimetres 1 fuot = 0.3048 metres 1 mile = 1.61 kilometres Tempemture: OC = 5/9 (°F -32) °F = 1.8 (OC) + 32Pressure: llb/in 2 (psi)= 0.06895 bar = 0.06805 atm = 0.07031 kglcm2 All pressures are absolute, with 11.1 psi (0. 78 kglcm 2 ) added to gage pressures, even though actual ground-level air pressures range from 11.5 psi at the Mammoth {Y-10) hole to 11.0 psi at the Mud Volcano {Y-11} hole.analysis of our data indicates that four of our drill holes affected nearby springs, generally converting them temporarily into geysers.Our conclusions from Yellowstone indicate that physical relations in many commercially explored geothermal reservoirs are not as uniform as routine postdrilling measurements have indicated. SCIENTIFIC OBJECTIVESThe drilling program in Yellowstone was designed to provide the following: 1.The best possible estimates of original ground temperatures and temperatures within the holes after drilling was completed.2. Data on wellhead pressures (or water levels) for calculations of down-hole pressures.3. Continuous cores to determine the stratigraphic sequence, and subsequent mineralogical and chemical analyses leading to a description of rock-water interactions in hot-spring systems.4. Continuing access to the drill holes to allow intermittent sampling of fluids, measurement of temperatures and in-hole pressures, and testing of geophysical logging devices.As the drilling program progressed, the limitations of our wellhead pressure data became clear.The data were neither as reliable nor as accurate as we would have liked, and furthermore, no down-hole pressure measurements were made during the drilling program.Equipment for measuring down-hole pressures was constructed after completion of the drilling (Fournier and Truesdell, 1971) and was used to determine the '"This is essentially what happened at the Norris drill bole lC--moa-theCanlegielnstitution in 1930(Fenner.1936,p. 286).The situation there was remedied by pumping5tonsofc:ement down the casing and out into the fonnation!steam mixture from open drill pipe in Y-5 (Rabbit Creek) drill hole, August 20, 1967.The "bursting" .effectresults from flashing of superheated water erupted to atmospheric pressure at and just above the top of the drill pipe.The eruption phase typically follows a brief interval of quiet overflow such as shown in A and passes rapidly into the near-vertical ejection of steam: and water, such as shown in C. C, Eruption of water and steam above the top of the drill tower, Y-9 drill hole, Norris Basin.When the thermistor gear was inoperative, temperature profiles were made with successive runs with a maximum thermometer-a tedious exercise.s Although the thermometer could be jarred when being raised through the bit, norm~lly we knew about how far the bit was above the bottom of the hole, and thus could ratse the thermometer very slowly through the bit.1 "Bedrock" is the uppermost lava or ash flow of each hole.4 Psig equivalent of depth of water level below surface. 2 Rise in static water level/total depth; difference between ground and water level 5 Depths and diameters of casing not specified.ignored.6 233 psia at -488 ft; point B of figure 18 suggests bottom-hole pressure of at least 254 3 Not measured.psia at -516ft.Vertical pressure gradient 2 0.3'7• .01.19?.20 .12.30.19 .