TID-4500, UC-35 Nuclear Explosions — Peaceful Applications L5 LASA/RENCE UVERMORE LABORATORY Unh*^atCa*xrik/UmrnK^Cm>nl4/94550 UCRL-51163 POSSIBLE EFFECTS OF THE RIO BLANCO PROJECT ON THE OVEkLYING OIL SHALE AND MINERAL DEPOSITS F. Holzer D. O, Emerson MS. date: December 27, 1971 — NOT.CE- Thlt report was prepare? «*i an account of work sponsored by the United States Government. Neither the United States no? tha United States Aiomic Energy Commission, nor any/ of sheir employees, nor any of their contractors, subcontnctors; or their employees, maJcai vat 1*f*«M*y, »*gs«s,«s irnqKaA, « mawata any lags] liability or responsibility for the accuracy, com­ pleteness or usefulness of iny {information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. wawsimw OF THIS oocumm is ONI Contents Abstract 1 Introduction 1 The Hio Blanco Project and Site Geology 3 Proposed Phases of the ?roject 3 Subsurface Geology and Mineral Distribution 6 Stratigraphy 6 Mineral Distribution ~i Hydrology 10 Effects of Rio Blanco 10 Subsurface and Near-Surface Effects 10 Explosion-Induced Fault Motion 20 Effects on Mines 22 Summary 25 Acknowledgments 25 References 26 •iii- POSSIBLE EFFECTS OF THE RIO BLANCO PROJECT ON THE OVERLYING OIL SHALE AND MINERAL DEPOSITS Abstract The proposed Rio Blanco nuclear deto­ We expect no subsurface separation of the nation for stimulating natural gas produc­ rock layers in the Green River Forma­ tion (and the subsequent development of tion. A seismic reflection survey shows the Rio Blanco Unit) has raised questions that the closest indication of a subsurface about possible harmful effects of the ex­ fault occurs about 2 miles from the Rio plosions on the overlying formations con­ Blanco location. Data from the Nevada taining oil and sodium minerals. We Teat Site show that no fault farther than show that fractures will extend to perhaps 6000 ft from a 100-kt explosion would 400 ft above tht> upper explosive. Since undergo explosion-induced displacements, at least 2300 ft separates the gas-bearing and hence none is expected from Rio strata from the oil shale and minerals, Blanco. At the mine closest to Rio no fractures will extend into the forma­ Blanco, we predict the peak acceleration tions containing these resources. We to be 0.06 g. Since this was about the calculate a spall depth of about 170 ft; same acceleration experienced by this our experience indicates that no harmful mine from the Rulison explosion, Rio effects will occur as a result of this spall. Blanco should not cause any mine damage. Introduction As part of the Plowshare Program's tial phase are now being defined, and the use of nuclear explosives to stimulate environmental impact is being studied. the recovery of natural gaa from low- The progress of the plans for the first permeability formations, the CER- phase of the Rio Blanco Project, as well Geonuclear Corporation, together with as for the subsequent unit development, the Equity Oil Company, has proposed has raised concern among various corpo­ a project whose initial phase consists of rations that are attempting to develop the simultaneous detonation in a single economic techniques for recovering oil emplacement well of three 30-kt nuclear and other minerals from the oil shale explosives in the Fort Onion and deposits that are distributed in various Mesaverde Formations of Colorado's amounts in different parts of the Piceance Piceance Basin. The details of this ini- Basin,2 Emplacement well Parachute Greek Member Green River Formation (oil shale and minerals) 7MZL -Orange Marker 2900 3000 -- 4000 -- Wasatch Formation 5000 -- 53«) Fort Union Formation Oil shale 6000 (>I0gal/ron) 6180 Gas-bearing Mesaverde Formation sandstone 7000 H Fig. 1. Generalized geological cross section at the Rio Blanco site showing the main gas-bearing formations as well as oil- and mineral-containing formations. Depths indicated are in feet; the horizontal scale is equal to the vertical scale. -2 Our approach is to examine the poten­ 4) Explosion-induced motion on exist- tial impact of Rio Blanco on the geologic ing faults. formations containing the oil and the 5) Damage to existing mines. sodium minerals nahcolite and dawsonite. Figure 1 shows the relation of the pro­ The premise on which the conclusions are posed Rio Blanco Phase-1 project to the based is that if these formations are not geologic formations containing oil shale fractured as a result of the explosions and minerals. The gas-bearing forma­ or attendant phenomena, then the re­ tions that are planned for nuclear stimu­ covery of the oil and minerals will not lation lie, in general, at a depth greater be affected. than 5000 ft, while the oil shale and We examined the following possi­ mineral-containing rocks are, in general, bilities: encountered in the 400- to 3000-ft interval. The main conclusion reached from the 1) Direct fracturing from the explosion studies presented in the following sections zone into the oil shale and the for­ is that the separation of more than 2300 ft mations bearing sodium minerals. between the detonation zones and the 2) Extent and depth of surface fractur­ mineral-containing formations serves ing or "spall." as an effective barrier between them and 3) Subourface separation of the various makes any disturbance of the latter highly strata and layers. unlikely. The Rio Blanco Project and Site Geology The location of Phase 1 of the Bio Blanco simultaneously, the details of the Phase-2 Project, as well as th<? unit proposed for explosions are not yet formulated. The subsequent development, is shown in nature of this phase will depend on the re­ Fig. 2. Phase 1 {hereafter referred to sults from Phase 1 and on progress made simply as Bio Blanco) ie located 52 mites in developing explosives suitable for se­ north of Grand Junction, Colo., and 31, quential detonation. For example, it 30, and 37 miles from Rangely, Meeker, might make most sense at some locations and Rifle, Colo., respectively. to use three 100-kt explosives (emplaced Figure 3 shows the location of the Rio in the same bole) that would be detonated Blanco Unit with respect to the Piceance a number of minutes or longer apart so Basin boundaries and the approximate as to stimulate the largest vertical thick­ locations of the proposed P.hase-2 ness of gas-bearing formation with the explosions. minimum practical ground motion; in other locations a smaller or perhaps larger yield PROPOSED PHASES OP THE PROJECT might well be indicated. An explosive that While Rio Blanco is planned to consist is sufficiently rugged for sequential deto­ ot three 30-kt explosive* spaced approxi­ nation has not yet been developed, how­ mately 420 to 450 ft apart Eiid detonated ever, and proceeding to Phase 2 with Fig. 2. Map showing distances from the Rir Blanco emplacement well to nearby com­ munities. The Rio Blanco Unit is also outliaed. -4- j|g^y^ ® Rio Blanco Phase-1 location kfe- O ApProx'mate Phase-2 location Fig. 3. Location of the Rio Blanco Unit within the Piceance Creek Basin. Tht Phase-2 locations snown are approximate only. -5- simultaneous detonations should net be scription of these topics is necessary to ruled out at this time. evaluate the potential impact of the Rio Phase 3 is presently contemplated to Blanco Project. consist of 20 to 60 well stimulations whose Figure 4 depicts a cross section of the nature and location will depend on the re­ subsurface geology along a;i approximately sults from the previous phases. A more east-west line through the Rio Blanco em­ extensive development of the unit, con­ placement well, and Fig. 5 shows the sisting of stimulating perhaps an addi­ cross section in a generally northeast- tional 100 wells, would follow. southwest line for the western portion of the unit. These figures show that the beds SUBSURFACE GEOLOGY AND MINERAL dip and thicken from west to east and from DISTRIBUTION south to north. Generally, the Evacuation The general subsurface geology and Creek Member of the Green River Forma­ mineral attribution of the Piceance Creek tion is exposed at the surface. However, Basin have been studied extensively and are the Parachute Creek Member outcrops in 3 described in the literature. We will not the extreme southwestern corner. attempt to duplicate this information here Stratigraphy but will focus our attention instead on the The stratigrapbic horizons observed Rio Blanco Unit, for which a brief de­ near the emplacement well for Rio Blanco 6000 ft ~-~^-"ir-- Mahogany Zone-* _ m . _2range_Mar|(er (Base of lean oil shale) 4000 ft 2000 ft Sea level West last Fig. 4. Geologic cross section along a general east/west line through the Rio Blanco Unit and the Phase-1 emplacement well. 6000 ft "TCFarige Marker 4000 ft (Base of lean oil shale) 2000 ft Sea level Southwest Northe st Fig. 5. Geologic cross section from southwest to northeast of the western par. of the '. io Blanco Unit. are at a depth that is about average for the Formation, a mudstone and shal J unit unit. At that location alluvium deposits containing intermitteat and infr* quent in the stream bed are found bet'veen the lenses of sandstont carrying g 9 and surface and a depth of about 100 ft. Be­ water, extends from about 3000 to 5360 ft. tween 100 and 400 ft below the surface is Below this level are gas-bearing sands of found the Evacuation Creek Member of the Fort Union and Mesaverde Formations the Green River Formation—a barren in which the proposed nuclear detonations sandstone, siltstone, and mudstone forma­ will take place.