OIL-IMPREGNATED SANDSTONE BETWEEN DIRTY DEVIL AND COLORADO AND GREEN RIVERS GARFIELD AND WAYNE COUNTIES, UTAH

Transcription

1 OIL-IMPREGNATED SANDSTONE BETWEEN DIRTY DEVIL AND COLORADO AND GREEN RIVERS GARFIELD AND WAYNE COUNTIES, UTAH Paper Presented to Rocky Mountain Section, American Association of Petroleum Geologists, Annual Meeting Albuquerque, New Mexico February 26, 1969 By Joe L. Bowman Geologist Federal Resources Corporation Newcastle, Wyoming (Field work and presentation of paper sponsored by Utah Geological Survey) Includes prints of Slide 2 (Geologic Map) and Slide 11 (Isopach Map) \

2 OIL IMPREGNATED SANDSTONE BETWEEN DIRTY DEVIL AND COLORADO AND GREEN RIVERS, GARFIELD AND WAYNE COUNTIES, UTAH By Joe L. Bowman (Paper presented to Rocky Mountain Section American Association of Petroleum Geologists' Annual Meeting, Albuquerque, New Mexico, February 26, 1969) This paper presents the results of two months of field work done as a part of the Utah Geological Survey's continuing inventory of the mineral resources of the state of Utah. Prior to this field work. Survey field parties had worked in the area intermittently in 1967 and 1968 laying the ground work for this more comprehensive study. The Utah Geological Survey has recently coined the name "Tar Sand Triangle" to describe the area lying between the Dirty Devil and Green and Colorado Rivers within which a great abundance of oil impregnated outcrops are found. (Slide 1, Index Map.) As originally conceived the apex of the triangle pointed south and the base was arbitrarily drawn across the northernmost of the oil impregnated outcrops. In a broader sense the Tar Sand Triangle is much larger and is obtuse rather than equilateral with its apex pointing westward towards Hanksville. It is bounded on the northwest by the San Rafael Swell on the southwest by the Dirty Devil River and on the east by the base of the triangle, the Green River. This broader triangle also seems appropriate in that the majority of wells drilled within this area reported "dead oil" stain in thicknesses ranging from 10 to 200 feet from stratigraphic and lithologic equivalents of the oil impregnated outcrops. (Slide 2, Geologic Map; Slide 3, Legend.) Here we have a geologic map of the area of field work. On this and subsequent lantern slides the legend portion will be removed soon after we first project them, so check the legends immediately for any explanations.

3 -2- The area of investigation is remote, desolate and extremely rugged. Maximum relief is about 3700 feet with over 3000 feet of stratigraphic section exposed. The rocks range in age from Pennsylvanian to Jurassic. (Slide 4, Cataract Canyon.) Here just above the Colorado River in Cataract Canyon are vertical cliffs of the Hermosa formation of Pennsylvanian age overlain by the ledgy Rico formation, which is basal Permian. The upper third of the canyon is the basal portion of the Permian Cedar Mesa Sandstone. (Slide 5, Dirty Devil.) At the lower left of this slide we see the bright white of the top of the Cedar Mesa cut by the Dirty Devil River. Above this is the reddish-brown Organ Rock tongue and then the massive dirty grey cliff of the White Rim formation, both Permian. The Triassic Moenkopi forms the next reddish-brown and ledgy slope and blends into the lower portions of the shales of the Chinle. Perhaps you can see a faint gray streak half way up the far slope. fonrration, mistakenly called Shinarump in local usage. This is the_mossback. A long slope of Upper Chirle extends upward to the vertical cliffs formed by the Wingate formation, the uppermost Triassic age formation. Then ledges of Jurassic Kayenta cap the cliffs (Slide 6, Navajo Butte) to be covered back from the rim by Jurassic Navajo sandstone which forms the uplands with an occasional butte rising above the gently rolling topography. Oil impregnation occurs in the Permian rocks of the Tar Sand Triangle, mostly in the White Rim Sandstone immediately below the Triassic Moenkopi Formation. Less important and genetically related deposits occur in the Cedar Mesa Sandstone below the White Rim.

4 » -3- The only locality where there is a broad exposure of the White Rim formation is in Elaterite Basin. Ordinarily this formation is exposed only in a narrow band along miles of appropriately named, near vertical cliffs. (Slide 7, Cove area.) Over 80 percent of the Permian outcrop area on the geologic map is the erosional surface of the Cedar Mesa formation. Of the faults shown on the map, most have displacements in the order of 25 feet. The largest are those bounding the graben just southwest of Teapot Rock. These have about 100 feet of throw. At only one place in the area could asphalt accumulations be clearly related to faulting. This is the small deposit at Poison Spring Canyon west of the Dirty Devil River where the oil is clearly confined to a narrow zone paralleling the fault plane. There is a fault associated with oil accumulation at Fault Point, but this appears to be a coincidence of cutting a stratigraphic trap rather than the fault being the trapping mechanism. (Slide 8, Diagrammatic X-Section.) On the screen is a northwest to southeast diagrammatic cross section showing the regional relationships of the Permian rocks. The White Rim Sandstone and Cedar Mesa Sandstone are massive sandstone bodies separated by the northwest-extending Organ Rock Tongue of the Cutler Formation. The White Rim is an extension of the DeChelly Sandstone. r _ The major oil deposits were originally trapped at the up-dip pinchout of the White Rim Formation. There are also scattered minor occurrences trapped in two ten foot beds of Cedar Mesa Sandstone which intertongue with the basal Organ Rock. The Cedar Mesa is a white to light grey, fine to coarse grained, aeolian sandstone. It is about 750 feet thick.

5 -4- The Organ Rock is composed of thin-bedded, water-laid, red siltstone, sandstone and shale. Its outcrop thickness varies from 120 feet in the vicinity of Teapot Rock to 250 feet along the southern mesas adjacent to the Dirty Devil River. It pinches out in the sub-surface just north of the area of field work. The White Rim Sandstone is a clean, white to buff, fine to coarse-grained, very friable sandstone. The middle...and lpwer portions of the unit are aeolian but c the_upper portion is definitely marine. beautifully preserved planes of top-set For example, ripple marks are common and bedding can be walked for up to 1000 feet before they plunge off, unbroken into fore-set bedding. Distribution and direction of dips on cross bedding indicate that the water currents transporting sediment during deposition of the upper White Rim came from the north and northwest and then were turned to the southwest upon striking the White Rim shore line adjacent to the anticline shown on this slide (Slide 9 index with anticline.) The existence of this anticline is interpreted on the basis of: anonomalously thin Organ Rock along its northwest flank, pinchout of the White Rim against it, and by poorly defined regional thinning of the Moenkopi over it. On the outcrop one gets the impression of turnover, or at least a change in present dip in the area where this anticline is postulated but the character of the exposed Cedar Mesa makes its demonstration difficult. (Slide 10 Cedar Mesa east of Tar Cliff.) A thin ring of White Rim sediments were deposited all around this anticline including areas east of the Colorado River. These outcrops are mapped as either White Rim Formation or the stratigraphic and lithologic equivalent Hoskinni member which has been assigned a Triassic age and placed at the base of the Moenkopi.

6 -5- An isopach map (Slide 11, Isopach map, Slide 12 Legend) was constructed on the basis of some 75 measured sections. This map shows a major development of White Rim sand paralleling and directly adjacent to the pinch-out of the formation. Note the anticlinal axis indicated in red. This is a very unusual anticline and it is something of an enigma no matter how you attempt to interpret it. It is about a quarter to a half-mile wide, about three miles long, and has about 100 feet of relief. Moenkopi beds lap up on its flanks but are also in angular unconformity against other horizontal Moenkopi...beds. (Slide 13, unconformity.) In this picture we are looking along strike on the north flank of the anticlirie. The rock surface exposed in the foreground is the top of the White Rim which is dipping at about 13 degrees to the east or right hand portion of the picture. Through the middle of the picture runs a band of buff colored material that appears to be shale or talus. Actually this material is Moenkopi that has been subjected to rather severe chemical and physical changes due to the proximity of the oil-impregnated beds. It is not a simple bleaching or discoloration, Incidentally, a similar phenonoma occurs at the top of the Organ Rock formation whenever it is adjacent to oil impregnation. Usually this envelope of discolored beds is buff, tan or khaki in color, sometimes with overtones of orange. Directly in the center of the picture you can see discolored Moenkopi beds in angular unconformity with nearly horizontal younger Moenkopi beds which are red. At the extreme right of the picture all of the beds are concordant including the red Moenkopi, the buff Moenkopi, and although you can't see it, the White Rim. Despite the evidence indicating a simple structural history to this feature (Slide No. 14, ripple marks) such as here where ripple marks are dipping at 12 degrees

7 -6- on the upper surface of the White Rim, when one is working around this anticlinal feature, one has the distinct impression that there is also stratigraphic build-up coincident with the anticlinal axis. When walking up the little stream that drains Elaterite Basin, the beds seem fairly regular and flat in relationship to the stream gradient until you approach the anticline. Suddently there is more cross-bedding and thickening of units. When you cross the axis of the anticline, the 25 to 30 feet of rock between the stream bed gradient and apparent top of the formation increases to over 150 feet, all White Rim; and here the stream has not yet cut down to the Organ Rock. > Looking at the isopach map again it appears that the little anticline in Elaterite Basin was a shoal area which caused an off-shore bar to form during White Rim time. A thick pod of clean sandstone formed over and in the lee of this shallow positive feature. The anticline had a very short period of growth. In the time required to deposit about 100 feet of Moenkopi sediments, the feature had grown and then been completely overlapped without truncation or other erosion. It never grew again. Just north of the Elaterite anticline you will observe a number of wiggles in the isopachous contour line. This reflects a swarm of small bars, all oil impregnated, with relief of 30 to 50 feet and lengths in the order of a mile or two. There is no structural control affecting their deposition. This feeling of thickening within the White Rim over the anticline in Elaterite Basin is re-enforced by the stratigraphic relationships observed in Red Cove. (Slide No. 15, Red Cove) Here we are looking at the north side of Red Cove. The mesa cap is Mossback conglomerate. Underlying it is approximately 300 feet of red Moenkopi, and 50 feet of buff Moenkopi. The bluish-grey is the White Rim formation

8 -7- which is over 250 feet thick. Under the White Rim is another buff zone some 50 feet thick that is altered Organ Rock and then 80 feet of red Organ Rock before the white of the Upper Cedar Mesa is exposed in the bottom of the valley. The bluish-grey is typical of the weathered appearance of saturated outcrops in this area. Here in Red Cove the outcrop is heavily saturated for a thickness of 250 feet over a distance of more than 2 miles. Oil has migrated out of the White Rim through fractures and joints down into the Cedar Mesa formation and has impregnated that formation to a depth of approximately 80 feet. Oil in the Cedar Mesa occurs in all exposures in the valley bottom within our view in the picture ending at a line at the right hand edge of the picture. Oil has also impregnated all sand lenses or arkose beds which have any semblence of porosity and permeability in the intervening Organ Rock as well as in the basal beds of the overlying Moenkopi. The same conditions hold true at Teapot Rock. As you trace the White Rim to the right in the picture, the rapid thinning at the top of the formation is apparent. In contrast to the unconformable relationships observed around the little anticline in Elaterite Basin, the White Rim here in Red Cove gains section at the expense of the basal Moenkopi without structural complications. The basal Moenkopi beds lap out against the stratigraphic build-up at the top of the White Rim. There is no angular unconformity. A similar thickening occurs at the base of the White Rim. It is not as apparent in the picture as the thickening which occurs at the top of the formation, but above the little knoll of Cedar Mesa in the left center of the picture the base of the White Rim truncates and cuts into the top 25 to 50 feet of the Organ Rock.

9 -8- Following the White Rim outcrop on to the extreme right of the picture, all that remains is a thin white ledge some 25 feet thick. Just off the picture, the true White Rim lithology of clean, white sandstone blends and changes to a red, silty and arkosic sandstone of typical Organ Rock character. Note that small east pointing spur of Permian about three miles north of the end of the green coloring noted on the map at Red Cove (Slide No. 16, Lizard Rock). In this slide we are looking at that spur. In the lower left middle of the picture you see a point with a rounded ledge of red sandstone beneeth which there is a cliff of red siltstone and shale and then a bright white band of Cedar Mesa. This 25-foot rounded ledge of red sandstone is exact equivalent to the White Rim, but its lithology is that of the Organ Rock. A sharp facies change is apparent. A mile or so north of this point the clean white sandstone and vertical rather than rounded cliff character of the true White Rim lithology returns. Thus the pinch-out of the White Rim can be mapped at this locality, on the north side of Red Cove, and on both sides of the spur separating Red Cove and Teapot Rock. The stratigraphic relations at Tar Cliff suggest that the exposed White Rim is close to the pinch-out which has been effaced by erosion a short distance to the east. At Tar Cliff the full section is impregnated, and although not as welldeveloped as at Red Cove, there is indication of bar development. As the good saturation is pursued around the corner to the southwest, the oil staining rises in the section, suggesting a fossil oil-water interface. To the north of Tar Cliff, as well as in the vicinity of Fault Point, you can see little patches of oil staining indicated on the map as being just barely separated

10 -9- from the line indicating the top of the Permian. These are indicative of oil, stratigraphically trapped in the up-dip pinchout of two Cedar Mesa sands which intertongue with the base of the Organ Rock. Weathering affects the degree of saturation. The outcrops are richest where vertical cliffs are exposed or at the heads of canyons. Mesa points and areas of broad surface exposure, such as the majority of Elaterite Basin and the \ area just south of Teapot Rock, have only weak residual stain. \ This weathering effect is a part of the reason for the area of weak staining southwest of Tar Cliff. However, there is another aspect in regard to this area and the good stain at The Cove and at Hatch Canyon. Note that these latter two areas seem to have no relationship to the isopach configuration. We will return to a consideration of these deposits after looking at the structure of the region. (Slide 17 Structure Map, and Slide 18 Legend) Regionally the Tar Sand Triangle is on the northwest plunge of the Monument Uplift. The rocks dip gently at one to three degrees to the northwest. At least as far as present day structure is concerned, Tar Cliff, Red Cove, Teapot Rock, and Fault Point all seem to occur on the crest of minor noses, but much of Elaterite Basin, Hatch Canyon, and The Cove are located in either a regional or synclinal structural position. Note also the number of dry holes reporting dead oil stain. It is probable that some of the other dry holes in this area also encountered staining, but it is not reported in the public record. Dead oil occurrences in the sub-surface seem to have no consistent relationship to the present-day structure, suggesting that configuration of

11 -10- off-shore bars similar to the one at Red Cove controls the sub-surface oil staining at the top of the White Rim or De Chelly. The oil entrapped in the pinchout of the White Rim appears to have been derived from the marine sediments of the Moenkopi and Kaibab formations. Migration for considerable distances seems likely considering the limited capability of these organically poor sediments to generate such large quantities of oil. The Henry Mountain syncline has been a negative area to varying degrees ever since Permian time. It has probably served as a structural barrier, leading one to believe that the main migration routes of the oil must have been from the north and northwest. The number of dry holes which have encountered dead oil stain between the San Rafael Swell and the Tar Sand Triangle would tend to support this hypothesis. Active oil seeps are found in several places in the Tar Sand Triangle. The main ones are in the northern portion of Elaterite Basin, with Hatch Canyon being significant also. Minor seepage has been found in the vicinity of The Cove. All of the seeps are in relatively low structural and topographic positions. All are associated with springs. Furthermore, all the oil seeps are more active in the spring of the year when water seepage is more active rather than in the middle of summer when the desert heat would be expected to soften the oil on the outcrop and allow it to flow more readily. It is suggested that as a consequence of physical decomposition of the winter-hardened oil, minute flakes of oil residue migraie down-dip from the main deposits. The oil is carried by percolating ground water and is deposited as

12 -11- secondary oil accumulations around springs and water seeps. Thus the area of weak saturation on the dip slope southwest of Tar Cliff and the larger deposit at The Cove are thought to have been derived from Tar Cliff. Hatch Canyon has extensive areas of active seepage which vary on a seasonal basis. (Slide 19, Hatch Canyon) Here in the bottom of Hatch Canyon the stream has cut into the top of the White Rim. It is reported that a previous field party who visited this spot in the early spring found all of these cross beds actively seeping oil. Walking was a sticky process. As you can see in this picture taken in early September, the oil had hardened and dried. Only pin-point oil seepage was found in the area oozing out with minor amounts of water. Like other areas of oil-impregnated sands in Utah, the reserves of the Tar Sand Triangle become overwhelming. For instance, if you were to mine the two-and-a-half miles of outcrop exposed just within Red Cove for a distance of only 50 feet back from the toe of the cliff, you would be handling rock containing over one million barrels of oil. If you go back an additional 5 00 feet, you will have another 32 million barrels. The major bar is about 10 miles long and one-and-a-half miles wide. If we use an average thickness of 100 feet of saturated section containing 17 gallons of oil per ton, the reserves for Teapot Rock, Red Cove and Elaterite Basin exceed one billion barrels of oil. Incidentally, for you who are unfamiliar with this mining terminology, 17 gallons per ton just about equates to 60% saturation in a sandstone containing 23% porosity. Look at the structure map again. Just west of Red Cove you can see two wells which reported 140 feet and 150 feet of dead oil stain when they were drilled.

13 If these wells form one continuous oil-impregnated sandstone body with the majdr bar mapped iri the outcrop, you can readily understand why"reserves""of bitlnplace for the area have been estimated at 3.5 to 5.0 billion barrels. In summary then: A large off-shore bar developed along the depositional pinchout of the White Rim formation. Oil apparently derived from the Moenkopi and Kaibab formations migrated up-dip to fill the bar. Late Tertiary erosion by the Colorado River breached this reservoir, allowing the more volatile constituents to evaporate and leaving behind an asphaltic residue of major proportions Secondary migration is currently moving portions of the oil down-dip with migrating ground water and depositing the oil around springs.

14 R.I3E SCALE - MILES

15 3

16 322 BOX ELDER 1~ \CACHE \ / \ \ \._A^ V-,/wEBER ) ^ I TOOELE -'<- /"SUMMIT WYOMING DAGGETT * X'SALT LAKE C % i \UTAH / J WASATCH DUCHESNE I UINTAH l r 1.11 IAR ) MV Si MILLARD II U Zl K : o BEAVER I liror I * *._2 - i O 1 0, * SAN JUAN \ 1 ^OOllAtr'Jl tins'- \ WASHINGTON! T-, I i HTANE 31 32#.J*. IN. MEX LEGEND 32 9 PETROLEUM-IMPRESNATED ROCK io zo ao 40 X^ GENERAL AREAS FIGURE Occurrence of Petroleum-Impregnated Rocks in Utah

17 324 KEY TO FIGURE 36 (Con.) Washington County 31. Virgin River 32. Hurricane Fault UTAH Summary Petroleum-impregnated outcrops are widespread throughout eastern Utah and less so in the west and southwest. Within and around the periphery of the Uinta Basin, in the northeast are grouped some of the best known "tar sands" in the United States, including the Sunnyside, Asphalt Ridge, and Whiterocks deposits. These and others in the Uinta Basin have been studied in substantial detail and have long been considered among the significant reserves of petroleum-impregnated rock in the United States. Less well known, but probably of equal or greater importance, are widely-distributed deposits in southeastern Utah, mainly along the flanks of breached anticlines such as the San Rafael Swell and the Circle Cliffs Uplift. The well-known Rozel asphalt deposits near Great Salt Lake have only a little associated impregnated rock, incidental to the asphalt itself. Several reported impregnated outcrops are neighter shown on figure 36 nor described later because too little is known about their characters and locations. Among these are an asphaltic limestone reported by Abraham (1, p. 164) and Barb and Ball (4, p. 13) as underlying a very large area, east from Thistle to Antelope Creek and from Colton to the Strawberry River, and an asphaltic limestone near the town of Clear Creek (1, p. 162). Oil-impregnated Paleozoic formations are reported in several mountain ranges of western Millard and Juab Counties in western Utah, but with too little information to help locate these possible deposits on the map. Reserve figures are published only for the Whiterocks, Asphalt Ridge, Sunnyside, and P. R. Springs deposits. These total 1,900 million to 4, 600 million barrels of bitumen in place. (Another, recent estimate by Covington (12) is substantially lower.) In Uintah and Duchesne Counties locations within the area of the Uintah Special Base and Meridian survey are designated "USM" in this report. Locations in these and adjacent counties but not in the Uintah survey are shown as "SLM" (Salt Lake Base and Meridian). The Salt Lake Base and Meridian covers the rest of the State. ROZEL (1) Location On the northeast shore of Great Salt Lake, in T 8 N, R 7 W, Boxelder County. Description Mounds of petroleum-saturated oolitic sand and clay along the lake shore. and tarry oil from Quaternary (Salt Lake Group?) sediments. The bitumen is asphalt The area of oil-impregnated rock is very small. Development History The seeps were known before Small amounts of asphalt have been mined and shipped from the the area, and small quantities of oil have been produced from several of the 20 or more wells in the area. Reserve No published information.

18 323 KEY TO FIGURE 36 (Con.) 9. Deep Creek Nose 5rl.O. Asphalt Ridge 11. Red Wash 812. Raven Ridge 13. Chapita Wells 14. Myton Bench (partly in Duchesne County) 15. Dragon-Asphalt Wash/^L f^r-k) 16. Seep Canyon 17. Hill Creek ~fe\?>. Sunny side Carbon County Grand County -/irl9. P. R. Springs (Pear Springs) (partly in Uintah County) 20. Salt Wash 21. Tenmile Wash Emery County 22. San Rafael Swell Wayne County 23. Sweetwater Dome (partly in Emery County) 24. Capitol Reef ~M 25. Elaterite Basin. -1 : c - ' >/c_-l Garfield County 3 2 6^ ijatch-canyon 27. The Cove, 28. Circle Cliffs San Juan County 29. White Canyon 30. Mexican Hat