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HomeMy WebLinkAboutKotzebue Geothermal Project Geological Analysis 1981 KOTZEBUE GEOTHERMAL PROJECT Geologic Analysis BY ARLEN EHM 2420 Foxhall Drive Anchorage, Alaska 99504 January 1981 PROPERTY OF: Alaska Power Authori ori 834 W. 5th Ave. : Anchorage, Alaska 99501 Prepared For The State of Alaska Division of Energy & Power Development 338 Denali : Anchorage, Alaska 99501 Energy Systems, Inc. P.O. Box 6065 Anchorage, Alaska 99502 ESI - Alaska DEPD BRU 08-71-7-500 ALASKA POWER AUTHORITY TABLE OF CONTENTS Drilling Depths. .. 2... . 2... ee ee Drilling Costs... .. 2... ee ee Conclusions. .. 2... . eee ee Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure LIST OF ILLUSTRATIONS 1 Location Map - Kotzebue Area... .........2004 2 Location Map - Baldwin Peninsula. ............ 3 Gravity Survey & Profile Over a Dome With a Crystalline Rock Core. 2. 1 ee ee ee ee 4 Gravity Survey Over a Salt Domew . . 2... 2... 2. ewe 5 Magnetic Survey & Profile Over a Dome With a Crystalline ROCK CONC goes 0 5 6 Magnetic Survey Over a Salt Dome... .........0. 7 Reflection Seismograph Survey. .........2.22280 8 Seismic Record Section... .. 2... 2... ee ee eee 9 Surface Geological Map... 2... 2. eee eee ew eee 10 Nimiuk Point No. 1 Columnar Section. ........... 1 13 15 32 16 17 18 18 19 19 20 20 2] Figure Figure Figure Figure Figure Figure Figure Figure Figure im 12 13 14 15 16 7 18 19 Page Cape Espenberg No. 1 Columnar Section. .......... 23 Generalized Temperature Profile. . : SEN 24. Nimiuk Point No. 1 Temperature Profile . ta et, Cape Espenberg No. 1 Temperature Profile. ........ 26 Formation Test Data... ....-2.-22-2-- 202 ee eee 27 Nimiuk Point No. 1 Electric Log. ...........2.2. 28 Nimiuk Point No. 1 Formation Water Chemistry ....... 29 GV ACY Don na Ho oe aw tel aoe eal ceo HO 30 Structural Cross Section From Kotzebue To Nimiuk POUNE NOLIN 2 oo elise © ee (ee oo. MFCM o . wlll 31 INTRODUCTION This study is designed to determine those geologic parameters necessary for a feasibility study of the uses of geothermal energy for space heating the town of Kotzebue. These parameters include the availability of formation water as well as the water's temperature, chemical composition, pressure, and the depth and cost of the wells to be drilled in the immediate Kotzebue area. Data utilized in this study include publically available geologic and geophysical reports, reports and data from test wells as well as Proprietary seismic surveys and geologic studies. Appreciation is hereby extended to Chevron, USA, for releasing certain of their data for use in this study. A special thanks is extended to Mr. E.K. Espenschied and Mr. C. Lyon for providing additional information through discussion. We wish to thank the NANA Corporation for obtaining the release of the Chevron data. GEOLOGIC SETTING Kotzebue lies at the northwestern tip of Baldwin Peninsula and is nearly surrounded by marine waters of Kotzebue Sound and Hotham Inlet. Baldwin Peninsula is entirely covered by Quaternary deposits which completely obscure the bedrock (Figures 1 & 2). Prior to the drilling of the Chevron (then Standard 071 Company of California) test wells during the winter of 1974 and 1975, all interpre- tations of the subsurface geology in the area were made by projections based on geologic outcrop maps, aeromagnetic maps and gravity maps. Seismic maps have been used to a lesser extent since the most critical seismic data within the immediate Kotzebue area are proprietary. Diagrams of gravity, aeromagnetic, and seismic surveys are given in Figures 3-8. Figure 18 is a gravity map of the Kotzebue Region. A seismic profile through Kotzebue is given in Figure 19. Geologically, Kotzebue lies within the Selawik Basin between two highly active tectonic areas. To the south of this basin is Seward Penin- sula with a diverse suite of rocks ranging in age from Precambrian to Recent that includes sedimentary, metamorphic, and igneous units. Seward Peninsula contains numerous highly mineralized zones. To the north of Selawik Basin are the Baird Mountains and De Long Mountains, the westward continuation of the Brooks Range. Generally speaking, these mountains are comprised of sediments ranging in age from middle Paleozoic to Cretaceous with some Mesozoic age intrusives (Figure 9). In the Selawik Basin and to the east in the Kobuk River Valley, Cretaceous age sediments outcrop. Hope Basin is present to the west of Selawik Basin and contains sediments of Tertiary age resting unconformably on older rocks. That is, rocks of the intervening ages are absent and a time gap is present in the rock record. This Tertiary age basin thins eastward towards Kotzebue and is absent where the first outcrops appear east of Kotzebue. The area south of Kotzebue Sound and Selawik Lake is comprised mostly of outcrops of volcanic rocks, which are extrusive igneous rocks, and intrusive, or deep-seated igneous rocks chiefly of Cretaceous age and younger. Outcrops of crystalline (nonsedimentary igneous and metamorphic) rocks as old as Precambrian are present further to the south and west. Bouguer gravity maps, however, and to a lesser extent, aeromagnetic maps, show the Kotzebue Sound area to be separated from this Seward Peninsula crystalline terrain. This suggests that the rocks present in the subsurface at Kotzebue should be similar to those to the east in the Kobuk River Valley and to the west in Hope Basin. The faults that are present on the seismic sections are primarily of early Tertiary age. Seismic activity is considered minimal in the Kotzebue area at present. CHEVRON TEST WELLS During the winter of 1974 and 1975, Chevron drilled two exploratory wildcats as a part of their exploratory agreement with the NANA Corporation. These were the Nimiuk Point No. 1, drilled to a total depth of 6311 feet and the Cape Espenberg No. 1, drilled to a total depth of 8373 feet (Figure 2). Although both tests were dry holes with respect to the finding of commercial quantities of hydrocarbons, they did provide useable data for integration into the regional geologic interpretation of the area. The Nimiuk Point No. 1 will be considered the analog for any test well proposed for this study because of its close proximity to Kotzebue. Both tests began drilling in Quaternary deposits and penetrated conglo- merates, sandstones, siltstones, clays and minor lignitic coal of Tertiary age (Figures 10 & 11). In the Nimiuk Point No. 1, these Tertiary deposits were about 5600 feet thick and at Cape Espenberg No. 1, they were about 4700 feet thick. These rocks unconformably overlie volcanic rocks of probable Cretaceous age. In the Nimiuk Point No. 1, 40 feet of these volcanic rocks were present as andesite porphyry and basalt while at Cape Espenberg No. 1, about 2950 feet of andesite porphyry, basalt, tuff and volcanic agglomerate were encountered. Another unconformity separates these crystalline rocks from the under- lying quartz mica schists, and partially metamorphosed dolomites, and lime- stones (marbles) of probable middle Paleozoic age. More than 300 feet of these rocks were drilled in each test before reaching total depth. Rocks considered to be correlative to these metamorphosed rocks outcrop on the west side of Eschscholtz Bay 30 miles south of the Nimiuk Point No. 1. The metamorphosed rocks present in the bottom of these two test wells are not considered potential reservoir rocks for hydrocarbons. Correlation of these rocks with the known surface geology of the area indicates that better quality reservoir rocks are not likely to be present below these metamorphosed rocks. Drilling was, therefore, terminated. One drill stem test was conducted on the Nimiuk Point No. 1 within the interval 3537-3755 feet. During the flow periods of the test, a net rise of 2190 feet of fluid was recorded, including drilling mud, muddy salt water, and clear salt water. The temperature recorded for the produced waters was 107°F (42°C). At the bottom of the hole the maximum measured temperature was 162°F (72°C) from a maximum recording thermometer and 159°F (70°C) from the continuous temperature log. In the Cape Espenberg No. 1, four drill stem tests were conducted with Only one providing useful information for geothermal purposes. A formation test, designated HFT No. 2, within the interval 7914-8128 feet recorded a net rise of 7414 feet of drilling mud, muddy salt water, clear salt water and sand. The temperature recorded for the produced water was 161°F (71°C). At the bottom of the hole the maximum measured temperature was 163°F (73°C) from both the maximum recording thermometer and the continuous temperature log. GEOTHERMAL POTENTIAL Geothermal Heat Source Although the two wildcats discussed above did encounter crystalline rocks near total depth, it should be noted that these are not true basement rocks. Metamorphosed limestone and dolomite were recovered from cores taken below these crystalline rocks. At the present time the depth to true base- ment can only be inferred. Whereas granites and other plutons are present in Seward Peninsula and the Kobuk River Valley as well as near Noatak to the north, any geothermal resource at Kotzebue must be in the relatively low temperature aquifers in the Tertiary age sediments. It is important to note that this project does not involve geothermal systems and geothermal wells as they are normally considered in geothermal exploration. That is, hot, deep seated igneous rocks, fault and frac- ture systems, influx of meteoric waters into the system, and resultant very hot waters and/or steam are not involved. Rather, this geothermal system must rely on large volumes of warm water that can be produced from a sedimentary basin where the original formation waters are trap- ped. Very hot crystalline igneous rocks are not involved and there is no charging action from surface waters. The sediments being considered as reservoir rocks for the warm waters are generally continuous throughout the area. The type of sediments in the two Chevron test wells leads to this conclusion as does an examination of the seismic records for the area. In contrast to surface aquifers which can be highly variable in their reservoir quality over small areas, the deeper reservoirs penetrated and tested by Chevron are considered to be continuous over the entire area. The potential reservoir rocks presumed to be present under Kotzebue should be continuous with the deeper sediments under Hope Basin. This should insure an adequate reservoir system filled with warm waters. Geothermal Gradient The geothermal gradients for the two test wells are above normal for sedimentary rocks. The temperatures recorded by the well temperature surveys must be utilized as they are the only temperature data available for geothermal studies. Because of the heating and cooling effects of the circulating drilling mud on the rocks surrounding the borehole, an adjust- ment must be made in the recorded temperatures. Cool rocks in the upper portion of the borehole will be warmed by the circulating mud while the warm rocks in the lower portion will be cooled (Figure 12). For a zone which is sufficiently deep to provide waters hot enough for geothermal purposes, the recorded temperatures will be lower than the undisturbed temperatures. In the Prudhoe Bay Field where the depths of the producing section are between 8,000 and 10,000 feet, the equilibrium temperatures after two or three months are about 25°F (14°C) higher than the temperatures measured immediately after drilling. It is estimated that the equilibrium temperatures in the Nimiuk Point No. 1 and Cape Espenberg No. 1 will be about 18°F (10°C) higher, giving an equilibrium bottomhole temperature of 180°F (82°C) for both test wells (Figures 13 & 14). It should be noted that the geothermal gradients are quite different for the two test wells although the temperatures within the metamorphic rocks at total depth are nearly the same. Insufficient data are available to determine the cause for this anomalous condition. It may indicate that the temperatures are more directly related to the metamorphic "basement" rocks than to absolute depth. The measured and calculated geothermal gradients for the two test wells are given in Figures 13 & 14. The cooling of the rocks by the drilling operations extends to some unknown distance from the borehole. The area immediately adjacent to the borehole would be most affected with the magnitude of the cooling decreasing with the distance from the borehole. The water obtained during the formation tests would have been produced from the rock volume around the wellbore cooled by drilling. Thus, the measured water temperature is lower than what it would be if the formation was allowed to reach equilibrium. Formation Pressures During the formation test in the Nimiuk Point No. 1, discussed above, the tested zone produced about 680 gallons of fluid into the drill string but the fluid did not flow to the surface (Figure 15). The combined flow periods during the formation test were 4 hours and 15 minutes. Testing conditions were not optimum, however, as this was not a production test and the tailpipe perforations were plugged a portion of the time. The calculation of the potentiometric surfaces for the tested zones is given in Figure 15. The pressures are from gauges that were placed in the testing equipment at pertinent depths. The specific gravity and other water quality data was from samples recovered out of the Nimiuk well. The water would come to within 112 feet of the surface. Given that the water from the tested zone will not flow to the surface given the measured formation water density and bottomhole pressure, downhole pumps would have to be utilized to provide the volume of water necessary for district heating, and to bring it to the surface. If 8.87 lbs/gal is assumed for the formation water density in the tested zone of the Cape Espenberg No. 1, the shut-in pressure will produce a potentiometric surface 7694 feet above the tested zone. This is still 424 feet below the surface and in this case pumping would also be required. Reservoir Rocks Although the formations tested did not contain sufficient pressure to provide artesian flow to the surface, it is important that the reservoir potential of the formations be analyzed. It is also important to consider why those particular zones were selected for testing. Those formations tested display considerably better reservoir charac- teristics than the metamorphic rocks encountered in the bottom sections of the two test wells. The metamorphic rocks have very little porosity and permeability, if any at all, except for possible fracturing. At this depth, fracturing would be unpredictable, and it is only remotely possible that fractured rocks in the metamorphic zone could provide a reservoir for this project. Any formation below this level would also lack the high porosity and permeability that is necessary. The regional geology supports the - conclusion that the metamorphic event would have destroyed the reservoir potential of these rocks. An examination of the electrical logs from the Nimiuk Point No. 1 test well does not indicate that the zones selected for testing were actually worthy of testing (Figure 16). Thin beds are Present with slightly greater than normal resistivities which could be interpreted as hydrocarbon-bearing. It is questionable, however, whether potential reservoir rocks are present in these thin zones. The successful formation test (HFT No. 2) for the Cape Espenberg No. 1 test well covered an interval that did not look attractive for recovering fluids during formation testing. The most promising looking reservoir. sec- tion, but not necessarily for hydrocarbons, was much shallower. However, the test of that formation failed when the tailpipe perforations plugged during the test. One tested zone that may have some reservoir potential is only 12 feet thick and, therefore, is not necessarily indicative of the entire section above and below this tested zone. A fourth zone was tested, but it is questionable whether any reservoir rocks are present. It is apparent, therefore, that the formation tests conducted for the pur- poses of locating hydrocarbons did not evaluate the test wells for the purposes of finding large volumes of warm water. It is Probable that zones could be found in these two test wells which could provide greater volumes of water than those zones where successful formation tests were conducted. A moderately large supply of warm water appears to be available in these test wells. Water Chemistry The waters produced during the tests are connate, or ancient, waters which have been present since the time of deposition of the rocks containing the waters. General geologic knowledge of this and similar areas indicates 10 that there is no connection at the present time between the formations tested and the present marine or freshwater systems, The high salinity of the tested waters indicates that such a condition does not exist. This is not a typical geothermal system where surface waters descend along fractures or faults, are heated by the very hot, deep-seated igneous rocks, and are returned to the surface as hot water and/or steam. It is also not a system where the water flows to the surface due to the hydrostatic pressure from more elevated parts of the aquifer. A considerable problem is caused by the presence of high concentrations of total dissolved solids. Analysis of the formation waters from the Nimiuk Point No. 1 revealed 90,000 parts per million (9%) total dissolved solids and 76,263 parts per million (7.6%) NaCl (true) by calculation (Figure 17). Any scheme for production, distribution and disposal of these waters would have to take these conditions into account. DRILLING DEPTHS An important item to be addressed in this report is the drilling depth necessary at Kotzebue in order to encounter large volumes of the warmest water possible. The assumption had been made previously that (1) the Tertiary basin would be continuous throughout the region, (2) at least a moderate depth would be required to obtain the optimum pressures and temper- atures, (3) the hole could be drilled rapidly, (4) a 6000-8000 foot test well would cost between $6 and 8 million using a conventional oi] drilling rig, 3} and (5) the same test well would cost between $1 and 2 million if drilled by a truck mounted rig which is presently unavailable in Alaska. The only serious unanswered problem was to determine the depth required for drilling. The only data publically available for determing the proposed depth was a gravity map prepared by the U.S.G.S. (Figure 18). This map suggests that the depth to basement is considerably less at Kotzebue than it is at Nimiuk Point No. 1. However, it also shows Cape Espenberg No. 1 to be shallower than the Nimiuk Point No. 1 and this is known to be not true. This map was further analyzed by overlaying the gravity map on a map of surface exposures of crystalline rocks. Some areas showed good correlation between the surface crystalline rocks and the gravity interpretation and others clearly did not. It was considered that the gravity response was based both on surface and subsurface occurrence of crystalline rocks and could not be relied upon for this purpose. Seismic data were considered to be the only useful data in determining the depth to true basement at Kotzebue or the depth to correlative points in the Nimiuk Point No. 1. A request was made to Chevron through NANA for the release of sufficient seismic data for this purpose as well as water analyses and other data. Chevron cooperated by releasing their seismic and other data for viewing in San Francisco and provided the geological cross section (Figure 19). Reflection seismic surveys are considered to be the most reliable method of determining the necessary depths. These data clearly refine the previous postulations with respect to a test well at Kotzebue. The equivalent depth to the basement seismic horizon is only 2000 ft. at Kotzebue. Factors that are affected dramatically by the 12 shallow depth are water temperature, test well cost, water availability and continuity of the sedimentary section. All are interrelated to or dependent upon the depth. If the water temperature is taken at the 2000 foot level from either of the two temperature profiles in this report (Figures 13 & 14), it is probable that the temperature selected from the profiles will be lower than the actual temperature which would be encountered at Kotzebue. This will be true if, as stated earlier, the temperature is more closely related to proximity to the marbles and schists than to actual depth. It will not be as warm however, as the bottom hole temperature on the two Chevron test wells. DRILLING COSTS The cost of a test well will be sharply reduced because the shallow depth can be reached with a small rig. A conventional oi1 drilling rig would be uneconomical. A small rig, such as a truck mounted rig, would involve considerably lower mobilization and demobilization costs because of its greatly reduced size and weight. Lower operating costs would also be involved although expendables, such as bits, drilling mud, casing, testing charges, and logging would be the same for either rig. A considerable savings could be achieved in preparing the drilling location as a truck mount rig would require minimal preparation. A shallow sedimentary section would normally possess higher porosities and permeabilities than a deeper, more compacted section. The reservoir fluids 13 would be under less pressure than the deeper section. Whereas a given volume of sedimentary rock at the shallow depth would contain a higher volume of water available for extraction, the lower reservoir pressure would require more time for fluid to be replenished around the bore hole if the produced waters are not reinjected into the system. It is possible, but not probable, that high quality reservoir rocks may not be stratigraphically continuous in this shallow section. This could only be determined by drilling and sustained testing. Figure 11 shows that the older sedimentary section present in Nimiuk Point No. 1 is absent at Kotzebue. 14 CONCLUSIONS These analyses lead to the following conclusions with respect to the availability of geothermal energy at Kotzebue: (1) Wells would be shallow (2,000+feet). (2) Water temperatures would probably be low (105°F to 135°F). (3) Water volumes would probably be adequate. (4) Reinjection of produced water would be necessary. (5) The water would have a lot of dissolved solids. (6) Drilling costs would be low if a small drilling rig such as a truck mounted rig is used. (7) Production rates from wells at Kotzebue could be determined only by sustained flow tests. 15 9L : POINT HOPE \ KIVALINA ° NOATAK BAIRD MOUNTajy, Ss NIMIUK __ eta POINT ee a eae a ) AMBLER KIANA CNOORVIK aN SELAWIK BASIN 9 CKOBUK SHISHMAREF vo” SHUNGNAK OseL awik CAPE _ ~ ESPENBERG a DEERING ° OpuckLAND CANDLE BREVIG MISSION BENDE (EB Ey MARY'S IGLOO Mrs ° @ PILGRIM _HOT HUSLIA SPRINGS o MILES 50 SCALE ©xovuk NOME FIG.| LOCATION MAP-KOTZEBUE AREA wiMiuR\. *o 7> 2 POINT & NO. / Ve 0. Ss Oo U Vo O° . 5 Ll miles } FIG.2 LOCATION MAP-BALDWIN PENINSULA 7 GRAVITY PROFILE Low SURFACE MODERATE DENSITY SEDIMENTARY STRATA HIGH DENSITY BASEMENT ROCKS FIG. 3 GRAVITY SURVEY & PROFILE OVER A DOME WITH A CRYSTALLINE ROCK CORE. HIGH GRAVITY PROFILE Low SURFACE MODERATE DENSITY SEDIMENTARY STRATA | Low DENSITY SALT DOME y FIG. 4 GRAVITY SURVEY OVER A SALT DOME. 18 MAGNETIC PROFILE Low SURFACE LOW SUSCEPTIBILITY ROCK SEDIMENTARY ROCKS LAYERS HIGH SUSCEPTIBILITY BASEMENT ROCKS FIG. 5 MAGNETIC SURVEY & PROFILE OVER A DOME WITH A CRYSTALLINE ROCK CORE. HIGH MAGNETIC PROFILE Low SURFACE MODERATE SUSCEPTIBILITY SEDIMENTA Low noes. DIMENTARY “ havens SUSCEPTIBILITY SALT DOME FIG 6 MAGNETIC SURVEY OVER A SALT DOME 19 ENERGY SOURCE REFLECTING HORIZON @— ENERGY PATH 9 RECEIVING SENSOR THE ENERGY WAVE CREATED BY THE SOURCE TRAVELS DOWNWARD AND 1S REFLECTED UPWARD BY THE REFLECTING HORIZON. THE RETURNING ENERGY WAVE IS RECEIVED BY THE RECEIVING SENSORS. FIG. 7 REFLECTION SEISMOGRAPH SURVEY HORIZONTAL DISTANCE (IN MILES) REFLECTING HORIZONS OEPTH (IN TIME) THE DOWNWARD AND UPWARD TRAVEL TIMES FROM THE REFLECTING HORIZONS ARE RECORDED ALONG THE LINE OF SECTION. THIS CROSS - SECTION SHOWS A DOME IN THE REFLECTING ROCK LAYERS. FIG. 8 SEISMIC RECORD SECTION 20 lz LEGEN: Q Surficial Deposits Ig-i Igneous Intrusives (Plutons) Ig-v Igneous Extrusives (Volcanics) Ss Sediments M Metamorphics S-M Sediments & Metamorphics KOTZEBUE@) FIG. 9 GENERALIZED SURFACE GEOLOGICAL MAP 1000' 2000 3000 4000 5000 6000 FIG.10 NIMIUK POINT NO.1 22 CARBONATES & MARBLE FORMATION. TEST BASE OF PERMAFROST LEGEND CC") _=NO SAMPLES cS ciay SAND & SANDSTONE GRAVEL & CONGLOMERATE GS sCoOAL & -WooD A) —sCVOLcanics SCHIST Beg N B/PF COLUMNAR SECTION 1000° 2000 3000' 4000 5000' 6000' 7000' 8000' vv VV VV VVVVVVV VY wiyvvvy yyy v vw vy¥vVVVYY vvvvvvvuv vvvVVVVYY vv_vvv} Vv v v v v v v vvy viv Vv < < fs < =f <|i< <{<}< << SESS See ccs sss ee cexcc< Sess SSS Scccececec tices Ss sccSSeccccece SeeS Cecceee<< S<<<ecccecs<s S<<evecceccs <<Seseccs S<5e S55 5< SESS SSEES oseeesees Sees << eScese TO 8373 FIG. 11 CAPE ESPENBERG NO.I 23 EMD ° 0 0 Ss Hae B/PF LEGEND NO SAMPLES CLAY SAND & SANDSTONE GRAVEL & CONGLOMERATE COAL & wOoD VOLCANICS SCHIST CARBONATES & MARBLE FORMATION TEST BASE OF PERMAFROST COLUMNAR SECTION INCREASING DEPTH — PERMAFROST WARMED BY DRILLING Bl 5 3 COOLED BY ORILLING teen eee. HH. FREEZING, INCREASING TEMPERATURE —> FIG.12 GENERALIZED TEMPERATURE PROFILE 24 3000 4000: tt 5000 6000 7000 BASE OF oe PERMAFROST 25 GEOTHERMAL GRADIENT: 2.20°F/100' (399°C/KM) MEASURED 2.50°F/ 100' (45.5°C/KM) CALCULATED EQUILIBRIUM aed MECHANICAL PROBLEMS MAXIMUM TEMPERATURE: TEMPERATURE IN °F 159°F (70°C) AT 6210' (TEMP. LOG) 162°F (72°C) AT 6210' (MAX. THERM.) 50 75 100 125 150 175 FIG.13. NIMIUK POINT NO.f TEMPERATURE PROFILE 25 BASE OF woo PERMAFROST 1000 2000 3000 4000 5000 6000 GEOTHERMAL GRADIENT: 1.73°F/100' (315°C/KM) MEASURED 7000 1.94°F/100' (354°C/KM) CALCULATED EQUILIBRIUM “8000 MAXIMUM TEMPERATURE: TEMPERATURE IN °F 163°F (73°C) AT 8115' (TEMP. LOG) 163°F (73° B115' . THERM 9000 (73°C) AT (MAX ) 0 25 50 75 100 125 150 175 FIG. 14. CAPE ESPENBERG NO.| TEMPERATURE PROFILE 26 NIMIUK POINT NO. Ground Level ZONE TESTED 3537-3755 FT MAXIMUM SHUT IN PRESSURE 1552 Psi MAXIMUM FLOW PRESSURE 1252 PS! RECOVERY 1t90OFT ORILLING MUD Tested Z 823 FT MUDDY SALT WATER SS I SS |77FT CLEAR SALT WATER 2190FT TOTAL FLUID FORMATION WATER SPECIFIC GRAVITY 1.065 TOTAL DISSOLVED SOLIDS 90,000 PPM Na Cl (TRUE) 76,263 PPM TEMPERATURE 107 °F CALCULATED RISE OF FORMATION WATER FORMATION PRESSURE 1552 PS!| @3478 FT WATER DENSITY 1.065 x 8.33 LBS/GAL=8.87 LBS/GAL 1552 PSI ————— — ———__—- :3366 FT (8.87 LBS/GAL)(.052 PSI/FT/LB/GAL) GAUGE DEPTH 3478 FT RISE 3366 FT DEPTH BELOW SURFACE 112 FT CAPE ESPENBERG NO. / round Level ' DEPTH TESTED 7918-8128 FT MAXIMUM SHUT IN PRESSURE 3552 LBS MAXIMUM FLOW PRESSURE 3541 LBS RECOVERY 7414 FT MUD & SALT WATER CALCULATED RISE OF FORMATION WATER FORMATION PRESSURE 3552 PS! @ 7694 FT WATER DENSITY (ASSUMED) 8.87 LBS/GAL 3552 PS! (8.87 LBS/GAL)(.052 PSI/FT/LB/GAL) GAUGE DEPTH 8124 FT Tested RISE 7700 FT DEPTH BELOW SURFACE 424 FT =7700FT FIG.I5 FORMATION Uae DATA HIGH PERMEABILITY: conglomerates, sandstones, etc. 3537 a w e o w e z i = = = ° g w z ° N 3750 SPONTANEOUS RESISTIVITY POTENTIAL — 3600 3700 LOW RESISTIVITY: saline formation water 3800 FIG.16 NIMIUK POINT NO. | 28 inc i> 3500 a LOW PERMEABILITY: v4 shales, siltstones, coals, etc. . Yui A DEEP CURVE: reads r tivity of the formation beyond the zone affected by the drilling fluid SHALLOW CURVE: reads stivity of the formation within the zone affected by the drilling fluld separation indicates that the low resistivity formation water.hes been flushed out and replaced by high resistivity drilling fluid ZZ HIGH RESISTIVITY: | hydrocarbons ——~s] (when present) an ELECTRIC LOG Chevron Nimiuk Point No. 1, 544 Ft Above Tool. CRC 33873-4 Sampling Depth (Measured) = 0- 0 Sample No: 3/83 API No: 000000378300 1/13/75 Resistivity 0.085 At 77 Degrees F Specific Gravity 1.085 At 60 Degrees F PH 7.600 At 24 Degrees C TDS(A) 89082 Dissolved Solids By Addition TDS(E) 92150 Dissolved Solids By Evaporation ELEMENT MG/L ION/CL MEG/L I 4, 0.00006617 0.0 BR 0. 0.0 0.0 OH 0. 0.0 0.0 co3 0. 0.0 0.0 HCO3 1220. 0.02306456 20.0 S04 3078. 0.05818925 64.1 CL 52895. 1.00000000 1492.1 NA 27098. 0.51230091 1176.7 CA 1494, 0.02824196 74.5 MG 2624. 0.04960900 215.8 FE 0.71 0. 00001339 0.0 K 512. 0.00967850 13.1 SR 37.11 0.00070158 0.8 BA 0.0 0.0 0.0 SI 31.3 0.00059104 4.5 LI 1.19 0.00002244 0.2 MN 0.80 0. 00001516 0.0 cu 0.03 0.00000064 0.0 AL 0.0 0.0 0.0 NI 80.00 0.00151243 2.7 ZN 5.186 0.00009804 0.2 cs 0.0 0.0 0.0 RB 0.28 0.00000522 0.0 B 0.0 0.0 0.0 PB 0.12 0.00000221 0.0 CR 1.69 0.00003198 0.1 MD 0.2 0.00000379 0.0 Ratio of Anions to Cations = 1.06 FIG. 17 NIMIUK POINT NO. 1 FORMATION WATER CHEMISTRY 29 LEGEND STRUCTURAL LOW STRUCTURAL HIGH KOTZEBUE NP NIMIUK POINT NO.1 CE CAPE ESPENBERG NO.! CONTOUR INTERVAL 20 MILLIGALS ° MILES so SCALE (AFTER BARNES) FIG.18 GRAVITY MAP Le NW SE KOTZEBUE NIMIUK POINT NO.1 KOTZEBUE A HOTHAM SOUND n INLET su SL -2000' -2000' QUATERNARY Seismic @ TERTIARY . CLASTICS -4000' -4000' enn" METAMORPHICS 6000" TD 631! -8000° 1000" (AFTER CHEVRON) 0 MILES : FIG. 19 STRUCTURAL CROSS SECTION FROM KOTZEBUE TO NIMIUK POINT NO.! BIBLIOGRAPHY State of Alaska, Oil and Gas Conservation Committee, Well Completion Report and Log, Nimiuk Point No. 1 Well. State of Alaska, Oil and Gas Conservation Committee, Well Completion Report and Log, Cape Espenberg No. 1 Well. The Standard Oi] Company of California ran the following well logs for the Nimiuk No. 1 and Cape Espenberg No. 1. wells. Dual Induction-Laterolog Temperature Borehole Compensated Sonic Compensated Neutron Formation Density Lithology Eittreim and Others, Isopach Maps, Southern Chukchi Sea, Alaska, Miscellaneous Field Studies Map MF-906, United States Geological Survey. United States Geological Survey Open-File Report 76-70, Bouguer Gravity Map of Alaska. William W. Patton, Jr., and Thomas P. Miller, United States Geological Survey Miscellaneous Geologic Investigations Map I-530, Regional Geologic Map of the Selawik and Southeastern Baird Mountains Quadrangles, Alaska. Helen M. Beikman and Ernest H. Lathram, United States Geological Survey Miscellaneous Field Studies Map MF 789, Preliminary Geologic Map of Northern Alaska, 1976. Barnes, David F, United States Geological Survey Map GP 913, Bouguer Gravity Map of Alaska, 1977. 32 PROPERTY OF: Alaska Power Authority 334 W. 5th Ave, Anchorage, Alaska 99501