High-resolution Temperature Logging Research Articles

Thermal structure of two deep boreholes in the Siljan Ring, Central Sweden, and palaeoclimatic implications

Heat-flow data from deep boreholes are of particular value as a number of factors, including climatic surface temperature variations, may disturb subsurface thermal conditions, especially at shallow depths. This study provides thermal results from two boreholes, Gravberg-1 and Stenberg-1, drilled to large depths in the Siljan Ring impact structure, Baltic Shield, Central Sweden. Taking several high-resolution temperature logs to a depth of more than 5000 m in Gravberg-1 and close to 2000 m in Stenberg-1, and up to a long time after drilling, ensures high-quality deep temperature data. A good-quality thermal conductivity profile was determined from mineralogical composition and radiogenic heat production from a spectral gamma-ray log. The observations show overall thermal conductive profiles with local non-conductive temperature variations. Observed present-day near-surface heat flow (depth range 200–500 m) in Gravberg-1 is 47 mW/m2 (std. dev. 1.5 mW/m2). From observed deep background heat flow, considering heat production, the equivalent steady-state, unperturbed heat flow is estimated at 66–68 mW/m2. Data from Stenberg-1 provide similar results. The observed reduction of heat flow at near-surface level by about 20 mW/m2 is interpreted as originating from long-term palaeoclimatic temperature variations. During the last glacial period, the area was, to varying degree, both ice-free and covered by the Fennoscandian ice sheet. Thermal modelling, with a ground-surface mean-temperature increase by 12±2 °C from glacial to post-glacial time, shows consistency between observed and modelled heat flow perturbations for the full depth range of observations. Heat flow perturbations may be significant to depths of about 2000 m. These results show that, uncorrected for palaeoclimate, depending on depths of measurements, observed continental heat flow values might be markedly underestimated. This applies to Northern Europe and, likely, to many other areas as well.

Deducing flow path mixing by storm-induced bulk chemistry and REE variations in two karst springs: With trends like these who needs anomalies?

Karst aquifers are dynamic hydrologic systems which can be sensitive to short-term recharge events (storms) and heterogeneous recharge characteristics (point recharge at sinks, irregular soil thicknesses). In this study, two adjacent karst springs, Tippery Spring and Near Tippery Spring, were monitored to better understand flow and source mixing characteristics in response to two storms in May and June 2017. Monitoring techniques included high-resolution discharge and temperature logging and collection of spring water using automatic samplers to analyze chemical parameters such as stable water isotopes and Mg/Ca ratios along with Ca/Zr ratios and rare earth elements (REEs) which have had limited testing in karst systems. The two springs exhibited behaviors which were both unique to each spring and shared depending on which parameter is considered. Spring-specific behaviors included discharge and isotopic response, with Tippery Spring having a flashier and faster conduit flow behavior relative to Near Tippery Spring’s delayed storm response. Absolute Mg/Ca values were spring-specific, owing to the relative fraction of limestone and dolostone in their respective recharge areas, although both springs showed similar Mg/Ca ratio shifts after storms. While Ca/Zr ratios changed in timing and intensity with storm intensity, both springs exhibited a decline in Ca/Zr ratios as calcium-rich carbonate matrix water was displaced by zirconium-rich storm recharge water from sinking streams off the clastic upland ridges. Flushing of recharged storm water resulted in an increase in total REE concentrations at both springs (from <0.15 ppb to >1.0 ppb), with the timing and magnitude of concentration increases determined by the degree of surface connectivity intrinsic to each spring and the intensity of the recharge event. REEs and Ca/Zr ratios provided additional and complementary tracer techniques to better understand transient recharge and flow behaviors in karst springs.

Borehole Heat Budget Calculator: A New Tool for the Quick Exploitation of High-Resolution Temperature Profiles by Hydrogeologists

Distributed temperature sensing is known to provide sharp signals which are very efficient for mapping hydraulically active fractures in wellbores. High-resolution temperature sensing has specifically demonstrated its capacity to characterize very low flows in wellbores. But as sharp as they can be, temperature profiles are often difficult to decipher. The aim of the present work is to provide and to test the “Borehole Heat Budget Calculator” (BHB Calculator), which is implemented as a fast and easy to use tool for the quantitative analysis of depth-temperature profiles. The Calculator is suitable for most pumping and draining configurations, as the heat budget is generalized for modelling multidirectional flow systems within the same wellbore. The formatted worksheet allows the quick exploitation of temperature logs, and is applicable for the characterization of distributed fractures in long screened wellbores. Objectives of the heat modelling are to enhance the readability of complex depth-temperature data, as well as to quantify distribution of inflow intensities and temperatures with depth. The use of heat budget helps to clearly visualize how heat conduction and heat advection contributions are distributed along wellbores profiles. Calculations of inflow temperatures and their evolution through pumping duration is a prerequisite to infer about the nature of aquifer properties (i.e. conduits, distributed or discrete fractures, porous media), as well as to give insight information about the mapping of effective flow paths draining the aquifer. The efficiency and limitations of the BHB Calculator are being tested through high-resolution temperature logging, along with complementary flowmetering and televiewing logging in fractured aquifers located in the St-Lawrence Lowlands, Quebec, Canada.

High-Resolution Wellbore Temperature Logging Combined with a Borehole-Scale Heat Budget: Conceptual and Analytical Approaches to Characterize Hydraulically Active Fractures and Groundwater Origin

This work aims to provide an overview of the thermal processes that shape wellbore temperature profiles under static and dynamic conditions. Understanding of the respective influences of advection and conduction heat fluxes is improved through the use of a new heat budget at the borehole scale. Keeping in mind the thermal processes involved, a qualitative interpretation of the temperature profiles allows the occurrence, the position, and the origin of groundwater flowing into wellbores from hydraulically active fractures to be constrained. With the use of a heat budget developed at the borehole scale, temperature logging efficiency has been quantitatively enhanced and allows inflow temperatures to be calculated through the simultaneous use of a flowmeter. Under certain hydraulic or pumping conditions, both inflow intensities and associated temperatures can also be directly modelled from temperature data and the use of the heat budget. Theoretical and applied examples of the heat budget application are provided. Applied examples are shown using high-resolution temperature logging, spinner flow metering, and televiewing for three wells installed in fractured bedrock aquifers in the St-Lawrence Lowlands, Quebec, Canada. Through relatively rapid manipulations, thermal measurements in such cases can be used to detect the intervals or discrete positions of hydraulically active fractures in wellbores, as well as the existence of ambient flows with a high degree of sensitivity, even at very low flows. Heat budget calculations at the borehole scale during pumping indicate that heat advection fluxes rapidly dominate over heat conduction fluxes with the borehole wall. The full characterization of inflow intensities provides information about the distribution of hydraulic properties with depth. The full knowledge of inflow temperatures indicates horizons that are drained from within the aquifer, providing advantageous information on the depth from which groundwater originates during pumping.

Skeletal microstructure and stable isotope signature of three bathyal solitary cold-water corals from the Azores

Skeletons of cold-water corals are potential geochemical archives that record oceanographic parameters, such as bottom water temperature in the deep sea. In this study, the three solitary scleractinian species, Caryophyllia cyathus, Desmophyllum cristagalli and Stenocyathus vermiformis, were sampled from upper bathyal 500m water depths in the southern Faial Channel (Azores archipelago). The stable carbon isotope (δ13C) and oxygen isotope (δ18O) compositions of the corals were analysed and related to their skeletal architecture. Background data, including data from high-resolution temperature logs and on the ambient seawater isotopic composition, were compared with δ18O-based temperature reconstructions to test the suitability of these cold-water corals as geochemical archives and to explore the role of vital effects on skeletal geochemistry. Although all of the corals experienced identical and near-stable salinities and temperatures, the stable isotopic signatures vary within and among species. Both δ13C and δ18O values fluctuate in relation to growth bandings and are therefore most likely dependent on calcification rates and associated kinetic vital effects. The studied specimens are 13C depleted with respect to equilibrium with ambient seawater, indicating significant uptake of respired CO2 by their skeletons. Skeletal δ18O values vary by up to 3.6‰ among the growth bands of one of the coral specimens, translating into an unrealistic reconstructed temperature amplitude of ~16°C. This contrasts with the minute intra-annual amplitude of the stable temperature regime (annual mean 12.30±0.25°C). Nevertheless, δ13C vs. δ18O regression lines can be used to deduce ambient temperatures by applying the lines technique (Smith et al., 2000; Palaios 15, 25–32), which yields temperatures that coincide with the measured maximum temperature range in the case of D. cristagalli and for most C. cyathus samples, but deviate by 2.95°C from the measured annual mean in the case of the S. vermiformis specimen.

Time-dependent thermal state of the lithosphere in the foreland of the Eastern Carpathians bend. Insights from new geothermal measurements and modelling results

SUMMARY The time-dependent heat budget, thermal evolution and rheology of the lithosphere in the last 13Myr, along a 120 km long profile in the foreland of the Eastern Carpathians bend is presented. The study area, a complex tectonic environment in the vicinity of the wellknown intermediate-depth seismogenic Vrancea zone, includes the deepest sedimentary basin in Romania (∼18 km), with a recent rapid evolution in the last 13Myr (8 km of sediments). Detailed high-resolution temperature logs in the depth ranges from 0‐700 m to 0‐2400 m in eight thermally stabilized boreholes, together with logging and geological information on structure, lithology and time evolution of the sedimentary pile have been used to model the thermal evolution by means of a 2-D finite element model which includes sedimentation history, sediment compaction, lateral and vertical variation of thermal properties of sediments and consolidated crust. Modelling results have been compared to measured temperatures, corrected for palaeoclimate effects, in a trial and error iterative approach. Sedimentation, palaeoclimate, undercompaction and heat refraction effects on one hand, and the heat generated in the upper crust, on the other, combine to explain the observed subsurface temperature field and in particular the pronounced curvature of the vertical temperature profiles. The Neogene-Quaternary sedimentation resulted in a rather uniform deficit of the surface heat flux of about 12 mW m −2 in the study area, in spite of the marked lateral variation of the sedimentary pile thickness. The palaeoclimate effect is responsible for a surface heat flux depression of 7‐8 mW m −2 , uniform along the study profile. Unlike older sedimentary basins, in the study area transient sedimentation thermal effects add to palaeoclimate effects in establishing the temperature field in the depth range of geothermal measurements. The lateral variation of the palaeoclimatically corrected surface heat flux from the centre of the Focsani Depression (40 mW m −2 ) to its margin and the foreland platform (70 mW m −2 ) is mainly the result of the lateral variation of the heat produced in the upper crust where thickness varies from 7 to 21 km, respectively. A heat production of 2.3 µ Wm −3 for the southeastern end of the profile and of 2.15 µ Wm −3 for the rest of it has been modelled. As a result of the sedimentation process, temperature variations as large as 70‐100 ◦ C occurred in the pre-Neogene sediments and the crystalline crust immediately under the sedimentary pile, with consequences on the metamorphic state and rheological behaviour of the foreland

On the geothermal regime of the foreland of the Eastern Carpathians bend

Detailed high resolution temperature logs were obtained in 41 thermally stabilized boreholes in the Eastern Carpathians bend and its foreland. The investigated depth ranges from 0–500 to 0–2500 m. The temperature logs show (a) a wide range of geothermal gradients, from as low as 23 mK m −1 (foredeep), to 37 and 53 mK m −1 at the external limit of the foredeep and on the foreland platform, and (b) a second-order feature, namely a curvature indicating a general increase of the gradient with depth. The new temperature data are discussed in terms of thermal effects of sedimentation, palaeoclimate changes of the Earth's surface temperature, and fluid flow, which contribute to the observed curvature of temperature profiles in the investigated depth interval. The discussion is illustrated with data concerning two of the deepest logged boreholes and a profile through the centre of the foredeep basin.

Heat transfer by free convection from an isothermal vertical round plate in unlimited space

Three high resolution temperature logs recorded after shut-in of the main borehole KTB-Oberpfalz HB of the German Continental Deep Drilling Program are used to determine a first estimate of the undisturbed formation temperature, using the line source model of Bullard [Bullard, E.C., 1947. The time necessary for a borehole to attain temperature equilibrium. Monthly Notices Royal Astronomical Society, Geophysical Supplement 5, 127–130.]. The resulting formation temperature profile and the corresponding temperature gradient, deviate from previous estimates [Wilhelm, H., Baumann, C., Zoth, G., 1995. Some results of temperature measurements in the KTB main borehole, Germany. Geothermics 24, 101–113; Clauser, C., Giese, P., Huenges, E., Kohl, T., Lehmann, H., Rybach, L., Safanda, J., Wilhelm, H., Windloff, K., Zoth, G., 1997. The thermal regime of the crystalline continental crust: implications from the KTB. Journal Geophysical Research 102, 18,417–18,441; Wilhelm, H., 1998. Comparison of predicted and logged temperatures in the KTB main hole. In: Popov, Yu, Pimenov, V. (Eds.), Proc. Int. Conf. The Earth’s Thermal Field and Related Research Methods. Moscow State Geological Prospecting Academy, Moskow, pp. 280–281], which were derived from bottomhole measurements and from multiple temperature logs recorded during drilling pauses at 4500, 6000 and 7200 m depth. Although the database is not large enough to allow a formal error estimate, the noise in the extrapolated formation temperature indicates a mean error of about ±0.15 K between 2500 and 5200 m depth and a mean error of ±0.5 K below 5200 m depth.

Undisturbed temperature in the main drillhole of the German Continental Deep Drilling Program predicted from temperature logs recorded after shut-in

Three high resolution temperature logs recorded after shut-in of the main borehole KTB-Oberpfalz HB of the German Continental Deep Drilling Program are used to determine a first estimate of the undisturbed formation temperature, using the line source model of Bullard [Bullard, E.C., 1947. The time necessary for a borehole to attain temperature equilibrium. Monthly Notices Royal Astronomical Society, Geophysical Supplement 5, 127–130.]. The resulting formation temperature profile and the corresponding temperature gradient, deviate from previous estimates [Wilhelm, H., Baumann, C., Zoth, G., 1995. Some results of temperature measurements in the KTB main borehole, Germany. Geothermics 24, 101–113; Clauser, C., Giese, P., Huenges, E., Kohl, T., Lehmann, H., Rybach, L., Safanda, J., Wilhelm, H., Windloff, K., Zoth, G., 1997. The thermal regime of the crystalline continental crust: implications from the KTB. Journal Geophysical Research 102, 18,417–18,441; Wilhelm, H., 1998. Comparison of predicted and logged temperatures in the KTB main hole. In: Popov, Yu, Pimenov, V. (Eds.), Proc. Int. Conf. The Earth’s Thermal Field and Related Research Methods. Moscow State Geological Prospecting Academy, Moskow, pp. 280–281], which were derived from bottomhole measurements and from multiple temperature logs recorded during drilling pauses at 4500, 6000 and 7200 m depth. Although the database is not large enough to allow a formal error estimate, the noise in the extrapolated formation temperature indicates a mean error of about ±0.15 K between 2500 and 5200 m depth and a mean error of ±0.5 K below 5200 m depth.

Hydrochemical and isotopic characterisation of the Bathonian and Bajocian coastal aquifer of the Caen area (northern France)

This paper describes the geochemical evolution of groundwater in the Bathonian and Bajocian aquifer along its flowpath. Since this aquifer represents one of the main sources of fresh water supply in the Caen area and has been subjected to a Holocene marine intrusion, its management requires a sound knowledge of (1) the primary conditions and (2) the potential influence of either natural or anthropogenic pressures. Groundwater vertical sampling validity is discussed with the contribution of high resolution temperature logging. The main processes of geochemical evolution along a groundwater flow line and the sea-water intrusion characteristics are discussed using ionic concentrations (Br −, F − and major elements) and isotopes (water δ 2H and δ 18O, TDIC δ 13C and A 14C, sulphate δ 18O and δ 34S). As the 13C content of TDIC is used as a tracer of water-rock interaction, it shows evidence of specific chemical and isotopic evolutions of groundwater within the aquifer, both related to water-rock interaction and mineral equilibria in groundwater. All the above-mentioned tracers evolve downflow: cation concentrations are modified by exchange with clay minerals allowing a high F − concentration in groundwater, whereas Br − and SO 2− 4 concentrations appear to be redox condition dependant. Superimposed on these geochemical patterns, δ 18O and δ 2H compositions indicate that aquifer recharge has varied significantly through time. The chemical evolution of groundwater is locally affected by a salty water intrusion that is characterised by mixing between Flandrian fresh water and sea-water which has interacted with peat as evidenced by a high Br −/Cl − ratio and SO 2− 4 reduction.

Geothermal reconnaissance of the Marmara Sea region (NW Turkey): surface heat flow density in an area of active continental extension

Northwestern Anatolia is an area of significant neotectonic activity. The Northern Anatolian Fault splits into different branches and the tectonic regime changes from translation to a combination of extension and translation. High seismicity as well as frequent and in places large hot springs are related to these tectonic features. The present study aims at characterising the geothermal situation of this area by detailed heat flow density mapping and thermal spring studies. High-resolution temperature logs and measurements of rock thermal conductivity were used to determine the terrestrial heat flow density. Because of the shallowness of the available drillholes (maximum depth of 200 m), hydraulic influences on the thermal profiles had to be taken into account. Conductive heat flow density was calculated considering possible convective effects due to vertical water movements. In spite of these hydraulic influences, the temperature distribution showed stability over a time period of at least one year. Stationary models could therefore be applied. Terrestrial surface heat flow density varies regionally from 35 to 115 mW/m 2, with a mean value of 60 mW/m 2. The heat flow density map shows that the extensional tectonics of the region south of the Marmara Sea is characterised by higher heat flow density values. Regions with low tectonic activity such as parts of European Turkey or regions with compressional and translational tectonics have average or slightly lower values. The spatial pattern of thermal springs in the Marmara Sea region does not coincide with the terrestrial heat flow density distribution. Their appearance is bound to neotectonic faults (= locally enhanced vertical permeabilities).

High-resolution temperature logging in shallow drillholes for the determination of terrestrial heat flow: field examples and analysis

The first 200 m of the Earth's crust is the depth range most investigated by drilling. Temperature profiles in such shallow drillholes generally show severe influences of groundwater flow; therefore they are rarely used for heat flow determinations. But regardless how severely the temperature logs are influenced by advective heat transfer the “background” conductive heat flow signal is still present in the data. It is shown how to handle distorted temperature profiles by means of simple one-dimensional, steady-state models. The undisturbed (“background”) heat flow is estimated by model calculations; the comparison of the modelled temperature profiles with the measured logs is a test for the credibility of the modelling approach. Examples from northwestern Switzerland and northwestern Turkey with irregular temperature profiles are given for the following situations: conductive-convective regime with vertical groundwater movement over the entire observation depth; vertical flow in a certain layer located between purely conductive layers; and water flow inside of the drillhole. Measured temperature profiles can be approximated by modelling within ±0.2°C. Repeated, high-precision digital temperature logging is needed to prove the temporal stability of the convective disturbances in order to use steady-state models.

High-resolution digital temperature logging in areas with significant convective heat transfer : M. Pfister & L. Rybach, Geothermics, 24(1), 1995, pp 95–100

High-resolution digital temperature logging in areas with significant convective heat transfer : M. Pfister & L. Rybach, Geothermics, 24(1), 1995, pp 95–100

High-resolution digital temperature logging in areas with significant convective heat transfer

The Marmara region of northwestern Turkey is characterized by frequent manifestations of anomalously high temperature gradients in the underground, thermal springs, and steaming grounds. Within an interdisciplinary project, our research group measured temperature profiles in many drillholes in this region, using a digital temperature logging tool. Temperatures are measured by a PT 100 sensor; the 2 km wireline and its winch are mounted on a trailer; the data acquisition system is freely movable, weighs about 40 kg, and is transported by jeep along with a 4.7 kW power generator. This system consists of a controlling unit for the winch drive, a high-precision electrical resistance meter with a sensitivity of 100 ppm Ω and a 286 MS-DOS PC as the recording unit. All parts of the equipment are commercially available. The depth interval between two measurements is 10 cm and maximumlogging speed is 5 m/min. Using this temperature tool we were able to detect convection cells in a borehole in northern Switzerland. These cells, about 1 m in length, have a temperature amplitude range of about 0.01–0.04°C. Repeated measurements of boreholes in Switzerland and in northwestern Turkey show, for the entire length of the wells, a maximum difference of 0.05–0.1°C. The measured temperature profiles show different distortions (nonlinearity) as a result of the strong influence of groundwater circulation. The observations are checked for constancy in time (repeated measurements after one year). Using different models of groundwater movement, local heat flow can be calculated even from such disturbed temperature logs. These models are presented and discussed with respect to their reliability.

High-resolution digital temperature logging in areas with significant convective heat transfer

High-resolution digital temperature logging in areas with significant convective heat transfer

Heat flow and subsurface temperature as evidence for basin-scale ground-water flow, North Slope of Alaska

Research Article| May 01, 1992 Heat flow and subsurface temperature as evidence for basin-scale ground-water flow, North Slope of Alaska DAVID DEMING; DAVID DEMING 1U.S. Geological Survey, 345 Middlefield Road, M.S 923, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar JOHN H. SASS; JOHN H. SASS 2U.S. Geological Survey, 2255 North Gemini Drive, Flagstaff, Arizona 86001 Search for other works by this author on: GSW Google Scholar ARTHUR H. LACHENBRUCH; ARTHUR H. LACHENBRUCH 1U.S. Geological Survey, 345 Middlefield Road, M.S 923, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar ROBERT F. DE RITO ROBERT F. DE RITO 1U.S. Geological Survey, 345 Middlefield Road, M.S 923, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1992) 104 (5): 528–542. https://doi.org/10.1130/0016-7606(1992)104<0528:HFASTA>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation DAVID DEMING, JOHN H. SASS, ARTHUR H. LACHENBRUCH, ROBERT F. DE RITO; Heat flow and subsurface temperature as evidence for basin-scale ground-water flow, North Slope of Alaska. GSA Bulletin 1992;; 104 (5): 528–542. doi: https://doi.org/10.1130/0016-7606(1992)104<0528:HFASTA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract In conjunction with the U.S. Geological Survey's exploration program in the National Petroleum Reserve, Alaska (NPRA) several high-resolution temperature logs were made in each of 21 drillholes between 1977 and 1984. These time-series of shallow (average 600-m depth) temperature profiles were extrapolated to infinite time to yield equilibrium temperature profiles (±0.1 °C). Thermal gradients are inversely correlated with elevation, and vary from 22 °C/km in the foothills of the Brooks Range to as high as 53 °C/km on the coastal plain to the north. Shallow temperature data were supplemented with 24 equilibrium temperatures (±3-5 °C) estimated from series of bottom-hole temperatures (BHTs) measured near the bottom of petroleum exploration wells. A total of 601 thermal conductivity measurements were made on drill cuttings and cores. Near-surface heat flow (±20%) is inversely correlated with elevation and ranges from a low of 27 mW/m2 in the foothills of the Brooks Range in the south, to a high of 90 mW/m2 near the north coast. Subsurface temperatures and thermal gradients estimated from corrected BHTs are similarly much higher on the coastal plain than in the foothills province to the south. Significant east-west variation in heat flow and subsurface temperature is also observed; higher heat flow and temperature coincide with higher basement topography. The observed thermal pattern is consistent with forced convection by a topographically driven ground-water flow system; alternative explanations are largely unsatisfactory. Average ground-water (Darcy) velocity in the postulated flow system is estimated to be of the order of 0.1 m/yr; the effective basin-scale permeability is estimated to be of the order of 10-14 m2. Organic maturation data collected in other studies indicate that systematic variations in thermal state may have persisted for tens of millions of years. The ground-water flow system thought to be responsible for present heat-flow variations conceivably has existed for the same period of time, possibly providing the driving mechanism for petroleum migration and accumulation at Prudhoe Bay. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.