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1.
James T. Mickam Benjamin S. Levy George W. Lee Jr. 《Ground Water Monitoring & Remediation》1984,4(4):167-171
Ground water flow in karst terranes generally occurs in the solution channels of carbonate aquifers. A hydrogeologist may utilize borehole geophysical methods to identify these solution channels in aquifers. Two specific methods that are applicable in karst terrains are:
1. Natural gamma ray logging
2. Borehole caliper logging.
Gamma ray logging can detect the presence of inter-bedded strata in the main limestone unit, such as shale, which emit high levels of gamma radiation. Gamma ray logging can also detect clay deposits in solution channels that may act to restrict the flow of ground water. The areal extent of these rock strata or clay-filled solution channels can be determined when gamma ray logs are conducted at several borehole locations across the site of investigation.
Borehole caliper logging can be employed to determine the presences of solution channels within the aquifer when penetrated by a borehole. In addition, since shale layers and clay filling are less resistant than the surrounding limestone, the caliper log may detect both the presence and the thickness of shale or clay layers in the aquifer.
Gamma ray logs can be used in conjunction with caliper logs to provide data on the stratigraphic location and thickness of solution channels and clay and shale layers within a limestone aquifer. This information is valuable to the hydrogeologist performing investigations at sites located in limestone terranes because ground water flow preferentially occurs along solution channels. 相似文献
1. Natural gamma ray logging
2. Borehole caliper logging.
Gamma ray logging can detect the presence of inter-bedded strata in the main limestone unit, such as shale, which emit high levels of gamma radiation. Gamma ray logging can also detect clay deposits in solution channels that may act to restrict the flow of ground water. The areal extent of these rock strata or clay-filled solution channels can be determined when gamma ray logs are conducted at several borehole locations across the site of investigation.
Borehole caliper logging can be employed to determine the presences of solution channels within the aquifer when penetrated by a borehole. In addition, since shale layers and clay filling are less resistant than the surrounding limestone, the caliper log may detect both the presence and the thickness of shale or clay layers in the aquifer.
Gamma ray logs can be used in conjunction with caliper logs to provide data on the stratigraphic location and thickness of solution channels and clay and shale layers within a limestone aquifer. This information is valuable to the hydrogeologist performing investigations at sites located in limestone terranes because ground water flow preferentially occurs along solution channels. 相似文献
2.
Signatures in flowing fluid electric conductivity logs 总被引：1，自引：0，他引：1
Flowing fluid electric conductivity logging provides a means to determine hydrologic properties of fractures, fracture zones, or other permeable layers intersecting a borehole in saturated rock. The method involves analyzing the time-evolution of fluid electric conductivity (FEC) logs obtained while the well is being pumped and yields information on the location, hydraulic transmissivity, and salinity of permeable layers. The original analysis method was restricted to the case in which flows from the permeable layers or fractures were directed into the borehole (inflow). Recently, the method was adapted to permit treatment of both inflow and outflow, including analysis of natural regional flow in the permeable layer. A numerical model simulates flow and transport in the wellbore during flowing FEC logging, and fracture properties are determined by optimizing the match between simulation results and observed FEC logs. This can be a laborious trial-and-error procedure, especially when both inflow and outflow points are present. Improved analyses methods are needed. One possible tactic would be to develop an automated inverse method, but this paper takes a more elementary approach and focuses on identifying the signatures that various inflow and outflow features create in flowing FEC logs. The physical insight obtained provides a basis for more efficient analysis of these logs, both for the present trial and error approach and for a potential future automated inverse approach. Inflow points produce distinctive signatures in the FEC logs themselves, enabling the determination of location, inflow rate, and ion concentration. Identifying outflow locations and flow rates typically requires a more complicated integral method, which is also presented in this paper. 相似文献
3.
Stefanie A. Crisman Fred. J. Molz David L. Dunn Frank C. Sappington 《Ground Water Monitoring & Remediation》2001,21(4):96-100
It is increasingly common for the electromagnetic borehole flowmeter (EBF) to he used to measure hydraulic conductivity (K) distributions in subsurface flow systems. Past applications involving the EBF have been made mostly in confined aquifers (Kabala 1994; Boman et al. 1997; Podgorney and Ritzi 1997; Ruud and Kabala 1997a, 1997b; Flach et al. 2000), and it has been common to set up a flow field around a test well using a small pump that is located near the top of the well screen (Mob, and Young 1993). In thin, unconfined aquifers that exhibit ground water tables near the ground surface and that undergo drawdown during pumping, such a configuration can be problematical because pumping and associated drawdown may effectively isolate the upper portion of the aquifer from the flowmeter. In these instances, a steady-state flow field in the vicinity of the test well may be created using injection rather than pumping, allowing for testing in the otherwise isolated upper portion of the aquifer located near the initial water table position. Using procedures developed by Molz and Young (1993), which were modified for an injection mode application, testing was conducted to determine whether or not the injection mode would provide useful information in a shallow, unconfined aquifer that required the collection of data near the initial water table position. Results indicated that the injection mode for the EBF was well suited for this objective. 相似文献
4.
5.
Geophysical well logging has been applied for fracture characterization in crystalline terrains by physical properties measurements and borehole wall imaging. Some of these methods can be applied to monitor pumping tests to identify fractures contributing to groundwater flow and, with this, determine hydraulic conductivity and transmissivity along the well. We present a procedure to identify fractures contributing to groundwater flow using spontaneous potential measurements generated by electrokinetic processes when the borehole water head is lowered and then monitored while recovering. The electrokinetic model for flow through a tabular gap is used to interpret the measured data and determine the water head difference that drives the flow through the fracture. We present preliminary results at a test site in crystalline rocks on the campus of the University of São Paulo. 相似文献
6.
Identifying flows into, out of, and across boreholes is important for characterizing aquifers, determining the depth at which water enters boreholes, and determining the locations and rates of outflow. This study demonstrates how Single Borehole Dilution Tests (SBDTs) carried out under natural head conditions provide a simple and cheap method of identifying vertical flow within boreholes and determining the location of in‐flowing, out‐flowing, and cross‐flowing fractures. Computer simulations were used to investigate the patterns in tracer profiles that arise from different combinations of flows. Field tracer tests were carried out using emplacements of a saline tracer throughout the saturated length of boreholes and also point emplacements at specific horizons. Results demonstrated that SBDTs can be used to identify flowing fractures at the top and bottom of sections of vertical flow, where there is a change in vertical flow rate within a borehole, and also where there are consistent decreases in tracer concentration at a particular depth. The technique enables identification of fractures that might be undetected by temperature and electrical conductance logging, and is a simple field test that can be carried out without pumping the borehole. 相似文献
7.
Deep observation boreholes in the vicinity of active production wells in Honolulu, Hawaii, exhibit the anomalous condition that fluid-column electrical conductivity logs and apparent profiles of pore-water electrical conductivity derived from induction conductivity logs are nearly identical if a formation factor of 12.5 is assumed. This condition is documented in three boreholes where fluid-column logs clearly indicate the presence of strong borehole flow induced by withdrawal from partially penetrating water-supply wells. This result appears to contradict the basic principles of conductivity-log interpretation. Flow conditions in one of these boreholes was investigated in detail by obtaining flow profiles under two water production conditions using the electromagnetic flowmeter. The flow-log interpretation demonstrates that the fluid-column log resembles the induction log because the amount of inflow to the borehole increases systematically upward through the transition zone between deeper salt water and shallower fresh water. This condition allows the properties of the fluid column to approximate the properties of water entering the borehole as soon as the upflow stream encounters that producing zone. Because this condition occurs in all three boreholes investigated, the similarity of induction and fluid-column logs is probably not a coincidence, and may relate to aquifer response under the influence of pumping from production wells. 相似文献
8.
A suction side sample collector (SSSC) is a contrivance installed hydraulically ahead of the intake port of a pumping device. This paper describes construction and operational details of SSSCs fitted to a submersible pump with packer for use in a 6-inch cased borehole, an air lift pump with packer for use in a 1-inch or 2.5-inch cased borehole, a bladder pump for use in a casing of 2-inch or greater diameter, and a jet pump with packer for use in a 2-inch cased borehole.
Each form of SSSC has been thoroughly tested in ground water quality sampling for volatile organic chemicals. Comparative data for samples collected with the SSSCs and conventional sample collecting gear are presented. The SSSC is demonstrated to be superior to other methods of collecting volatile organic chemical samples owing to its freedom from contamination by the pump delivery line and to its mode of collecting the sample from a position in the well remote from disturbance by the pumping technique.
SSSCs are conveniently decontaminated, easily transported, and can be used to deliver samples to the laboratory while still at formation pressure. The air-lift pumps, described in this paper for use with SSSCs in 1- and 2.5-inch casings, have pumping capacities greater than obtained by other methods that can operate in these small casings. Discharge rates of up to 2 gpm are routinely achieved with the 1-inch model and higher rates are common With the 2.5-inch model. The use of packers with these pumps reduces the time needed to replace the water in the casing with fresh water from the formation. 相似文献
Each form of SSSC has been thoroughly tested in ground water quality sampling for volatile organic chemicals. Comparative data for samples collected with the SSSCs and conventional sample collecting gear are presented. The SSSC is demonstrated to be superior to other methods of collecting volatile organic chemical samples owing to its freedom from contamination by the pump delivery line and to its mode of collecting the sample from a position in the well remote from disturbance by the pumping technique.
SSSCs are conveniently decontaminated, easily transported, and can be used to deliver samples to the laboratory while still at formation pressure. The air-lift pumps, described in this paper for use with SSSCs in 1- and 2.5-inch casings, have pumping capacities greater than obtained by other methods that can operate in these small casings. Discharge rates of up to 2 gpm are routinely achieved with the 1-inch model and higher rates are common With the 2.5-inch model. The use of packers with these pumps reduces the time needed to replace the water in the casing with fresh water from the formation. 相似文献
9.
INFLUENCE OF PUMPING ON FOUR-COMPONENT BOREHOLE STRAIN AT TAI'AN SEISMIC STATION AND ITS INTERFERENCE MECHANISM 
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下载免费PDF全文 JIA Yuan GAN Wei-jun LI Jie ZHU Cheng-lin YIN Hai-tao LU Shuang-ling JU Jia-bin 《地震地质》2019,41(6):1429-1443
Four-component borehole strainmeter (FCBS) is one kind of high-precision borehole strain observation instruments invented in China. As a kind of near-surface deformation observation instrument, FCBS is also easily disturbed by the external environment factors. As a common factor, pumping has significant influence on FCBS observation. Existing studies mostly identify the pumping interference from the perspective of observation curve morphology, relatively few studies focus on its interference mechanism. In order to truly capture earthquake precursor information, it is necessary to study the interference mechanism. In recent years, RZB-3 type FCBS at Tai'an seismic station has been seriously affected by pumping, so it is necessary and also feasible to study the interference mechanism of pumping. Since the influence of pumping interference on borehole strainmeter is common, this work would be very practical and be used for reference by other borehole strain observation stations.
We find that the original observation curves and observed surface strain, shear strain from RZB-3 type FCBS at Tai'an seismic station have the characteristics of synchronous change with the borehole water level, in which the linear correlation coefficient between the two observed shear strain curves and borehole water level reached 0.70 and 0.82 respectively. We further find that the principal strain direction of borehole and borehole water level after normalization meet the nonlinear function as y=1.217arctan(x)0.224-0.284. The above phenomenon indicates that the observation of RZB-3 type FCBS at Tai'an seismic station is significantly affected by the borehole water level, and the influence is more obvious and the gradient is larger at the stage of low water level. Pumping interference often appears in low water level stage and changes the rock pore pressure state. Statistics show that pumping interference affects the borehole strain state.
To investigate the interference mechanism of pumping to RZB-3 type FCBS at Tai'an seismic station, we take a known pumping as an example, in which we study the principal strain state of the borehole in three periods of normal pumping, interruption of pumping and resuming pumping respectively. During each period, we solve 3 parameters of the principal plane strain state, i.e. the maximum principal strain rate, the minimum principal strain rate and the maximum principal strain direction from four observation equations of FCBS by nonlinear iterative least squares algorithm. On the other hand, concentrated load model (CLM) is used to simulate the mechanical mechanism of pumping. Firstly, the depth of FCBS relative to pumping source and the concentrated load at pumping source are inversed, then, the strain state surrounding the pumping well, including the state at RZB-3 borehole, is simulated by forward modeling. By comparing these results, we find that:
(1)The concentrated load at pumping source inversed by CLM during periods of normal pumping and resuming pumping are both located at or near the bottom of the pumping well, which is consistent with the actual situation, indicating that mechanism and degree of the influence of pumping on borehole strain are well simulated by CLM.
(2)The observed strain state is consistent with the simulation result of pumping interference by forward modeling, indicating that the principal strain state of borehole calculated based on observation of FCBS reflects the true strain state of borehole under different pumping states.(3)The inversed concentrated load at pumping source during pumping periods is significant greater than the load of the pumped water, indicating that the pumping process has more significant influence on the pore pressure of rocks than the load of the pumped water.
Even though CLM is an approximate simulation since it's based on some elastic assumptions, the interference mechanism of pumping on RZB-3 type FCBS at Tai'an seismic station is well explained, which is maybe very helpful for studying the influence of pumping interference on other deformation instruments, locating the unknown pumping source and studying the characteristics of pore pressure of rocks. 相似文献
10.
Depth-discrete aquifer in formal ion was obtained using recently developed adaptations and improvements to conventional characterization techniques. These improvements included running neutron porosity and hulk density geophysical logging tools through a cased hole, performing an enhanced point-dilution tracer test for monitoring tracer concentration as a function of Lime and depth, and using pressure derivatives for diagnostic and quantitative analysis of constant rate discharge lest data. Data results from the use of these techniques were used to develop a conceptual model of a heterogeneous aquifer. Depth-discrete aquifer information was required to effectively design field-scale deployment and monitoring of an in situ bioremediation technology.
Geophysical logging and point-dilution tracer test results provided the relative distribution of porosity and horizontal hydraulic conductivity, respectively, with depth and correlated well. Hydraulic pumping tests were conducted to estimate mean values for transmissivity and effective hydraulic conductivity, Tracer lest and geophysical logging results indicated that ground water flow was predominant in the upper approximate 10 feet of the aquifer investigated. These results were used to delineate a more representative interval thickness for estimating effective hydraulic conductivity. Hydraulic conductivity, calculated using this representative interval, was estimated lo be 73 ft/d, approximately three limes higher than that calculated using the full length of the screened test interval. 相似文献
Geophysical logging and point-dilution tracer test results provided the relative distribution of porosity and horizontal hydraulic conductivity, respectively, with depth and correlated well. Hydraulic pumping tests were conducted to estimate mean values for transmissivity and effective hydraulic conductivity, Tracer lest and geophysical logging results indicated that ground water flow was predominant in the upper approximate 10 feet of the aquifer investigated. These results were used to delineate a more representative interval thickness for estimating effective hydraulic conductivity. Hydraulic conductivity, calculated using this representative interval, was estimated lo be 73 ft/d, approximately three limes higher than that calculated using the full length of the screened test interval. 相似文献
11.
David L. Poulsen Peter G. Cook Craig T. Simmons James L. McCallum Shawan Dogramaci 《Ground water》2019,57(2):269-278
Hydraulic head differences across the screened or open interval of a well significantly influence the sampled water mixture. Sample bias can occur due to an insufficient pumping rate and/or due to native groundwater displacement by intraborehole flow (IBF). Proper understanding of the sampled water mixture is crucial for accurate interpretation of environmental tracers and groundwater chemistry data, and hence groundwater characterization. This paper uses numerical modeling to quantify sample bias caused by IBF in an un-pumped high-yield well, and the influence of pumping rate and heterogeneity on the volume of pumpage required to purge an IBF plume. The results show that (1) the pumping rate must be at least an order of magnitude greater than the IBF rate to achieve permeability-weighted yield, (2) purge volume was 2.2 to 20.6 times larger than the IBF plume volume, with the ratio depending on plume location relative to hydraulic conductivity and head distributions, and (3) after an example 1000-day un-pumped period, purging required removal of at least three orders of magnitude more water than the common practice of three to five well volumes. These results highlight the importance of knowing the borehole flow regime to identify IBF inflow and outflow zones, estimate IBF rates, and to develop a strategic sampling approach. 相似文献
12.
《Ground Water Monitoring & Remediation》2008,28(2):75-80
In a recent field study, the performance of four production wells was evaluated. The intake of a vertical turbine test pump was set below the top of the screened interval of the wells due to anticipated drawdown. Water level sounding tubes were welded to the well casing at various depths in each well. Drawdown data collected at various depths were used to evaluate the vertical head distribution in the wells under various pumping stresses. A direct relationship was observed between the head loss and the location of the pump intake in the production wells. A vertical head profile developed, suggesting that the location of the pump intake controlled the location of water production from the aquifer. The head loss in the wells observed during pumping was directly proportional to well discharge and annulus size between the well casing and the vertical turbine pump shaft. The pressure differences that developed in the wells created increased drawdown in water level sounding tubes installed deep in the wells compared to the total drawdown observed in the production wells. Certain implications should be considered based on the evaluation of the data obtained from this study. Because water management decisions are made using well test data, the quality of the data is crucial. In instances where well performance is evaluated using water level data collected from water level sounding tubes that are located close to a pump intake (in this case deep in the well), it should be recognized that well performance could be underestimated. 相似文献
13.
by Tom Clemo Warren Barrash Edward C. Reboulet Timothy C. Johnson Carsten Leven 《Ground water》2009,47(4):515-525
This paper describes a combined field, laboratory, and numerical study of electromagnetic borehole flowmeter measurements acquired without the use of a packer or skirt to block bypass flow around the flowmeter. The most significant finding is that inflow through the wellbore screen changes the ratio of flow through the flowmeter to wellbore flow. Experiments reveal up to a factor of two differences in this ratio for conditions with and without inflow through the wellbore screen. Standard practice is to assume the ratio is constant. A numerical model has been developed to simulate the effect of inflow on the flowmeter. The model is formulated using momentum conservation within the borehole and around the flowmeter. The model is embedded in the MODFLOW-2000 ground water flow code. 相似文献
14.
Kendrick C. Taylor John W. Hess Aldo Mazzela 《Ground Water Monitoring & Remediation》1989,9(1):100-104
The Geonics EM-39 borehole induction tool was field tested to evaluate its performance under controlled conditions. The effects of temperature changes and borehole fluids were found to be negligible under most conditions. The instrument can be calibrated in large bodies of water of known electrical conductivity. When properly calibrated, the ± 5 percent accuracy claimed by the manufacturer is obtainable. A geologic unit must be at least 4m thick for the electrical conductivity of the unit to be accurately measured. Geologic units thinner than 4m thick can be detected if the conductivity contrast to adjacent units is sufficiently large. 相似文献
15.
Steven C. Young 《Ground water》1995,33(2):311-318
This paper reviews different borehole flowmeter analysis methods and evaluates their applicability to a test site composed of fluvial deposits. Results from tracer and aquifer tests indicate that the aquifer is highly heterogeneous and that low-K skin effects exist at the wells. Borehole flowmeter tests were performed at 37 wells. An appropriate method for calculating borehole flowmeter K values was developed based on results from multiwell pumping tests, single-well pumping tests, and slug tests. The flowmeter data produced 881 K values. The trends and the magnitude of the K values are consistent with results from geologic investigations, recirculating tracer tests, and large-scale multiwell pumping tests. The field tests illustrate that high-K deposits can significantly affect ground-water flows in some heterogeneous fluvial aquifers. 相似文献
16.
Daniel Kurtzman Lior Netzer Noam Weisbrod Ellen R. Graber Daniel Ronen 《Ground water》2011,49(2):275-279
Electrical conductivity (EC) logs were obtained by both open‐borehole logging and passive multilevel sampling (MLS) in an observation borehole penetrating the Coastal Aquifer in Tel Aviv, Israel. Homogeneous vertical velocities for a 70‐m thick subaquifer were approximated from each profile using a steady‐state advection‐diffusion model. The open‐borehole log led to an overestimation of the steady‐state upward advective flux of deep brines (vertical velocity of 0.95 cm/yr as compared to 0.07 cm/yr for the MLS profile). The combination of depth‐dependent data and the suggested simple modeling approach comprises a method for assessing the vertical location of salinity sources and the nature of salt transport from them (i.e., advective vs. diffusive). However, in this case, the easily obtained open‐borehole logs should not be used for collecting depth‐dependent data. 相似文献
17.
Stephen M. Sellwood David J. Hart Jean M. Bahr 《Ground Water Monitoring & Remediation》2015,35(4):85-94
Recent research has demonstrated the use of in‐well heat tracer tests monitored by a fiber optic distributed temperature sensing (DTS) system to characterize borehole flow conditions in open bedrock boreholes. However, the accuracy of borehole flow rates determined from in‐well heat tracer tests has not been evaluated. The purpose of the research presented here is to determine whether borehole flow rates obtained using DTS‐monitored in‐well heat tracer tests are reasonable, and to evaluate the range of flow rates measureable with this method. To accomplish this, borehole flow rates measured using in‐well heat tracer tests are compared to borehole flow rates measured in the same boreholes using an impeller or heat pulse flowmeter. A comparison of flow rates measured using in‐well heat tracer tests to flow rates measured with an impeller flowmeter under the same conditions showed good agreement. A comparison of in‐well heat tracer test flow rate measurements to previously‐collected heat pulse flowmeter measurements indicates that the heat tracer test results produced borehole flow rates and flow profiles similar to those measured with the heat pulse flowmeter. The results of this study indicate that borehole flow rates determined from DTS‐monitored in‐well heat tracer tests are reasonable estimates of actual borehole flow rates. In addition, the range of borehole flow rates measurable by in‐well heat tracer tests spans from less than 10?1 m/min to approximately 101 m/min, overlapping the ranges typically measurable with an impeller flowmeter or a heat pulse flowmeter, making in‐well heat tracer testing a versatile borehole flow logging tool. 相似文献
18.
A common assumption of ground water models formulated using a block-centered finite-difference method is that a well is located at the center of a cell regardless of its actual location. Due to this assumption, errors are introduced in the spatial distribution of simulated heads. This paper presents an alternative approach for assigning the pumping rates of wells that are located off cell centers. This approach consists of assigning the pumping rate not only to the cell in which the well is located but also to adjacent cells, taking into account the length of the well screen, the hydraulic conductivity, and the distance from the well to the center of its cell. The advantage of this alternative approach over the conventional one is illustrated with a test problem of a synthetic aquifer. Statistical measures of error indicate a much better model fit when pumping rates of wells are distributed over several cells. 相似文献
19.
研究各种地层和井眼环境因素对碳氧比C/O测井长、短源距探测器的影响规律，可以为C/O测井仪器的刻度方法提供指导，为解释模型的建立和数据处理提供依据.本文用Monte Carlo方法，计算了C/O值随井眼直径、水泥环厚度、套管直径、孔隙度、含油饱和度、地层岩性和油密度的变化规律.从中看出，当井内流体为油时，井径或套管直径增大，C/O值增大，井眼影响增大；当井内流体为水时，井径或套管直径的增大，C/O值减小；水泥环厚度增加时C/O值减小；当井眼条件不变时，地层孔隙度越大，含油饱和度越大，C/O值越大，对测井越有利；反之，地层孔隙度越小，含油饱和度越小，C/O值越小，对测井不利；地层岩性对C/O值的影响显著，相同条件下，碳酸盐岩比砂岩的C/O值高；油密度越大，C/O值越大.文中还提出了一种消除这些因素影响的数据处理方法 相似文献
20.
Determination of Porosity and Permeability out of Dispersion Analyses of Borehole Wall Displacements
Waves carried in the borehole can be measured by the use of controlled sources inside the borehole and receivers located in
the same borehole as well. This article gives the theoretical background and develops a new method to determine rock-physical
parameters out of such controlled measurements of waves carried inside the borehole. Theoretical dispersion curves of the
group velocities are matched to dispersion analyses of registrations obtained in the borehole. This inversion process intends
to determine the in situ porosity and permeability of the rock. 相似文献