Additional Boreholes Research Articles

Optimal geotechnical site investigations for slope design

Site investigation in combination with field and laboratory testing, plays a vital role in characterizing the soil profile for geotechnical design in order to reduce uncertainty. In spite of this, site investigations are often limited in scope due to high costs. In this paper, conditional random fields are used to examine the influence of soil strength mean, standard deviation and spatial correlation length on the risk of slope design failure for different levels of site investigation scope. An undrained slope example is used to illustrate how the proposed approach can be used to assess the risk reduction that can be obtained as the scope of a site investigation is increased. By combining the cost of site investigation with the cost of slope failure, the results indicate that there exists an optimal site investigation scope, beyond which the cost of additional boreholes does not justify the cost savings due to reduced slope failure risk.

Probabilistic analysis and design of stabilizing piles in slope considering stratigraphic uncertainty

The uncertainty involved in the interpreted geological model may be categorized as the stratigraphic uncertainty and the properties uncertainty. Note that although the influence of the properties uncertainty on the behavior or performance of the geotechnical system and the geotechnical design has been extensively reported in the literature, the studies that address the stratigraphic uncertainty are limited. This paper presents a study regarding the influence of the stratigraphic uncertainty on the behavior of the geotechnical system and the geotechnical design. In which, the uncertainty in the stratigraphic configuration is characterized using the stochastic Markov random field-based approach with a large number of potential stratigraphic realizations. With these stratigraphic realizations as inputs, the influence of the stratigraphic uncertainty on the behavior of the geotechnical system is evaluated in a probabilistic manner; then, the design of the geotechnical system is formulated as a bi-objective optimization-based problem that considers the design safety and the cost simultaneously. To demonstrate the effectiveness of the proposed probabilistic analysis and design approach, the problem of designing stabilizing piles in a slope consisting of multiple strata is studied. The parametric study is further conducted to analyze how the probabilistic analysis results are influenced by the pile parameters and how the probabilistic design results are influenced by the additional boreholes.

3D Design of Optimum Complementary Boreholes by Integrated Analysis of Various Exploratory Data Using a Sequential-MADM Approach

Additional and complementary mineral exploration boreholes are often designed to obtain valuable information about mineralized intervals with the least cost. In this research, a new multi-criteria approach is proposed to design the optimum additional directional boreholes in a 3D environment in the second stage of drilling. The proposed algorithm consists of six steps. In the first step, based on the ore deposit type, exploration stage and available exploration data, the main criteria for the selection of the complementary boreholes are identified. In the second step, 3D geological models associated with the identified criteria are prepared. In the third step, a set of 3D candidate complementary boreholes is designed. In the fourth step, scores along the candidate borehole, relevant to various criteria, are estimated. In the fifth step, the candidate boreholes are ranked using a multi-criteria decision-making algorithm and an optimum borehole is selected for further drilling. Finally, information of new borehole is added to the earlier available data and the above steps are repeated to select additional borehole until a stopping condition for drilling is fulfilled. The proposed algorithm is applied at the Dalli Cu–Au porphyry deposit to design optimum boreholes for further drilling. The considered criteria for designing the additional boreholes are based on magnetic susceptibility, logged hydrothermal alteration, mineralized intervals, length of barren rocks, depth of mineralized intervals, Cu and Au grades along the earlier boreholes and trenches, kriging variance and drilling cost. By using the proposed method, four additional boreholes are designed. These boreholes are located in zones of highest uncertainties and highest grades. By drilling these four boreholes, the accuracy of the grade model is improved by 15%. The proposed approach employs all earlier exploration data to improve designing new boreholes in various deposit types and different stages of drilling.

Quantifying influence of drilling additional boreholes on quality of geological model

Geotechnical stability analysis in open-pit mines requires access to a representative geotechnical model. The confidence level in the collected geotechnical data influences slope design. This paper investigates the influence of the number of boreholes, drilled to collect geological information, on the quality of one component of the geotechnical model, the geological model. The number of boreholes influences the number of rock core samples collected for the identification of rock type, and the definition of geotechnical domains and their boundaries within the rock mass. A challenge in the definition of the geotechnical domains is the determination of the drill hole density that minimizes the variation in the interpreted geological model from the actual rock mass. To quantify the influence of the drill hole density, boreholes are simulated in the most recently updated geological model for three mine sites. The simulated drill hole density is increased progressively until the variation of the interpreted section, compared with the original section, is minimized. A classification strategy was developed to determine the complexity level for each geotechnical domain. Furthermore, a series of empirical quantitative guidelines are presented prescribing the minimum drill hole density per domain complexity, while limiting variations from the actual rock mass.

Characterisation of seismic site effects influenced by near-surface structures using 3D waveform modelling

Seismic waves propagating from source to surface can be significantly affected by vertical and lateral heterogeneities of the near-surface geology. These modified waves can lead to local amplification or attenuation effects of the wave amplitude at the surface. In the assessment of seismic events and the evaluation of possible impacts on infrastructures, the analysis of such site effects is an important issue. In this study, the amplification behaviour of typical near-surface structures in Northern Germany is investigated depending on various parameters to assemble a catalogue of typical structures in the area, which can be used to quickly assess the impact of induced seismic events at the surface. The effect of incoming seismic waves on simple model structures as layer, channel and lens geometries is analysed using 3D waveform simulations with dominant signal frequencies between 1 and 10 Hz based on the spectral element method. The dimensions of the modelled structures range from tens of metres to a few hundred metres. The parameter study shows the dependency of the resulting amplitude at the surface on the impedance contrast, geometrical features and the dominant signal frequency, which are quantified as amplification (attenuation) factors. Simple layer structures reveal low amplification values ranging from 1 to 3.5 and smooth amplification curves, which become more complex for channel and lens type structures while the maximum amplification increases by a factor of two. Focusing and interference effects could be observed depending on the structure type itself as well on the edge shape of the structure. Furthermore, the results of the simple model simulations are used in combination with additional borehole, geological and geophysical data to generate a first large-scale model of the area of the natural gas fields in Northern Germany. Waveform simulations of the large-scale model illustrate the influence of near-surface structures on wave propagation and allow to calculate the amplification behaviour at the surface. These (regional) model simulations can be essential for the reliable assessment of site effects and minimising uncertainties in the interpolation of the ground velocity distribution.

Estimation of hydraulic transmissivity from MRS by varying the porosity exponent in detrital aquifers of the Iberian Peninsula

ABSTRACTTo this date, estimation of hydraulic transmissivity with magnetic resonance sounding (MRS) requires transmissivity values from pumping tests in nearby wells in order to determine a calibration constant from the relationship between both types of data. The use of this technique is limited due to the fact that reported values of this calibration constant are highly variable, even within the same type of aquifer. In order to minimize this shortcoming, a new methodology, which has been developed and presented here, is used to estimate the transmissivity of detrital aquifers with heterogeneous behaviour based only on the results obtained by MRS. The exponents applied to decay time and free porosity used in the expression to compute MRS transmissivity have conventionally been fixed values. In contrast, the work presented here aims to improve the applicability of this technique using a variable exponent for free porosity in each type of aquifer, obtained only from MRS results. In order to achieve this goal, previously published MRS data from four detrital aquifers in the Iberian Peninsula have been used and a relationship between the porosity exponent and a function of decay times and free porosities has been developed. This approach eliminates the need to drill and perform pumping tests in additional boreholes, which has cost and time implications, once the correct expression is determined for a given type of aquifer. The range of values thus obtained for the porosity exponent is similar to that reported in the literature. The deviation of the results obtained with this methodology regarding the results of pumping test is similar to the deviation with conventional process. This suggests that the proposed methodology is appropriate for the aquifers considered, and the approach may be expanded to study other types of aquifers. The drawbacks of the proposal related to the conventional equivalence are explored.

A solar assisted seasonal borehole thermal energy system for a non-residential building in the Mediterranean area

Solar heating and cooling systems are reliable and feasible solutions among renewable energy technologies. Indeed, solar thermal devices help reduce primary energy consumption and can reduce electricity demand, thus representing one of the best options for satisfying heating and/or cooling energy supply. The Borehole Thermal Energy Storage (BTES) represents one of the best promising option among the various storage technologies, because the size of the storage can be easily extended by drilling additional boreholes and simply connecting the pipes to the existing boreholes; the overall energy efficiency of this system is about 40–60%. In this paper, the authors present an application of this technology for the heating system of a school building located in the Southern part of Italy. Two different energy schemes are presented: a school equipped with a conventional gas boiler system with radiators and the same school building with a low temperature heat pump system with fan-coils. All simulations were performed in dynamic state by using TRNSYS software. The results of the analysis assessing the energy and economic performances of the two systems highlighting the advantages of the BTES application in the context of Italian market.

The formation and broken of cuttings bed during reaming process in horizontal directional drilling

Horizontal Directional Drilling (HDD) is an environment-friendly and high efficient method for underground utilities and pipelines crossing. The formation of cuttings bed, due to low Cuttings Transport Performance (CTP) in large-size HDD, has resulted in the overwear of reamer and been required additional borehole cleanups which will result in high construction risk and extending the work period. In order to investigate the formation and broken mechanism of cuttings bed, two tests were designed to determine the potential effect of mud rheological properties, flow rate, borehole inclination and rotation of drill rod on the cuttings bed state. The drill rod laid down at the invert of the borehole, broke the stability state of cuttings bed and take some cuttings away from the cuttings bed, which causes an incremental trend of CTP, even for the cuttings bed consisting of 8–12 mm diameter cuttings. The observations and results of the tests indicated that drill rod rotation had a positive impact on the instability of cuttings bed, whereas, YP of mud, average velocity of mud and borehole inclined shown a limited effect on it for the large-scale HDD reaming. Further study is needed to determine the details about drill rod behavior and extend the tests results by the finite element method.

Analysis of Cross-Borehole Pulse Radar Signatures on a Terminated Tunnel With Various Penetration Lengths

A cross-borehole pulse radar system was operated to detect an intrusive man-made tunnel terminated just 1.2 m away from the line of sight between a newly drilled borehole pair at a tunnel test site. Unlike conventional radar signatures on a fully penetrated air-filled tunnel, the relatively fast arrival in the measured time-of-arrival (TOA) profile was highly suppressed at the depth of the terminated tunnel. To analyze the TOA contraction at a terminated tunnel without drilling additional borehole pairs, a finite-difference time-domain (FDTD) simulator is implemented using the accurately measured location information on the terminated tunnel and borehole pair. The relation curves between the time advance in the TOA profile and the penetration length of the terminated tunnel are plotted in the high and low limits of electrical properties of background rock. To verify the accuracy of our FDTD simulated results, the wideband complex permittivity profiles of the core rock samples’ boring at the tunnel test site are measured using an open-ended coaxial probe method. The calculated time advances agree well with the measured values in both cases of fully penetrated and closely terminated borehole pairs in the test site. The presented time advance curves for various penetration lengths will be a valuable guideline on detection of a terminated tunnel in site.

A method for slope stability analysis considering subsurface stratigraphic uncertainty

The accuracy of stability evaluation of a natural slope consisting of multiple soil and rock layers, regardless the adopted analysis methods, can be highly dependent upon a precise description of the subsurface soil/rock stratigraphy. However, in practice, due to the limitation of site investigation techniques and project budget, stratigraphy of the slope cannot be observed completely and directly; therefore, there remains a considerable degree of uncertainty in the interpreted subsurface soil/rock stratification. Therefore, estimating and minimizing the uncertainty of the computed factor of safety (FS) due to the uncertain site stratigraphy is an important issue in gaining confidence on the stability evaluation outcome. Presented in this paper is a practical analysis approach for evaluating the stability of slopes considering uncertain stratigraphic profiles by incorporating a recently developed stochastic stratigraphic modeling technique into a conventional finite element simulation approach. The stochastic modeling techniques employed for simulating the stratigraphic uncertainty will be briefly described. The main efforts are focused on elucidating the additional benefits from the proposed analysis approach, including a more reasonable probabilistic estimation of FS with consideration of stratigraphic uncertainty, as well as an effective approach for finding the optimum location of additional borehole logs to reduce the uncertainty of FS due to uncertain subsurface stratigraphy.

Elastic Parameters from Compressional and Shear Wave Tomographic Survey: A Case Study from Kuala Lumpur, Malaysia

An integrated P- and S-wave cross-borehole tomographic survey was performed in the city center of Kuala Lumpur, Malaysia, with the aim of exploring a karstic limestone area near an area that previously encountered cavities. Horizontally polarized shear waves were generated with two opposing, perpendicular strike directions and recorded with a multi-level, three-component receiver array. This allowed a high quality picking of the traveltimes, whereby the wave train reverses at the time of the S-wave arrival. In addition, high quality sparker generated P-waves were recorded. The P- and S-wave traveltimes were used to invert for two co-located tomograms. These tomograms enabled a better interpretation capability than a P- or S-wave tomogram on its own. The tomograms enabled the calculation of the elastic parameters, i.e., P- to S-wave velocity (Vp/Vs) ratio, Poisson's ratio, bulk modulus, Young's modulus and the shear modulus, on a 2D surface between the boreholes. This further aided the interpretation, as areas with limited traveltime accuracy and thus, an increase in tomographic error, could be easily identified, and the extent of a large cavity could be estimated. The interpretation of the tomograms was constrained by two additional boreholes, which provided more confidence on the delineation and location of cavities at depths. The survey shows the benefit of co-locating P- and S-wave tomography surveys.

Distance function modeling in optimally locating additional boreholes

The optimal locating of additional boreholes is complicated and very time consuming. Some methods such as metaheuristic algorithms, calculation parallelism, and reducing the time of objective function calculation could be used to increase the calculation speed; among these methods, the latter is preferred due to its extensive influence on the optimization of time. The main reasons that make the objective function calculation cumbersome are mentioned hereafter, and according to their priority: (1) excessive quantity of blocks in the geological block model, and (2) inverting the matrix of average semivariogram between samples is a time consuming operation. The present study aims to decrease the calculation time by reducing the number of blocks without considering their size increment that affects accuracy. To achieve this purpose, the objective function is calculated according to the block model of uncertainty zone, which is defined by using the recently introduced distance function to investigate uncertainty in mineralized domain boundaries. In order to evaluate the performance of the present approach on reducing the calculation time as well as the precision in locating additional boreholes, the results from particle swarm optimization as a metaheuristic algorithm are compared by considering two different scenarios of combined variance reduction on the basis of a three-dimensional geological block model and an uncertainty block model. The comparative results show that using the uncertainty block model reduces the calculation time by one-third, and the proposed locations of the boreholes are more consistent to the study’s aim, which is to reduce the boundary’s uncertainty.

A hybrid fuzzy zoning approach for 3-dimensional exploration geotechnical modeling: a case study at Semilan dam, southern Iran

This paper proposes a hybrid fuzzy zoning approach to compute the spatial variation and design the layout of additional samples during geotechnical investigation of an engineering structure. The geotechnical and geological data of Semilan dam site in southern Iran are utilized to evaluate this methodology. The optimal zoning of the site is found using the Fuzzy c-means (FCM) and comparison of results of various fuzzy clustering validity indices. The borehole samples are assigned to the selected zones according to their fuzzy membership degrees. In each zone, the geostatistical procedures are performed to model the 3-dimensional spatial variability and the related kriging variances. The estimated outputs of four zones are merged to generate the unit and reliable model. After fuzzifying the variables, the uncertainty index is defined as the function of rock quality designation (RQD), Lugeon, lithology index, index of dam structures, and estimation error. To model uncertainty in this site, the Mamdani fuzzy inference system (FIS) is used to establish the rule base relationship between the input and output variables. These outputs of uncertainty can be implemented as a guideline to design the layout of additional exploratory boreholes. In the studied area, five additional boreholes are suggested between the primary network.

Enhancing Magnetic Interpretation Towards Meteorite Impact Crater at Bukit Bunuh, Perak, Malaysia

Bukit Bunuh is the most popular area of suspected meteorite impact crater. In the history of meteorite impact hitting the earth, Bukit Bunuh has complex crater of a rebound zone of positive magnetic anomaly value. This study area was located at Lenggong, Perak of peninsular Malaysia. The crater rim extended 5 km outwards with a clear subdued zone and immediately surround by a positive magnetic residual crater rim zone. A recent study was done to enhance the magnetic interpretation towards meteorite impact crater on this study area. The result obtained is being correlated with boreholes data to determine the range of local magnetic value. For the magnetic survey, the equipment used is Geometric G-856 Proton Precision magnetometers with the aids of other tools such as compass and GPS. In advance, the using of proton precision magnetometer causes it able in measures the magnetic fields separately within interval of second. Also, 18 boreholes are accumulated at study area to enhance the interpretation. The additional boreholes data had successfully described the structure of the impact crater at Bukit Bunuh in detailed where it is an eroded impact crater. Correlations with borehole records enlighten the results acquired from magnetic methods to be more reliable. A better insight of magnetic interpretation of Bukit Bunuh impact crater was done with the aid of geotechnical methods.

Urinary schistosomiasis in communities around Kiri Lake, Shelleng Local Government Area, Adamawa State, Nigeria

The objectives of the study were to determine the prevalence of urinary schistosomiasis in the different communities, the intensity of infection, prevalence among gender and age groups and to relate infection with parent’s occupation. A study on the prevalence of urinary schistosomiasis was conducted in four villages around Kiri Lake in Shelleng Local Government Area, Adamawa State, Nigeria. Two hundred and thirty two urine samples were collected from four primary school children randomly selected from within the four study communities. Overall, prevalence of urinary schistosomiasis was 48% (111/232), with males recording 49% (69/142) and females 47% (42/90). The total mean egg count (MEC) was 8.3. There was no significant difference in prevalence between males and females (P˃0.05). Prevalence was higher among age groups, with the 13-15 year old age group having the highest 62.96% (17/27) and the 4-6 year old age group had the least 37% (19/52). There was no statiscally significant difference in prevalence among the different age groups (P>0.05). Infection was also high among children of fishermen 59.09% (13/22), followed by farmers’ children 56.25% (45/80) and the least prevalence was among children of teachers 20% (3/15). Old Banjiram had the highest infection of 91% (21/23), while Kwadadai had the least 36.8% (21/57) (P<0.05). Old Banjiram and children in the 10-12 years age group had the highest mean egg count of 10.6 and 9.4 respectively. The study reveals a high prevalence of urinary schistosomiasis. And therefore portable water source should be made functional in all communities surrounding the lake. While rehabilitation and repair of the existing water borehole system in the community should be effected as well as drilling new additional boreholes to serve their water needs. Commun JASEMity participatory health education on this neglected tropical disease in the area is needed on knowledge of the disease, the intermediate host and transmission pattern. Since school children harbour infection and are a source of infection of schistosomiasis in endemic communities, planning and provision for their treatment should be considered in control programmes. Keywords: Schistosoma haematobium , Prevalence, Kiri lake, Socio-economic, School children, Nigeria

High‐resolution reflection seismic imaging for the planning of a double‐train‐track tunnel in the city of Varberg, southwest Sweden

ABSTRACTA newly developed broadband digital‐based seismic landstreamer system was employed for the planning of a double‐train‐track tunnel in the city of Varberg, southwest Sweden. Twenty‐five seismic profiles, totalling more than 7.5 km of data, were acquired using a 2‐ to 4‐m receiver and source spacing. At places where it was not possible to move the streamer such as road crossings, wireless recorders connected to 28‐Hz geophones were used. In addition to the earlier refraction data analysis and first‐break traveltime tomographic modelling, reflection processing of the data was considered in this study, given the realisation of reflections in raw shot gathers and their good quality. Bedrock is strongly reflective in most cases but is not evident in the sections when it gets near the surface. Bedrock undulation is noticeable in most reflection sections, and at one occasion, strong diffraction is observed in the bedrock or near to it. The diffraction is originated, not known during the survey, from a 400‐m3 cylindrical (of about 3‐m‐height and 13‐m‐diameter) concrete‐made fire‐protection water tank situated in the bedrock and used in emergency situations. Reflection seismic data greatly complement the tomographic models and support deep bedrock where the excavation of the tunnel is planned in downtown Varberg. This interpretation implies different reinforcements and tunnel construction methods (e.g., roofed concrete) at this section of the tunnel. In addition, weakness zones associated with fracture systems are inferred from the reflection characteristics and in conjunction with the velocity models requiring verification by additional boreholes.

2D probabilistic prediction of sparsely measured earth properties constrained by geophysical imaging fully accounting for tomographic reconstruction ambiguity

Many hydrological, environmental, or engineering exploration tasks require predicting spatially continuous scenarios of sparsely measured borehole logging data. We present a methodology to probabilistically predict such scenarios constrained by ill-posed geophysical tomography. Our approach allows for transducing tomographic reconstruction ambiguity into the probabilistic prediction of spatially continuous target parameter scenarios. It is even applicable to data sets where petrophysical relations in the survey area are non-unique, i.e., different facies related petrophysical relations may be present. We employ static two-layer artificial neural networks (ANNs) for prediction and additionally evaluate, whether the training performance of the ANNs can be used to rank geophysical tomograms, which are mathematically equal reconstructions of physical parameter distributions in the ground. We illustrate our methodology using a realistic synthetic database for maximal control about the prediction performance and ranking potential of the approach. For doing so, we try to link geophysical radar and seismic tomography as input parameters to porosity of the ground as target parameter of ANN. However, the approach is flexible and can cope with any combination of geophysical tomograms and hydrologic, environmental or engineering target parameters. Ranking of equivalent geophysical tomograms based on additional borehole logging data is found to be generally possible, but risks remain that the ranking based on the ANN training performance does not fully coincide with the closeness of geophysical tomograms to ground truth. Since geophysical field data sets do usually not offer control options similar to those used in our synthetic database, we do not recommend the utilization of recurrent ANNs to learn weights for the individual geophysical tomograms used in the prediction procedure.

A scaled down laboratory experiment of cross-borehole pulse radar signatures for detection of a terminated tunnel

In the cross-borehole pulse radar signatures measured near the front end of a terminated tunnel, the time-of-arrival (TOA) with fully penetrated tunnel is significantly shortened due to the relatively fast pulse propagation in an empty tunnel compared with the TOA obtained without a tunnel. To analyze the TOA variation with the protrusion length of the terminated tunnel from the line-of-sight between two antennas or boreholes, additional borehole pairs are required around the terminated tunnel in spite of their high construction costs. As an alternative, a laboratory scaled down experiment, which has a high ability to simulate different underground configurations, is designed for investigation into the TOA effects of tunnel termination. A round ceramic rod with a careful selection of its dielectric constant is immersed in pure water in a water tank and used to simulate the tunnel in the experiment. Coaxial fed dipole antennas with balanced wire and ferrite cores are used not only to suppress borehole-guided waves but also to generate a symmetric radiation pattern. The accuracy of the laboratory scaled down experiment is verified by the symmetricity of the measured diffraction pattern of the fully penetrated ceramic rod. Then, the TOA variation is measured for the protrusion length of the ceramic rod relative to the line-of-sight between two antennas from +80 mm to −80 mm with an equal step of 5 mm. Based on the scaled down experimental measurements of the TOA, it is found that a tunnel 1.2 m away from the measuring cross-borehole section closely approaches the scaled up variation curve under the same conditions of the protrusion length.

Comparison of particle swarm optimization and simulated annealing for locating additional boreholes considering combined variance minimization

One of the most important stages in complementary exploration is optimal designing the additional drilling pattern or defining the optimum number and location of additional boreholes. Quite a lot research has been carried out in this regard in which for most of the proposed algorithms, kriging variance minimization as a criterion for uncertainty assessment is defined as objective function and the problem could be solved through optimization methods. Although kriging variance implementation is known to have many advantages in objective function definition, it is not sensitive to local variability. As a result, the only factors evaluated for locating the additional boreholes are initial data configuration and variogram model parameters and the effects of local variability are omitted. In this paper, with the goal of considering the local variability in boundaries uncertainty assessment, the application of combined variance is investigated to define the objective function. Thus in order to verify the applicability of the proposed objective function, it is used to locate the additional boreholes in Esfordi phosphate mine through the implementation of metaheuristic optimization methods such as simulated annealing and particle swarm optimization. Comparison of results from the proposed objective function and conventional methods indicates that the new changes imposed on the objective function has caused the algorithm output to be sensitive to the variations of grade, domain's boundaries and the thickness of mineralization domain. The comparison between the results of different optimization algorithms proved that for the presented case the application of particle swarm optimization is more appropriate than simulated annealing.

Optimal experimental design for reservoir property estimates in geothermal exploration

During geothermal reservoir development, drilling deep boreholes turns out to be extremely expensive and risky. Thus, it is of great importance to work out the details of suitable borehole locations in advance. Here, given a set of existing boreholes, we demonstrate how a sophisticated numerical technique called optimal experimental design helps to find a location of an additional exploratory borehole that reduces risk and, ultimately, saves cost. More precisely, the approach minimizes the uncertainty when deducing the effective permeability of a buried reservoir layer from a temperature profile measured in this exploratory borehole. In this paper, we (1) outline the mathematical formulation in terms of an optimization problem, (2) describe the numerical implementation involving various software components, and (3) apply the method to a 3D numerical simulation model representing a real geothermal reservoir in northern Italy. Our results show that optimal experimental design is conceptually and computationally feasible for industrial-scale applications. For the particular reservoir and the estimation of permeability from temperature, the optimal location of the additional borehole coincides with regions of high flow rates and large deviations from the mean temperature of the reservoir layer in question. Finally, the presentation shows that, methodologically, the optimization method can be generalized from estimating permeability to finding any other reservoir properties.