Multi-well Systems Research Articles

A New Algorithm Model Based on Extended Kalman Filter for Predicting Inter-Well Connectivity

Given that more and more oil reservoirs are reaching the high water cut stage during water flooding, the construction of an advanced algorithmic model for identifying inter-well connectivity is crucial to improve oil recovery and extend the oilfield service life cycle. This study proposes a state variable-based dynamic capacitance (SV-DC) model that integrates artificial intelligence techniques with dynamic data and geological features to more accurately identify inter-well connectivity and its evolution. A comprehensive sensitivity analysis was performed on single-well pairs and multi-well groups regarding the permeability amplitude, the width of the high permeable channel, change, and lasting period of injection pressure. In addition, the production performance of multi-well groups, especially the development of ineffective circulation channels and their effects on reservoir development, are studied in-depth. The results show that higher permeability, wider permeable channels, and longer injection pressure maintenance can significantly enhance inter-well connectivity coefficients and reduce time-lag coefficients. Inter-well connectivity in multi-well systems is significantly affected by well-group configuration and inter-well interference effects. Based on the simulation results, the evaluation index of ineffective circulation channels is proposed and applied to dozens of well groups. These identified ineffective circulation channel changing patterns provide an important basis for optimizing oil fields’ injection and production strategies through data-driven insights and contribute to improving oil recovery. The integration of artificial intelligence enhances the ability to analyze complex datasets, allowing for more precise adjustments in field operations. This paper’s research ideas and findings can be confidently extended to other engineering scenarios, such as geothermal development and carbon dioxide storage, where AI-based models can further refine and optimize resource management and operational strategies.

Tunneling splittings using modified WKB method in Cartesian coordinates: The test case of vinyl radical.

Modified WKB theory for calculating tunneling splittings in symmetric multi-well systems in full dimensionality is re-derived using Cartesian coordinates. It is explicitly shown that the theory rests on the wavefunction that is exact for harmonic potentials. The theory was applied to calculate tunneling splittings in vinyl radical and some of its deuterated isotopologues in their vibrational ground states and the low-lying vibrationally excited states and compared to exact variational results. The exact results are reproduced within a factor of 2 in most states. Remarkably, all large enhancements of tunneling splittings relative to the ground state, up to three orders in magnitude in some excited mode combinations, are well reproduced. It is also shown that in the asymmetrically deuterated vinyl radical, the theory correctly predicts the states that are localized in a single well and the delocalized tunneling states. Modified WKB theory on the minimum action path is computationally inexpensive and can also be applied without modification to much larger systems in full dimensionality; the results of this test case serve to give insight into the expected accuracy of the method.

Stochastic Syncing in Sinusoidally Driven Atomic Orbital Memory.

Stochastically fluctuating multiwell systems are a promising route toward physical implementations of energy-based machine learning and neuromorphic hardware. One of the challenges is finding tunable material platforms that exhibit such multiwell behavior and understanding how complex dynamic input signals influence their stochastic response. One such platform is the recently discovered atomic Boltzmann machine, where each stochastic unit is represented by a binary orbital memory state of an individual atom. Here, we investigate the stochastic response of binary orbital memory states to sinusoidal input voltages. Using scanning tunneling microscopy, we investigated orbital memory derived from individual Fe and Co atoms on black phosphorus. We quantify the state residence times as a function of various input parameters such as frequency, amplitude, and offset voltage. The state residence times for both species, when driven by a sinusoidal signal, exhibit synchronization that can be quantitatively modeled by a Poisson process based on the switching rates in the absence of a sinusoidal signal. For individual Fe atoms, we also observe a frequency-dependent response of the state favorability, which can be tuned by the input parameters. In contrast to Fe, there is no significant frequency dependence in the state favorability for individual Co atoms. Based on the Poisson model, the difference in the response of the state favorability can be traced to the difference in the voltage-dependent switching rates of the two different species. This platform provides a tunable way to induce population changes in stochastic systems and provides a foundation toward understanding driven stochastic multiwell systems.

Hydrate reservoir deformation under multi-well strategies based on the dynamic elastic modulus relationship

In order to demonstrate the safety of the multi-well mining method, stratum deformation using multi-well systems is discussed. Firstly, ultrasonic experiments and triaxial tests of hydrate-bearing sediments under different confining pressure and hydrate saturation conditions were carried out. The soil static elastic modulus was compared with the dynamic elastic modulus relationship. Then the dynamic elastic modulus relations were applied to the multi-field coupling model to simulate the hydrate mining process in reservoirs by multi-well strategies. The experimental results show that hydrate saturation impacts the elastic modulus more than the effective confining pressure. In the simulation results, with the increase of the reservoir depth, the soil settlement shows a trend from small to large and then to small. The maximum soil displacement is located at the junction between the hydrate and the overlying layers, regarded as the weak point. In addition, increasing the well branches, expanding the well spacing, and increasing the wellhead radius can increase gas production. However, at the same time, it will also increase the reservoir deformation, thus posing risks to the stability of the formation and extraction wells. On this basis, the efficiency-safety factor was set, and the best mining scheme was determined.

Numerical analysis on hydrate production performance with multi-well systems: Synergistic effect of adjacent wells and implications on field exploitation

Multi-well technology is an alternative method to achieve commercialization development of the gas hydrate, which further requires proper production strategies. However, its stimulation mechanisms remain unclear, especially the synergistic effects of adjacent wells, restricting the production strategy formulation. Thus, we established a 3D model to characterize multi-physics fields, flow characteristics, as well as productivity of hydrate reservoirs on a large scale. It can display the fluid flow in complex geometries, realizing the accurate characterization of the flow field during hydrate production with multi-well systems. Total productivity of optimal multi-well systems can be 1.44 times higher than all single wells independently, Meanwhile, physical fields and flow characteristics alter with the well position as well as well number. After that, an index Ise is proposed to realize the quantitative evaluation of the impact of synergistic effect on productivity. The impact of synergistic effect strengthens continuously versus duration time and well spacing. In addition, the occurring synergistic effect can increase productivity by promoting hydrate dissociation in expanded pressure drop areas. In contrast, the fluid resistance effect decreases the per-well produced gas and water due to inflow reduction induced by inter-well interference. Moreover, an estimation model is established to identify the proper well spacing for lower drilling costs and larger productivity. This work will enable the extended application of multi-well systems with the synergistic effect and further promote the efficient development of the gas hydrate.

CRM-Aquifer-Fractional Flow Model to Characterize Oil Reservoirs with Natural Water Influx

Summary This work presents a new flow model that uses production data to characterize conventional undersaturated oil reservoirs with natural water influx in primary production. The main application is to estimate the original oil in place (OOIP), but the model also calculates the productivity index (PI), water influx, and heterogeneity factor. Aquifers are common to many reservoirs and their diagnosis is relevant because they can serve as an important drive mechanism but can also affect well productivity. Discerning between the reservoir and aquifer volumes is also a major challenge in many oil fields. Reservoir-aquifer systems have been investigated with various dynamic characterization techniques such as the material balance equation (MBE), pressure transient analysis, and production/rate transient analysis. These methods have limitations, for example, requiring shut-in wells and/or very large production histories and high mobility and compressibility ratios to yield distinguishable responses in the diagnostic plots. The new flow model couples the producer-based capacitance resistance model (CRMP) with the Fetkovich aquifer model (CRMPA). It enables calculating the total instantaneous production flow rate from a well as a function of three mechanisms—reservoir depletion, changes in bottomhole pressure (BHP), and water influx. In addition, CRMPA is coupled with the Koval fractional flow model (capacitance resistance aquifer-fractional flow model, CRMPAF) to calculate the individual oil and water rates and to enhance the OOIP estimation for wells with two-phase production caused by water breakthrough from the aquifer. The capacitance resistance model (CRM) is a production analysis technique that uses rate and pressure data from typical field surveillance (no dedicated tests) to characterize reservoir properties. It has been widely used to study reservoirs under secondary and tertiary recovery. There are a few applications for primary recovery, and only one reference investigated natural water influx. There are important differences between the previously published and the new CRMPA formulations. The former estimated the individual water influx to each well in a multiwell reservoir associated with an aquifer. The calculations were performed assuming the reservoir pore volume (PV) was known, whereas the present approach simultaneously calculates the PV and the water influx. The former approach also required a priori knowledge of the average pressure, obtained from buildup tests, whereas the new method uses production data, (i.e., it does not require shut-in wells). In the new approach, CRMP (without aquifer) is first used to calculate the capacitance/resistance (CR) parameters of the equivalent (reservoir-aquifer) medium. It provides the correct OOIP for volumetric reservoirs; however, CRMPA is used when the PV significantly differs from volumetrics and water influx is detected. CRMPA calculates the reservoir CR parameters using simple relationships between the equivalent and composite mediums. For wells with two-phase production, the Koval factor is an additional parameter. The CRMPA/F solution is obtained by minimizing the errors between the calculated and measured rates over a time window. The new CRMPA/F approach is compared and validated with several models of single and multiwell synthetic reservoir-aquifer systems with different properties and geometries. It is also used to characterize a field case.

Study on the intrinsic mechanisms underlying enhanced geothermal system (EGS) heat transfer performance differences in multi-wells

The effectiveness of the multi-well arrangement mode in enhanced geothermal systems in large-scale fields has been well established. However, the mechanisms that lead to variations in heat transfer performance between different numbers of well arrangements have remained unclear. In this study, the multi-well pattern was segmented into several double-well units and a mathematical model was constructed to investigate seepage heat transfer in enhanced geothermal systems using numerical simulation techniques. The lifespan and heat transfer characteristics of both multi-well and corresponding double-well units were examined, with supplementary experimental validation. Additionally, a flow reduction coefficient for multi-well systems was proposed to explain the differences in heat transfer performance caused by the pressure superposition of multiple-well seepage fields. It was found that heat extraction from a multi-well enhanced geothermal system is equivalent to the linear superposition of corresponding double-well units. Furthermore, the lifespan of multi-well systems is significantly longer than that of corresponding double-well systems due to the influence of the multi-well flow reduction coefficient. In fact, this difference can exceed threefold in nine-well arrangements, resulting in reduced efficiency of multi-well heat exchange. This work provides a novel perspective on exploring the intrinsic mechanisms that underlie differences in heat transfer performance in enhanced geothermal systems from a flow field perspective. It contributes to a better understanding of optimal well arrangement modes for enhanced geothermal systems and supports the development of large-scale geothermal fields.

Well interference evaluation considering complex fracture networks through pressure and rate transient analysis in unconventional reservoirs

Severe well interference through complex fracture networks (CFNs) can be observed among multi-well pads in low permeability reservoirs. The well interference analysis between multi-fractured horizontal wells (MFHWs) is vitally important for reservoir effective development. Well interference has been historically investigated by pressure transient analysis, while it has shown that rate transient analysis has great potential in well interference diagnosis. However, the impact of complex fracture networks (CFNs) on rate transient behavior of parent well and child well in unconventional reservoirs is still not clear. To further investigate, this paper develops an integrated approach combining pressure and rate transient analysis for well interference diagnosis considering CFNs. To perform multi-well simulation considering CFNs, non-intrusive embedded discrete fracture model approach was applied for coupling fracture with reservoir models. The impact of CFN including natural fractures and frac-hits on pressure and rate transient behavior in multi-well system was investigated. On a log–log plot, interference flow and compound linear flow are two new flow regimes caused by nearby producers. When both NFs and frac-hits are present in the reservoir, frac-hits have a greater impact on well #1 which contains frac-hits, and NFs have greater impact on well #3 which does not have frac-hits. For all well producing circumstances, it might be challenging to see divergence during pseudosteady state flow brought on by frac-hits on the log–log plot. Besides, when NFs occur, reservoir depletion becomes noticeable in comparison to frac-hits in pressure distribution. Application of this integrated approach demonstrates that it works well to characterize the well interference among different multi-fractured horizontal wells in a well pad. Better reservoir evaluation can be acquired based on the new features observed in the novel model, demonstrating the practicability of the proposed approach. The findings of this study can help for better evaluating well interference degree in multi-well systems combing PTA and RTA, which can reduce the uncertainty and improve the accuracy of the well interference analysis based on both field pressure and rate data.

Numerical simulation of gas extraction performance from hydrate reservoirs using double-well systems

Multi-well systems can increase the drainage area and hence enhance the productivity of natural gas hydrate (NGH) production. Fundamentally, the double-well system is the key and basis of understanding the multi-well system and formulating field strategies for gas extraction from hydrate-bearing sediments. However, production performance and multi-well production strategies for recovering NGH by using depressurization have not been treated in detail. Here we develop a three-dimensional model to describe double-well production characteristics from the low-permeability hydrate reservoir and analyze well-deployment strategies. The productivity of this double-well system is 1.5–2.5 higher than that of the single well under the same conditions, which is triggered by enlarging the drainage area. The well spacing alters flow characteristics and corresponding geophysical fields, which is the key variable for the double-well system in gas recovery. Its range can be determined based on the combination of productivity and hydrate dissociation front. Besides, due to the limited enhancement in productivity using the double-well system, the multi-well system assisted with reservoir reconstruction technologies and stimulation methods is of significant practical value in realizing commercial exploitation of NGH.

Design and investigation of a quad-stable piezoelectric vibration energy harvester by using geometric nonlinearity of springs

In this paper, a quad-stable piezoelectric vibration energy harvester induced by the geometric nonlinearity of springs is designed and investigated. The novelty is that by replacing the permanent magnets with a combination of springs, the system can be effectively protected from electromagnetic interference in the working environment. The innovative design of three hinged springs attached to the tip of the cantilever beam makes the stiffness of the structure inherently nonlinear, which can induce the multi-stability of the system. The Euler-Lagrange equations are applied to establish the governing equation of the energy harvester. The static bifurcation analysis reveals the evolution process of multi-stability. The complex dynamic frequency (CDF) method, an efficient approach to solving strongly nonlinear dynamic problems with multi-well systems, is then applied to deduce the system's amplitude-frequency response. Combinations of theoretical and numerical results show that among a wide frequency bandwidth, the system can exhibit such as single-, double- and quadruple-well periodic motions. Finally, experiments are set up to verify the advantage of inter-well motion on harvesting power. Result shows that geometric nonlinearity can effectively make the energy harvester exhibit multi-stability, generate different movement patterns, and obtain high harvesting power.

Production efficiency analysis in hydrate reservoir under multi-well systems

To achieve the goal of carbon emission reduction, the hydrate is widely concerned for its outstanding advantages such as high calorific value and low pollution. As the output of natural gas still cannot meet the requirements of commercial exploitation, multi-well exploitation will become a technological trend in the future. Therefore, the depressurization mining of hydrate reservoirs under multi-well systems was simulated. The influences of the well branch number, well spacing, and wellhead radius on the soil depressurization characteristics were analyzed. Moreover, two new parameters, depressurization and decomposition areas, are defined to analyze the reservoir depressurized effect and production efficiency. The results show that the more the number of wells, the better the depressurization effect and the longer the duration. The decomposition efficiency of multi-well production in the late mining stage is much higher than that of single-well production. The gas production by multi-well cooperative production is much higher than that by single well production with the same number.

Using Agarwal analytical approach with superposition rate and time solutions to analyze multi and single well systems

There are many RTA (Rate Transient Analysis) methods available to analyze wells producing from unconventional formations. The approach of Agarwal (2010) is one of the RTA techniques which have gained an increasing interest due to its simplicity, flexibility, and wide range of applications. In this study, the approach of Agarwal (2010) was adopted to analyze not only single well systems but also multi-well systems by using three different equations. These equations were then integrated with the principle of superposition rate rather than conventional superposition time. By using two field cases, the accuracy of the proposed approaches was validated with current analytical methods and reservoir simulation. The first case represents a multi-well system in which the wells producing with a fixed flowing pressure were put on production at the same time. The operating conditions were then relaxed in the second case by allowing the wells to have different production starting times and varying production profiles.Additionally, this work examined in details the ability of the superposition rate function in converting various production behaviors to their equivalent constant rate solutions. This research clearly shows the advantage of the superposition rate solution over the traditional superposition time function (material balance time) in maintaining the data order in time. Such an advantage makes it easier for the analyst to observe the production changes in well performance in real normal time.Several case studies were used to show how Agarwal (2010) can be utilized to extract different information from boundary-dominated flow period which are useful in the evaluation of reservoir compartmentalization and the effectiveness of infill drilling campaigns. In addition to that, the application of Agarwal (2010) in terms of frac hits evaluation and refracturing operations encountered during the transient flow period was also examined.

Analytical well-test model for hydraulicly fractured wells with multiwell interference in double porosity gas reservoirs

Interference resulting from infill wells in multiwell systems becomes a common issue in interpreting well tests data from hydraulicly fractured wells in tight carbonate gas reservoirs. Current single-well pressure transient approaches may falsely interpret well interferences as the composite reservoir or boundary effects, leading to significant errors in reservoir parameter estimation. Additionally, the most semi-analytical and numerical solutions used for fractured wells are computationally demanding and inconvenient to use. This work presents a novel and simple analytical well-test model for hydraulicly fractured wells with multiwell interference in double porosity gas reservoirs with significantly less computational time and effort than the existing methods. The analytical solution for a hydraulically fractured well with finite conductivity fracture in a multiwell system with well interference is presented based on the superposition principle, the early-time approximate solutions of trilinear flow and the infinite-conductivity fracture model. A systematic verification is conducted to ensure the validity of the presented solution. The solution is valid when the dimensionless fracture conductivity is greater than 1 (FcD>1) with ∼1% error in pressure and derivative. Furthermore, we offer a criterion of identifying well interference using the pressure derivative of the late-time approximation of the proposed analytical solution. Finally, a case study is conducted in the Sichuan Basin, indicating the proposed solution's applicability.

Performance study on the seepage and heat transfer in a bench-scale multi-well infiltration intake system for seawater source heat pump

The Beach Well Infiltration Intake (BWII) system is one of the various methods for pumping seawater for Seawater Source Heat Pump (SWHP) systems that improve the stability, reliability, and energy efficiency of the SWHP systems in cold climate areas. Because of the limitations of the site conditions, it is difficult to perform experimental studies on the BWII system under different experimental conditions, especially for multi-well systems. Therefore, a BWII experimental system that incorporated nine beach wells was established in a laboratory in this paper. The goal was to study the seepage and heat transfer performance of the multi-well infiltration intake system and calculate the influencing range for pumping groundwater on sands in a sandbox. Then, an established seepage and heat transfer model of the BWII system was validated by the experiment. Based on the validated model, the method for designing an experimental sandbox was studied. The research results showed that the effective width increased with an increase in the distance between the pumping well and the long water tank. However, the effective width in the back part of the pumping well decreased with an increase in this distance. The result that the effective length decreased with an increase in this distance was contrary to our subjective expectations. When the distance between the pumping well and the long water tank was 0.5 m, the effective length and effective width were 1.5 ∼ 2.1 m and 0.9 m respectively. The formulas of the effective width and the effective length were derived. The experimental study provided a method to study the seepage and heat transfer performance of the BWII system and was complementary to the theoretical research and the practical engineering field research. The research results provided in this study will contribute to the establishment of a set of seepage heat transfer similarity test methods.

Non-minimizing connecting orbits for multi-well systems

Given a nonnegative, smooth potential \(V: {{\mathbb {R}}}^k \rightarrow {{\mathbb {R}}}\) (\(k \ge 2\)) with multiple zeros, we say that a curve \({\mathfrak {q}}: {{\mathbb {R}}}\rightarrow {{\mathbb {R}}}^k\) is a connecting orbit if it solves the autonomous system of ordinary differential equations $$\begin{aligned} {\mathfrak {q}}''= \nabla _{\mathbf{u}} V({\mathfrak {q}}) , \quad \text{ in }\;\, {{\mathbb {R}}}\end{aligned}$$and tends to a zero of V at \(\pm \infty \). Broadly, our goal is to study the existence of connecting orbits for the problem above using variational methods. Despite the rich previous literature concerning the existence of connecting orbits for other types of second order systems, to our knowledge only connecting orbits which minimize the associated energy functional in a suitable function space were proven to exist for autonomous multi-well potentials. The contribution of this paper is to provide, for a class of such potentials, some existence results regarding non-minimizing connecting orbits. Our results are closely related to the ones in the same spirit obtained by J. Bisgard in his PhD thesis (University of Wisconsin-Madison, 2005), where non-autonomous periodic multi-well potentials (ultimately excluding autonomous potentials) are considered. Our approach is based on several refined versions of the classical Mountain Pass Lemma.

Unusual spin-orbit control in AlInAs/GaInAs triple wells triggered by band crossing and anticrossing

Additional orbital degrees of freedom in multiband quantum systems may offer more intriguing possibilities for spin-orbit (SO) control. Here we explore the Rashba and Dresselhaus SO couplings in realistic AlInAs/GaInAs triple wells subjected to top $({V}_{\mathrm{T}})$ and back $({V}_{\mathrm{B}})$ gate potentials, allowing for flexible triple-occupancy control for electrons. By performing a self-consistent Poisson-Schr\"odinger calculation, we determine all the relevant Rashba (Dresselhaus) SO terms of both intraband ${\ensuremath{\alpha}}_{\ensuremath{\nu}}$ $({\ensuremath{\beta}}_{\ensuremath{\nu}})$ and interband ${\ensuremath{\eta}}_{\ensuremath{\mu}\ensuremath{\nu}}$ $({\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\mu}\ensuremath{\nu}})$ types. For a structurally symmetric triple well, we achieve a crossing of energy levels between the first and second subbands and sequentially an anticrossing between the second and third subbands, accompanied with a double band swapping, simply via adjusting ${V}_{\mathrm{B}}$. As a consequence, when ${V}_{\mathrm{B}}$ varies, an emerging interchange of the first-subband ${\ensuremath{\alpha}}_{1}$ $({\ensuremath{\beta}}_{1})$ and second-subband ${\ensuremath{\alpha}}_{2}$ $({\ensuremath{\beta}}_{2})$ SO terms, and of ${\ensuremath{\alpha}}_{2}$ $({\ensuremath{\beta}}_{2})$ and ${\ensuremath{\alpha}}_{3}$ $({\ensuremath{\beta}}_{3})$ respectively for the second and third subbands, i.e., double SO interchange, occurs, greatly fascinating for selective SO control among distinct subbands in spintronic devices. Further, near the two-band swapping points, across which electron transfer among the three local wells (triple well) takes place, detailed interchanging features of nonlinear SO control are also contrasting. Remarkably, in addition to Rashba terms, we also realize a wide-range control of Dresselhaus couplings, which are usually immune to electrical manipulation. Regarding the interband Rashba and Dresselhaus SO contributions, ${\ensuremath{\eta}}_{\ensuremath{\mu}\ensuremath{\nu}}$ and ${\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\mu}\ensuremath{\nu}}$ exhibit either a resonant behavior or a steplike jump across band-swapping points, depending on the parity and spatial distribution of electron wave functions. By varying the barrier height of the two inner barriers in the triple-well configuration, dependence of relevant SO terms on engineered structures, which are either structurally symmetric or asymmetric, is also discussed. Interestingly, in the latter asymmetric case, we realize a seemingly symmetric configuration by adjusting ${V}_{\mathrm{B}}$, in which ${\ensuremath{\alpha}}_{1}$ and ${\ensuremath{\alpha}}_{2}$ essentially vanish while ${\ensuremath{\alpha}}_{3}$ is nonzero, providing a handle for suppressing electron spin relaxation of chosen subbands. Our results will stimulate more experiments probing unusual SO features in multiband and multiwell quantum systems and act as a guide for more proposals designed for spintronic devices.

Global invariant manifolds delineating transition and escape dynamics in dissipative systems: an application to snap-through buckling

Invariant manifolds play an important role in organizing global dynamical behaviors. For example, it is found that in multi-well conservative systems where the potential energy wells are connected by index-1 saddles, the motion between potential wells is governed by the invariant manifolds of a periodic orbit around the saddle. In two-degree-of-freedom systems, such invariant manifolds appear as cylindrical conduits which are referred to as transition tubes. In this study, we apply the concept of invariant manifolds to study the transition between potential wells in not only conservative systems, but more realistic dissipative systems, by solving respective proper boundary value problems. The example system considered is a two-mode model of the snap-through buckling of a shallow arch. We define the transition region, $$\mathcal {T}_h$$ , as a set of initial conditions of a given initial Hamiltonian energy h with which the trajectories can escape from one potential well to another, which in the example system corresponds to snap-through buckling of a structure. The numerical results reveal that in the conservative system, the boundary of the transition region, $$\partial \mathcal {T}_h$$ , is a cylinder, while in the dissipative system, $$\partial \mathcal {T}_h$$ is an ellipsoid. The algorithms developed in the current research from the perspective of invariant manifold provide a robust theoretical–computational framework to study escape and transition dynamics.

Optimizing Multiwell Aquifer Storage and Recovery Systems for Energy Use and Recovery Efficiency.

As more aquifer storage and recovery (ASR) systems are employed for management of water resources, the skillful operation of multiwell ASR systems has become very important to improve their performance. In this study, we developed MODFLOW and MT3DMS models to simulate a multiwell ASR system in a synthetic aquifer to assess effects of hydrogeological and operational factors on the performance of the multiwell ASR system. We evaluated a simplified (dual well) ASR system in comparison with complex system (three-, four-, five-, and seven-well systems). Recovery and energy efficiencies were calculated using the model simulations. Factors such as higher hydraulic conductivity and longitudinal dispersivity significantly reduced the recovery and energy efficiencies of the system. In contrast, increasing the volume of recharged water increased the recovery efficiency; however, the energy efficiency was reduced. Recovery and energy efficiencies also plummet when there is an increase in the underlying regional gradient and the designed storage duration. Operating the system multiple times can yield higher volume of potable water, but the energy efficiency may not vary significantly after the second operating cycle. Single-well systems and multiwell systems exhibit similar responses to changes in physical factors, although operational factors have a more pronounced effect on the multiwell systems. One of the major findings was that fewer wells in a multiwell ASR system can yield higher volume of potable water and better output with respect to the electrical power being consumed. The results provide design engineers with guidelines for optimizing performance of the multiwell ASR systems.

Interference between geothermal doublets across a fault under subsurface uncertainty; implications for field development and regulation

Direct Use Geothermal Systems (DUGS) are increasing their installed capacity worldwide and denser developments with multiple doublets are becoming more common. Interference between doublets therefore becomes an additional concern to subsurface uncertainties. Faults can be either barriers or conduits to flow and can affect the fluid pathways inside the reservoir. The interference between two doublets that are separated by a fault has not been previously studied for DUGS. In this work considering subsurface uncertainty in a full factorial design using 5184 3D reservoir simulations we show that a fault can reduce the system lifetime of a two-doublet system by more than 40 % if one doublet is at close proximity to it. Further, we identify that the fault can also improve both the system lifetime and generated Net Present Value (NPV) with appropriate development decisions. Contrary to previous results that did not consider reservoir architecture, a tramline well configuration is preferable when the doublets have the fault in the centre, while a checkerboard configuration is preferable as the distance to the fault decreases. The Heat In Place (HIP) recovery shows a linear relationship with flow rate and well spacing that is not affected by the fault distance or flow properties. The dimensions of the Influence Area (IA) previously considered are insufficient to capture the temperature drop at the producer wells and the fault position can increase this discrepancy. Our results show the importance of fault characterisation and well positioning with respect to a fault considering subsurface uncertainty and how this can affect denser field development of DUGS. Our findings suggest to integrate faults and the relative positioning of well doublets with respect to a fault more strongly in field development plans. Such considerations should also be included in future optimization plans of multi-well geothermal systems. Moreover, the regulatory framework should be revised to achieve a better match between the IA boundary and the production well temperature drop to enable better planning for denser development of DUGS.

Budded baculoviruses as a receptor display system to quantify ligand binding with TIRF microscopy.

Studying mechanisms of receptor-ligand interactions has remained challenging due to several limitations of different measurement methods. Here we present a total internal reflection fluorescence microscopy-based method that maintains the right balance between retaining the receptors in the natural lipid environment, sufficient throughput for ligand screening, high sensitivity, and offering more detailed view into the ligand-binding process. The novel method combines G protein-coupled receptor display in budded baculovirus particles and the immobilization of the particles to a functionalized coverslip. We adapted and validated the functionalized coverslip preparation process to achieve selective immobilization of budded baculovirus particles. The selectivity of budded baculovirus immobilization was validated with budded baculovirus particles displaying either Frizzled 6 receptors labeled with mCherry or neuropeptide Y Y1 receptors. To scale the system for ligand binding assays, we developed both open-source multiwell systems and image analysis software SPOTNIC for flexible assay design. The neuropeptide Y Y1 receptor was used for further receptor-ligand binding studies with high-affinity TAMRA labeled fluorescent ligand UR-MC026. The affinities of the fluorescent ligand and four unlabeled ligands (BIBO3304, UR-MK299, PYY, pNPY) were obtained with the developed method and followed a similar trend with both the parallel measurements with fluorescence anisotropy method and the data published earlier. The novel method could be extended for various advanced assays utilizing multidimensional detection modes, integrating super-resolution methods for single molecule detection and microfluidic devices for kinetic measurements.