Fluid Withdrawal Research Articles

Analytical solution to the problem of injection or reduction of the formation pressure in the reservoir with a fracture

The problem of injection of Newtonian fluid at a constant flow rate through an injection well into an initially undisturbed infinite reservoir with an erosive vertical main fracture of constant width is considered. Using the Laplace transform method, analytical solutions are obtained for the pressure fields in the fracture and reservoir, the flow velocity in the fracture, as well as the equations for fluid trajectories in the reservoir and in the main fracture are derived. The solutions obtained are also applicable to the problem of fluid withdrawal into a production well intersected by a vertical main fracture. Nonstationary two-dimensional pressure fields in the reservoir, as well as the pressure and velocity fields in the fracture, are constructed.

Dredged Canals, Wetland Loss, and Legacy

AbstractThe direct effects of converting coastal wetlands to open water by dredging them can be magnified by indirect effects. For example, dredged canals allow for recovery of mineral fluids 1000 s of m belowground which may induce geological subsidence or faulting; the dredged material deposited at the surface creates levees that redirect overland water flows. These indirect factors may stress wetland plants enough so that additional wetland habitat is converted to open water as a result of longer intervals of wetland soil waterlogging and drying, sulfide toxicity, less organic matter and sediment accumulation, and greater erosion. We quantified the indirect effects by demonstrating a robust dose–response relationship between coastal land loss and canal density in the Mississippi and Niger river deltas over 5 decades. Importantly, the ratio of land loss to canal area increases with time—a legacy effect. Surface impediments to water movements rather than belowground subsidence are the dominant causal factor. We also found that flood protection levees on the main river channel did not significantly magnify the effect of dredging on wetland loss. The cumulative effect of these direct and indirect consequences in coastal Louisiana is enormous and continuing, equaling many tens of billions dollars annually. Understanding these effects supports the rejection of a hypothesis that regional river channel flood protection levees or fluid withdrawal is of greater importance than the local changes in wetland hydrology. Wetland restoration/mitigation of dredging impacts on these two coasts can be implemented at a relatively low cost and quickly if this paradigm of the causes of coastal wetland losses is adopted.

Hemodynamic management of acute kidney injury.

To discuss the role of hemodynamic management in critically ill patients with acute kidney injury. Acute kidney injury (AKI) may be associated with persistent alterations in renal perfusion, even when cardiac output and blood pressure are preserved. The effects of interventions aiming at increasing renal perfusion are best evaluated by renal Doppler or contrast enhance ultrasound. However, limited data have been acquired with these techniques and the essential of the literature is based on surrogates of renal function such as incidence of use of renal replacement therapy. Fluids may increase renal perfusion but their effects are quite unpredictable and can be dissociated from their impact on cardiac output and arterial pressure. Inotropes can also be used in selected conditions. At the de-escalation phase, fluid withdrawal should be considered. Safe fluid withdrawal may be achieved when applied in selected patients with preserved tissue perfusion presenting signs of fluid intolerance. When applied, stopping rules should be set. Dobutamine, milrinone and levosimendan increase renal perfusion in AKI associated with cardiac failure or after cardiac surgery. However, the impact of these agents in sepsis is not well defined. Regarding vasopressors, norepinephrine is the first-line vasopressor agent, but vasopressin derivative may limit the requirement of renal replacement therapy. Angiotensin has promising effects in a limited size post-Hoc analysis of a RCT, but these data need to be confirmed. While correction of severe hypotension is associated with improved renal perfusion and function, the optimal mean arterial pressure (MAP) target level remains undefined, Systematic increase in MAP results in variable changes in renal perfusion. It sounds reasonable to individualize MAP target, paying attention to central venous and intraabdominal pressures, as well as to the response to an increase in MAP. Recent studies have refined the impact of the various hemodynamic interventions on renal perfusion and function in critically ill patients with AKI. Though several of these interventions improve renal perfusion, their impact on renal function is more variable.

Pressure Transient Solutions for Unbounded and Bounded Reservoirs Produced and/or Injected via Vertical Well Systems with Constant Bottomhole Pressure

Various analytical solutions for computing production and injection-induced pressure changes in aquifers and oil reservoirs have been derived over the past century. All prior solutions assumed a constant well rate as the boundary condition. However, in many practical situations, the fluid withdrawal from and/or injection into such subsurface reservoirs occurs with the aid of pump devices that maintain a constant bottomhole pressure in the well. Until now, how the well rate will decline over time, based on the pressure difference in the well relative to the initial reservoir pressure, could not be rapidly computed analytically (using the diffusivity as the key governing system parameter), because no concise expression had been derived with the boundary condition of a constant bottomhole pressure. The present study shows how the pressure diffusion equation can be readily solved for wells acting as sinks and sources with a constant bottomhole pressure condition. We consider both fractured and unfractured completions, as well as injection and production modes. The new solutions do not require an elaborate time-stepped pressure-matching procedure as in nodal analysis, the only other physics-based analytical method currently available to compute the well rate decline when a constant bottomhole pressure production system is used, which unlike our new method proposed here is limited to single well systems.

Operation of downhole pumps under sanding conditions

One of the unfavourable factors of downhole pumping equipment operation at the fields at the final stage of development is high content of mechanical impurities in the pumped fluid. Similar problems are observed in fields with friable, weakly cemented formations, the fracture products of which flow downhole, resulting in lower extraction rates, equipment damage and higher operating costs. In oil production practice various technological measures and technical means are used to reduce the negative impact of sand penetration - regulation and optimisation of pumping equipment operation mode to ensure a rational rate of fluid withdrawal, application of technical devices in the form of sand filters and sand anchors and others. However, these measures and recommendations, for the most part, work successfully in the modes of continuous operation of wells. With the growing number of oil fields at the final stage of development, the issue of sanding becomes more and more urgent, as due to low flow rate wells at such fields are often switched to the mode of periodic operation, which favours the formation of sand plugs in tubing above the pump due to sufficient time for sedimentation of mechanical impurities. This can lead to pump jamming or rod breakage during subsequent well pump start-up. The experience of using sand filters (frame, slotted and others) in the arrangement of downhole pumps has shown that it does not always effectively solve the problem of sand penetration due to clogging of their cells with mechanical impurities and increased hydraulic resistance. This negatively affects the pumping equipment operation due to the shift of characteristics into the zone of suboptimal modes with associated problems for the electric drive. This makes it necessary to carry out underground well workover with removal of deep well pumping equipment for replacement or washing of the filter in surface conditions, as due to their peculiarities in the well pump layout (the filter is located at the intake of the pumping section), washing in well conditions is not always possible. These problems require not only the creation of effective downhole devices to prevent sand ingress to the pump intake or devices to prevent sand plugs above it, but also acceptable in practice calculation methods for predicting the sedimentation time of mechanical impurities in tubing or determining the minimum required speed of upward oil flow for stable sand removal. These calculation methods would also allow to reasonably regulate the time of technological interruptions while waiting for the wells to start up in periodic operation modes or to predict the time of activation of sand control devices for discharging the sand accumulated above the pump. This is the subject of this article. As a result of calculation analysis it was established that the main factors affecting the sedimentation process of mechanical impurities in the well are the speed and mode of fluid movement, its viscosity, density and size of the impurities themselves. Moreover, the most sensitive for the calculation accuracy is to take into account the change of fluid viscosity as it moves along the tubing as a result of heat exchange and the change of dissolved gas content due to pressure drop. Although at this stage the proposed methodology does not take into account some factors that can make additional adjustments to the process of sand sedimentation, however, it allows to predict with acceptable accuracy the time of technological interruptions in the well operation to prevent the formation of sand plugs, or the rational mode of operation of pumping equipment, providing the necessary speed of upward flow in the pipe for sand removal.

Examination of Particulate Contamination in Parenteral Injections and Infusions Following Fluid Withdrawal Utilizing Conventional Needles and Filter Needles: Assessment of Compliance and Comparative Analysis

Particulate contamination, the unintentional presence of particles in parenteral fluids, is associated with potential risks such as phlebitis and thrombophlebitis. Recent guidelines recommend the use of filter needles when withdrawing parenteral fluid from vials with a rubber stopper. However, the literature is limited and lacks clarity regarding the advantages of filter needles over conventional needles. The aim of this study was to assess the compliance of parenteral fluids regarding particulate contamination after withdrawing fluid using both conventional needles and filter needles, following the guidelines of European Pharmacopoeia (Ph. Eur.) and United States Pharmacopoeia (USP). Visible particles were counted through visual inspection and sub-visible particles were quantified utilizing the light obscuration particle count test. Particle counts for both types of needles were compared to Ph. Eur. and USP standards and differences in particle contamination were assessed using a Mann-Whitney U test. Both types of needles demonstrated compliance with Ph. Eur. and USP standards regarding particulate contamination of visible and sub-visible particles. However, filter needles exhibited a significantly higher particle count for particles with a size of ≥25 µm compared to conventional needles (p = 0.0029). In conclusion, both types of needles demonstrate suitability for aspirating fluid from vials featuring rubber stoppers regarding particulate contamination. Nevertheless, non-filter needles are preferred for withdrawing fluid from vials with a rubber stopper over filter needles due to their lower cost.

A novel approach for geomechanical modelling in the absence of stress magnitude data

Geomechanics play an important role in any underground activity, such as carbon dioxide (CO2) and hydrogen (H2) geo-storage, owing to the considerable hazards linked to the injection and withdrawal of fluids into and from the subsurface. In order to quantify these risks, knowledge of full stress tensor is required. Yet, most of our stress information in the Australian target basins for geo-storage is limited to the stress orientations, while stress magnitude data is sparse. 3D geomechanical modelling has proved to be an invaluable tool for prediction of full stress tensor. Nevertheless, a model requires some stress magnitude data in order to tune the model to be representative of real stress state. In situations where stress magnitude data is lacking, this means that the model is susceptible to significant uncertainties. Herein, we present a novel strategy for stress modelling, which involves the utilisation of indirect data such as borehole breakouts, drilling-induced fractures, seismic activity records, and formation integrity tests to calibrate a 3D geomechanical model. We employ the northern Bowen Basin, an onshore basin in Queensland, Australia, as a case study for a comprehensive 3D geomechanical modelling approach. We assess all the indirect information in the model’s volume to narrow down the model predictions and find the most reliable stress state. This innovative approach is an important step forward in stress modelling of Australian basins, where lack of stress magnitudes is a great challenge for geomechanical assessment of geo-storage.

Temporal evolution of demarcations between the unsteady and steady regions and between the film and meniscus during dip coating with vertical withdrawal of Newtonian fluids

Thus far studies on dip coating focus on the asymptotic layer thickness which is reached only in the lower part of the layer when the withdrawal time is sufficiently long. This work attempts to offer a complete description of the evolution of layer thickness profile with withdrawal time for vertical withdrawal of Newtonian fluids using simulation and the Buckingham π theorem. The results show that over time, the withdrawal process successively undergoes two regimes: (I) an unsteady film region and an unsteady meniscus region and (II) an unsteady film region connected to a steady meniscus region through an unsteady meniscus region. The controlling factors for the two regimes are identified at different values of capillary number and Reynolds number. Models are proposed to predict the heights of the demarcations between different regions. The models agree well with experimental results when the controlling forces are viscous force and gravity.

MAPPING AND PREDICTION OF LAND SUBSIDENCE

The exact location and timing of a land subsidence-related calamity cannot be foreseen with any degree of confidence. This is true for both progressive subsidence caused by fluid (groundwater, oil or gas) withdrawal and abrupt subsidence on surface caused by underground mine collapse. The best way to deal with these dangers is to mitigate them. In an ideal world, all regions prone to such risks would be well-known, and measures would be made to either prevent causing the problem if it is human-caused, or to avoid inhabiting such areas if they are prone to natural subsidence. Extensometers, levelling, hydrogeology modelling, and GPS are common methods for monitoring subsidence, although they require precise field data and are time-consuming. PSI (Persistent Scatterer Interferometry) is a strong radar-based remote sensing technique for measuring and monitoring surface displacements over time. The techniques of PSI using microwave sensors has made monitoring of earth deformation precisely more reliable and generates large number of Persistent Scatterer Candidates (PSC’s) or sampling points. Although, all the above techniques have their own merits and de-merits but mapping and prediction of susceptible subsidence prone zones is an issue. This paper deals with the application of the Exploratory Data Analysis (EDA), a powerful environment in Data Science provided a set of tools that made it easier to interpret PSI processed Big Data and also improved the capability of validation, management, visualization, and presentation of results with greater reliability.

A one-way coupled geomechanical model for CO2 storage in faulted depleted gas reservoirs

Robust geomechanical models are critical for predicting and monitoring challenges associated with fluid injection and withdrawal in different operations, including underground gas storage. However, little attention has been given to geomechanical modeling and responses of faulted structures in the context of CO2 storage. In this study, a one-way geomechanical model was developed for a depleted gas field in the Bredasdorp Basin in South Africa and coupled with a dynamic model to gain insights into the geomechanical challenges associated with CO2 storage in faulted depleted gas fields. Three geomechanical deformation scenarios were formulated to evaluate the behaviour of the gas field. The results obtained indicated a substantial contrast in the stress state between the central and peripheral regions of the reservoir. Moreover, during the depletion phase, the reservoir experienced a subsidence of 3 cm, while 1.8 cm was observed during the injection phase. It was also found that the uplift of the underburden compensated for the loss of fluid support, enabling the reservoir to uphold the overlying overburden despite depletion. However, after 40 years of CO2 injection, the caprock failed while the reservoir rock remained stable. Furthermore, depletion increased the likelihood of fault slip, while CO2 injection significantly reduced deviatoric stresses and indirectly minimized the tendency for fault activation. It seems that the one-way coupled model can provide valuable insights into the poromechanical response of the faulted depleted gas field used for CO2 storage, although the results presented in this study may need further calibration against the field data.

Subsurface deformation monitoring with InSAR and elastic inversion modeling in west Texas

Recent Interferometric Synthetic Aperture Radar (InSAR) observations depict centimeter-level surface uplift/subsidence signals in west Texas that correlate spatially and temporally with increased fluid extraction and injection activities over the past decade. Linear subsidence features from InSAR data near the Pecos area, that align well with maximum horizontal stress orientations and recent clusters of seismic events, suggest fault motion is also associated with this deformation. In this study, we investigate the relationship between observed surface displacement and inferred subsurface fault slip and reservoir compaction/inflation by inversely solving a combined model of elastic dislocation (Okada, 1985, 1992) and poroelastic reservoir compaction/inflation model (Geertsma, 1973).Our geomechanical analysis coupled with InSAR observations are consistent with the idea that both fault slip and reservoir inflation/compaction are occurring associated with fluid injection and withdrawal in the Pecos area. Numerical results show that the linear surface displacement patterns can be accurately reproduced using clusters of finite slip on multiple elastic dislocations in the subsurface, but also matching the broader areal subsidence and uplift signals requires the addition of poroelastic subsurface inflation and depletion. The inverted areal reservoir pressure distribution correlates well with known injection and withdrawal operations in the area. The best-fit surface deformation locates most fault slips patches at depths of 1–3 km, which is shallower than most reported earthquakes in this area. The difference in the estimation of depth suggests there could be aseismic fault slippages.

A New Analytical Method for Calculating Subsidence Resulting by Fluid Withdrawal from Disk-Shaped Confined Aquifers

This work presents the derivation of analytical solutions concerning the radial subsidence distribution ensuing from fluid extraction from a disk-shaped confined aquifer in homogeneous formations. The study draws upon methodologies developed in petroleum geomechanics of deep reservoirs to estimate surface uplift due to CO2 injection using Hankel-transformed thin plate theory. These methods yield simplified expressions as compared to previous results derived using the superposition principle on surface uplift from a uniform pressure field. Hence, closed-form formulas for the subsidence at the well location are re-derived, while the formulas for the subsidence field are deducted by both methods and the mathematical relation between the two methodologies is discussed. Additionally, innovative closed-form asymptotic solutions for radial subsidence distribution are deduced for scenarios involving deep aquifers. These solutions demonstrate exceptional accuracy when aquifer depth exceeds aquifer diameter, exhibiting independence from formation permeability and fluid viscosity. The study explores the influence of physical parameters on the subsidence field.

The parameter inversion in coupled geomechanics and flow simulations using Bayesian inference

In many situations, uncertainty about the mechanical properties of surrounding soils due to the lack of data and spatial variations requires tools that involve the study of parameters by means of random variables or random functions. Usually only a few measurements of parameters, such as permeability or porosity, are available to build a model, and some measurements of the geomechanical behavior, such as displacements, stresses, and strains are needed to check/calibrate the model. In order to introduce this type of modeling in geomechanical analysis, taking into account the random nature of soil parameters, Bayesian inference techniques are implemented in highly heterogeneous porous media. Within the framework of a coupling algorithm, these are incorporated into the inverse poroelasticity problem, with porosity, permeability and Young modulus treated as stationary random fields obtained by the moving average (MA) method. To this end, the Metropolis–Hasting (MH) algorithm was chosen to seek the geomechanical parameters that yield the lowest misfit. Numerical simulations related to injection problems and fluid withdrawal in a 3D domain are performed to compare the performance of this methodology. We conclude with some remarks about numerical experiments.

Causal mechanism of Gotthard Base Tunnel-induced ground deformation: Insights from 3D fully-coupled hydro-mechanical simulation and comparison to field measurements

The Gotthard Base Tunnel (GBT), constructed between 2000 and 2011, is a 57 km long and up to 2.5 km deep high-speed railway tunnel located in the Swiss Alps. Significant ground surface displacements reaching about 10 cm were observed during and after the tunnel construction. To gain a better understanding of the causal mechanism of such conspicuous ground deformations, we develop a three-dimensional (3D) fully-coupled hydro-mechanical model to simulate GBT-induced groundwater drainage, stress redistribution, rock mass consolidation, and fault zone deformation at the regional scale. First, we construct a geological model with topographical features, lithological units, and natural faults realistically represented. We constrain the material properties of fault zones and rock masses based on available extensive laboratory testing results and site characterisation datasets. We then simulate the tunnelling process over time, with the resulting coupled hydro-mechanical responses of faulted rock masses well captured and ground surface/subsurface displacements quantitatively analysed. The simulation results in general show a good agreement with the field monitoring data of ground surface displacement, subsurface tunnel settlement, and groundwater inflow into the tunnel. Our model indicates that ground surface displacements originate from GBT-induced water drainage and rock mass consolidation in the deep subsurface. Our results also show that the GBT construction could trigger faults to shear via drainage-induced pressure diffusion and poroelastic stressing. The research findings from our work have important implications for many groundwater drainage-related geoengineering activities such as underground excavation in alpine mountains and fluid withdrawal in subsurface reservoirs.

Workflow for the Validation of Geomechanical Simulations through Seabed Monitoring for Offshore Underground Activities

Underground fluid storage is gaining increasing attention as a means to balance energy production and consumption, ensure energy supply security, and contribute to greenhouse gas reduction in the atmosphere by CO2 geological sequestration. However, underground fluid storage generates pressure changes, which in turn induce stress variations and rock deformations. Numerical geomechanical models are typically used to predict the response of a given storage to fluid injection and withdrawal, but validation is required for such a model to be considered reliable. This paper focuses on the technology and methodology that we developed to monitor seabed movements and verify the predictions of the impact caused by offshore underground fluid storage. To this end, we put together a measurement system, integrated into an Autonomous Underwater Vehicle, to periodically monitor the seabed bathymetry. Measurements repeated during and after storage activities can be compared with the outcome of numerical simulations and indirectly confirm the existence of safety conditions. To simulate the storage system response to fluid storage, we applied the Virtual Element Method. To illustrate and discuss our methodology, we present a possible application to a depleted gas reservoir in the Adriatic Sea, Italy, where several underground geological formations could be potentially converted into storage in the future.

Interdialytic weight gain levels and blood pressure changes during fluid withdrawal in hemodialysis patients

Introduction: interdialytic weight gains (IDWG) are a secondary impact of excessive fluid and/or food intake. In addition, IDWG is common in hemodialysis patients due to renal excretion dysfunction, which impacts fluid buildup. Interdialytic Weight Gain (IDWG) is a secondary impact of excessive fluid and/or food intake and is common in hemodialysis patients due to renal excretion dysfunction. If the patient has severe IDWG, it will have an impact that fluid withdrawal will be increased. This increases the risk of complications during fluid withdrawal on hemodialysis. Objective: to identify the relationship of IDWG levels with changes in blood pressure during fluid withdrawal in hemodialysis patients. Materials and Methods: this was a descriptive-analytic study in which 90 patients undergoing HD were recruited using consecutive sampling. Respondents are free to get involved and withdraw from research and respondents who are involved in research are given rewards from researchers. Result: the study found a relationship between IDWG and blood pressure changes during fluid withdrawal during the 1st hour (P value < α; α = 0.05). Discussion: blood pressure changes during hemodialysis primarily increased blood pressure influenced by some factors. The factors are IDWG levels, UF volume, stimulation of the Renin-Angiotensin-Aldosterone System, antihypertensive therapy, and history of cardiovascular disease. The limitation of this study is that blood pressure measurements on some respondents were not carried out on time, because respondents sometimes fell asleep. Conclusion: based on this study, IDWG is related to changes in blood pressure at the 1st hour of fluid withdrawal.

ANALYSIS OF EFFICIENCY OF HORIZONTAL WELLS WITH MULTI-STAGE HYDRAULIC FRACTURING ON THE EXAMPLE OF KONDINSKOYE FIELD

In the structure of potential oil reserves in Western Siberia, the share of hard-to-recover reserves (HRR) is growing. At the same time, a significant share of these reserves is concentrated in low-permeability reservoirs. Horizontal wells using multi-stage hydraulic fracturing are the basis of technological solutions used for cost-effective development of low-permeability reservoirs by Russian oil and gas producers [1-4]. Due to the high efficiency of the subsea development systems with MSHF, oil production from such facilities exceeds oil production from traditional reservoirs and accounts for more than 60 % of the total oil production of the Company's fields [5]. The following characteristics are identified as the key parameters of the horizontal section, the number of hydraulic fractures, as well as the specific weight of the injected proppant at the frac stage. The decisions approved as part of the design documents for the development of facilities with TPP indicate a tendency to increase the length of the horizontal hole and the number of frac operations with a decrease in the specific mass of proppant on the port. The article examines the impact of these characteristics on the technological efficiency of wells. The purpose of the work is to assess the feasibility of increasing the technological complexity of HW with multi-stage hydraulic fracturing of the MSHF formation in the form of increasing the number of stages and length of the horizontal hole, as well as the specific mass of proppantane in the example of the AS10/1 Kondinskoye field development target. Within the framework of the study, three types of HW with MSHF were identified, the technological effectiveness of which was assessed in two ways. The first method consisted in comparing the magnitudes of the dimensionless productivity coefficient Jd (d. units) of three different types of wells with a horizontal end in relation to directional wells (FWS with frac) of the environment. Taking into account the similarity of the geological conditions of the neighboring wells, this method made it possible to assess how effectively the completion of the horizontal wells under study was completed. The multiplicity assessment methodology was developed by RN-BashNIPIneft LLC [6]. The second method was to compare the ratio of dimensionless productivity factor to the specific weight of proppant Jd/Mpr _ specific of the identified types of HW with multi-stage hydraulic fracturing (MSHR). This approach made it possible to take into account the effective thickness and permeability of the formation in the well drilling zone, as well as the weight distribution of the injected proppant. The results showed that if the length of the horizontal hole is constant, an increase in the number of frac stages while reducing the proppant weight on the port is impractical. Confirmation was also obtained based on statistical data that there is a relationship between the cumulative fluid withdrawal and the weight of the injected proppant. It has been established that drilling HW with multi-stage hydraulic fracturing of the (MSHF) formation of the most common type (1000 m, 10 stages) is not optimal for the study target: for a length of 1000 m, the maximum number of stages should be limited to 7–8 units per well. Further monitoring and analysis of production wells with horizontal termination is recommended to collect more statistical data and compare them over time.

Fluid Flow to a Well through a Radial Hydraulic Fracture in a Porous Medium at Constant Flow Rate

The problem of fluid withdrawal from a reservoir into a well or injection of fluid from a well into a reservoir in the presence of a hydraulic fracture perpendicular to the wellbore is considered in the constant flow rate regime. Analytical solutions that describe the evolution of pressure in the fracture at a constant reservoir-to-well fluid flow rate are obtained. Approximate solutions are constructed using the method of successive change of stationary states (SCSS). A comparison of the numerical results of the exact and approximate solutions shows that these solutions are almost identical. The influence of the reservoir features of the stratum and fracture on the evolution of pressure in the fracture and well is analyzed.

Effect of Seepage Velocity on Pore Clogging Growth Behavior and Its Effect on Permeability Reduction During Fines Migration in Porous Media

AbstractFines migration driven by fluid flows often causes pore clogging in porous media and thus reduces the permeability of the porous media. The clogging can pose serious problems in various practices, such as formation damage in hydrocarbon reservoirs, degradation of fluid withdrawal or injection efficiency, particle‐induced fouling in filtration membranes, or even a risk of sediment failure with geostructures. However, the effect of seepage flow velocity on the spatial growth pattern of fines‐induced pore clogging remains poorly identified. This study explores the pore clogging growth behaviors caused by flow‐driven fines migration and accumulation in porous media and the associated permeability reductions through a series of column experiments and concurrent X‐ray computed tomography imaging. Particularly, the X‐ray image analysis captures the spatial distributions of fines, and thus the homogeneous or heterogeneous (localized) clogging growth pattern under various seepage velocities. Our results reveal that an increase in the seepage flow velocity increases the likelihood of localized clogging growth, attributable to the direct interception of fines by the sand grains. The localized clogging growth causes a faster reduction in permeability than the homogeneous clogging growth. The presented study provides well‐controlled experiment data on fines distribution and associated permeability change, which gives insights into fines‐induced clogging behavior in porous media.

The study of efficiency of increase of fluid production in long-term developed fields

As is known, one of the most effective methods of increase of oil development for the mature production fields is the forced fluid withdrawal (FFW). In this respect, the bypassed oil, lenses, blind and dead zones, and low-permeable interlayers are involved in the development of non-homogeneous and heavily watered formations. The decision on the employment of FFW should be made only after the study of the correlation between the flow rate of oil, water, fluid, as well as the water cut. With the purpose of the evaluation of the efficiency of FFW application, the researches based on the actual field data of the well operation in Lokbatan and Gala fields of “Azneft” PU have been carried out. Thus, the dependencies of the flow rate of oil, water and water cut of the product on the flow rate of fluid by all reviewed wells have been developed on a system approach and analyzed, as well as the mathematical models have been found. The analysis and estimation calculations justified the capacity of an approximately 7 % increase of oil production due to the forced withdrawal by the reviewed pattern of wells in Gala field. The studies conducted on the field data justify the practicability of the employment of forced fluid withdrawal in the wells operated from the upper stage of Productive Series in Gala field.