查看更多>>摘要：Low salinity waterflooding has been reported to yield incremental oil recovery from both field applications and laboratory experiments compared to regular waterflooding. Crude oil-brine-rock (COBR) interactions dictate wettability alteration during low salinity waterflooding in sandstones. In this work, triple-layer surface complexation modelling (TLM) is utilised to simulate the interactions at rock-brine and oil-brine interfaces, while accommodating the crucial role of sandstone mineralogy in surface chemistry. Derjaguin-Landau-Verwey. Overbeek (DLVO) theory is applied to characterise the COBR stability. Moreover, we propose the use of the maximum energy barrier (MEB) parameter, which is calculated from the DLVO theory's interaction potential, as an indicator of reservoir wettability. Correlating the MEB with the experimentally measured contact angles revealed an abrupt increase in contact angles as the MEB drops below the zero-value thereby leading to a less water-wet COBR system. Results analyses showed that the different clays affect the rock-brine zeta potential and wettability distinctly based on their surface site densities and specific surface areas. And the studied clays cause the zeta potential to become more negative in the order: smectite > montmorillonite > illite > chlorite > kaolinite. Subsequently, further investigation employing the developed TLM and MEB revealed that higher amounts of kaolinite will make the reservoir more oil-wet. Lastly, the sensitivity analysis performed on reservoir wettability indicated that the ionic composition is the most important factor to affect rock wettability followed by pH and temperature. Moreover, the presence of CaCl2 salt in the formation water significantly supresses the areas of strong water wettability under varying reservoir conditions compared to NaCl salt. The work conducted in this study presents a novel approach to model the individual and combined effects of sandstone minerals, specifically, quartz, kaolinite, chlorite, illite, montmorillonite and smectite, on the overall sandstone zeta potential behaviour. Furthermore, a new method was proposed to characterise reservoir wettability as a function of the maximum energy barrier which allowed us to obtain valuable insights into the most affecting reservoir parameters on COBR wettability. These findings will have practical implications to efficiently design the low salinity waterflooding processes for sandstone reservoir applications.
Mohammad ParvazdavaniMohammad Reza Khorsand MovagharS. Ali Mousavi Dehghani
22页
查看更多>>摘要：Enhancing the oil recovery of carbonate reservoirs with acidic oil depends on injected brine composition and salinity throughout the low salinity water flooding. The typical description of this phenomenon on oil and water relative permeability curves is being put forward by the process-dependent interpolation function, which barely addresses the underlying fundamentals governing the direct impact of wettability alteration and geochemical reactions on flow saturation functions. The main objective of this work is to perform an integrated investigation of the effect of salinity on oil and water relative permeability curves by dynamic coupling of the Derjaguin, Landau, Verwey, and Overbeek (DVLO) theory and geochemical reactions. We studied both the single and two-phase systems using the basis of the geochemical reactions to track the variations of the wetting and non-wetting phase relative permeability curves. In the single-phase scenario, the results show the superiority of the reactive flow modeling technique with kinetic-controlled reactions, in the range between [2-4] of the Damkohler number, to yield a better result for the experimental effluent ions' concentrations than the equilibrium approach. In addition, the single-phase results under dynamic conditions propose Civan correlation as the best predictor of residual resistance factor (RRF) by numerically adjusting the correlation of coefficients based on the physical variables - salinity, dimensionless consumed ion concentration, and Peclet number. Accordingly, the results indicate a novel linkage between the single-phase and two-phase results in the sense that RRF under single-phase mode can be used to estimate the change in the wetting phase relative permeability under the two-phase mode. The single-phase methodology provides the capability for an improvement - up to 15% - in die prediction of the pressure drop curve. For two-phase cases, our procedure involved coupling the characterized geochemical reactions and the DLVO theory to consider the effect of injected water composition on contact angle as the static two-phase parameter. The phase-field method is coupled with DLVO theory to calculate the relative permeability curves for the non-wetting phase, which corresponds to the contact angle at each simulation time step. The two-phase results indicate an improvement - up to 30% - in the prediction of the recovery factor curve, on a history-matching basis, using the DLVO theory with contact angle-dependent correlation of non-wetting phase relative permeability curve. The main novelties of this study are using the single-phase dynamic permeability impairment results in calculating the variation of the wetting-phase relative permeability curve. Moreover, dynamic coupling of DLVO and non-linear contact angle-dependent correlation is used to calculate the non-wetting phase relative permeability curve. According to these novelties, more accurate prediction of the laboratory production profiles can be obtained.
查看更多>>摘要：To improve the effectiveness of mathematical modeling, analysis, control, regulation and optimization of oil field development, it is very important to have the appropriate information support. To this aspect well testing is a necessary data source. One of the most actual well test data analysis instrument is deconvolution (single-well and multi-well). The principle of superposition is implemented in the theory of well test interpretation using convolution, which makes it possible to take into account the influence of well production (or wells) history on the studied section of the bottom-hole pressure change curve. Reverse convolution or deconvolution makes it possible to derive an equivalent bottom-hole pressure curve under an unknown filtration model, which will be a reservoir 'response' to the well production at the constant rate, being equivalent to a changing well rate production. It makes it possible to 'eliminate' the changing well rate influence on bottom-hole pressure curve and identity interpretation flow model. The main disadvantage of single well deconvolution is the condition of well interference absence. To overcome this constraint a multi-well deconvolution is applied. Its main purpose is to assess the interference of wells and to determine the inter-well filtration-capacitive properties. In common case multi-well deconvolution task solution is a labour-intensive process. The main limitation of known approaches application to multi-well deconvolution is assumption of constant filtration model (also actual for single well deconvolution). It makes impossible its application to producing wells with increasing water-cut analysis. Instead, it is possible to go to an equivalent task and describe the wells interference using a modified CRM-model. Therefore, the article proposes a specially modified CRM-model, which can be used as an analogue to bottom-hole pressure and well rate data multi-well deconvolution for wells with increasing water-cut. The CRMsim-model is taken as the initial model for further modification. Unlike to the CRMsim-model, in the present case, the accounting of the water-cut is based on historical data by modifying the productivity index. In total 6 different modifications were proposed. This concept is tested on synthetic data and on field data from an oil field in the Timan-Pechora province. Testing on the synthetic example shows good results. In the case of the real field example, the results acquired after multi-well deconvolution application to well with increasing water-cut by 6 proposed models were compared to well test results of zero water-cut production period. Evaluated filtration-conductivity properties are of high reliability degree for zones adjacent to well and reservoir between wells, pressure interference of every well has been identified according to tested well production data. This approach is a reasonable alternative to the multi-well deconvolution, which is not applicable to changing flow model of well with increasing water-cut.
查看更多>>摘要：Microorganisms have different benefits including bioremediation of aquifers contaminated with the non-aqueous liquid phase, microbial EOR, and bacterial degradation of asphaltenes. Despite these profits, a special kind of bacteria named Sulfate Reducing Bacteria (SRB) causes H2S generation which is toxic and also results in equipment erosion and corrosion. The injected water approaches the production well in a radial form geometry. However, less is known about the H2S generation and movement in the radial coordinate. In this study we investigated SRB souring in aquifers and oil reservoirs using a reactive numerical simulation of multicomponent and multiphase radial flow. The operator-splitting method was utilized to model this dispersion-dependent phenomenon. Furthermore, a higher-order finite difference approach was adopted to more accurately model SRB souring by avoiding the numerical dispersion. The results of the proposed approach were verified with the existing analytical radial solution by applying the simplifying assumption of the analytical radial solution. Also, the effect of numerical and physical dispersions was evaluated and it was highlighted that under certain conditions numerical dispersion can be confused with the physical one. Moreover, a comparison of the H2S profile in the radial coordinate with linear geometry showed significant differences which should be considered in SRB souring studies. This difference highlights the necessity of radial grid refinement around the wells in full-field reservoir simulation to attain more accuracy. The study of SRB souring during water injection in an oil reservoir also illustrates the same pattern as souring in aquifer but the oil presence delays mixing between sea and formation water and postpones H2S generation. The findings of this work provide a better understanding of near-wellbore SRB souring during water injection in porous media.
查看更多>>摘要：The rapid growth of artificial intelligence (AI) technology and its applications in recent years has transformed the process of data analytics in many scientific fields, including geoscience. Geoscience has traditionally been a descriptive science and fundamentally relies upon visual recognition and identification of different geological features, from satellite images to subsurface seismic, to study Earth's history. Geological image data provides immense potential to apply advanced AI methods, such as deep learning to improve and optimize different geological and geophysical characterization workflows. Despite the increasing efforts and interest toward using AI in geosciences, its actual potential remains untapped, and further exploration is required. The prospect of AI application in geosciences is primarily hindered by the following: (i) limited availability of high-quality labeled datasets and (ii) inherited imbalance dataset distribution. These limitations are compounded by overexploitation of the transfer learning method to mitigate such issues, discarding the interpretability of the AI black-box problems. In this study, a robust and effortless strategy is proposed to overcome the limitations and simultaneously reduce our dependency on to the transfer learning method. Among the various methods available to mitigate these issues, only traditional data augmentation is heavily used in geosciences. This study, therefore, explored and developed a workflow by combining three readily available methods to maximize the performance of machine learning algorithms when dealing with a limited and imbalanced geoscience dataset. Here, the proposed method follows three robust and straightforward end-to-end steps: (i) combining traditional and advanced data augmentation (e.g., CutOut and CutMix) techniques to enhance localization and generalization performance; (ii) employing an algorithm-level class weight method to minimize detrimental impact and performance bias due to class imbalance; and (iii) applying a regularization label smoothing technique to improve the generalization and avoid overconfident prediction. Across the study datasets, the overall accuracy is typically improved up to 12% when comparing CNN without and with the proposed strategy. In addition, when combined with transfer learning, these methods could minimize model overfitting, and optimize generalization and model performance. This study further highlights that the proposed method should apply to different applications of AI in geosciences and could provide an alternative approach to the transfer learning method in analyzing limited and imbalanced geoscience datasets and improve the interpretability of how AI models work when combined with subject matter expertise.
查看更多>>摘要：Chlorite-coats on quartz surfaces are ubiquitous in various sedimentary environments. Chlorite-coats shield the surface of quartz from quartz cement overgrowths, thus preserving anomalously high porosity in deeply buried sandstone reservoirs. The inhibition of the quartz cement implies that the chlorite-coats on the surface of quartz grains can significantly influence the physicochemical behavior of the quartz grains. Therefore, failure to notice the initial thin microscale coatings forming during deposition can have serious consequences for modeling several geochemical reactions occurring at liquid-solid interfaces. Despite this huge implication, the fundamental mechanisms involved in chlorite-coat formation is not well understood. Here we present an experimental study to determine the parameters that control chlorite-coat formation on the surface of quartz grains. The batch experiments were conducted in a concoction of quartz and chlorite under different conditions of ionic strength, pH, and presence of humic acid (HA), iron- (Fe) and aluminum (Al) oxides). HA, Fe- and Al oxides are suggested to aid the emplacement of chlorite-coat precursors. At pH 7, the quartz-chlorite and quartz-chlorite-Fe/Al-oxides mixing experiments performed in saline and non-saline solution result in equal chlorite-coat coverages, suggesting neither salinity nor Fe and Al-oxides explain the mechanisms of chlorite-coat formation. At pH 5 and 9, however the chlorite-coat coverage was superior only in saline solution, indicating differences in coat coverage may be caused by variable electrokinetic charge distribution due to the distribution and transport of dissolved salt. The chlorite-coat barely formed in experiments that contain HA in quartz-chlorite mixtures regardless of ionic strength and pH. Against a long-standing notion, the presence of organic matter cannot necessarily be prerequisites for binding chlorite on the surface of quartz grains. The dynamic interactions between solution chemistry and surface chemistry of solid phases (quartz, chlorite, HA, Fe and Al oxides) can result in changing the electrokinetic properties in a region near the solid phases and at mineral-solution interfaces. We therefore propose that the electrokinetic response that arises in heterogeneous systems may explain the mechanisms of chlorite-coat formation.
查看更多>>摘要：An interpretation for the gravity anomalies is essential to visualize the horizontal and vertical extension of the subsurface intrusion like mud diapirs resembling dike-like geologic bodies. Therefore, the use of simple-geometrical resembling models helps to validate the subsurface targets. A particle optimization algorithm is one of the recently established metaheuristic algorithms, which is utilized in various geophysical applications and allows discovering and explaining the parameters of the buried geologic targets. Here, we have interpreted gravity response profiles for mud diapir, which close an expected two-dimensional (2D) inclined dikes by calculating the following parameters; amplitude coefficient (A), depths to top (h) and bottom (H), width (2b), inclination angle (θ), origin (d), and length of the body (L) that represents the difference between two depths using the particle optimization algorithm. The stability and efficacy of this study were checked on numerical examples without noise and with numerous levels of random noise (10% and 20%). Also, it tested on a gravity response for mud diapir from the south-western (SW) Taiwan and validated by seismic interpretation. The obtained results declared that the suggested algorithm works well even in the existence of noises. Furthermore, the results of the real case model are found in a respectable agreement with available geological and borehole information and other results from the published literature.
查看更多>>摘要：The oil recovery in many carbonate reservoirs is low due to oil-wetness and heterogeneity. In this study, nanoparticles are evaluated for altering the wettability of oil-wet limestones and their properties are compared with those of an anionic surfactant. A surface-modified silica nanoparticle (SiNP) with a negative zeta potential was found to be aqueous stable in brines. Wettability studies showed that the SiNP cannot change the wettability of an initially oil-wet calcite plate, but SiNP treated calcite surface can remain water-wet after aging in oil. Spontaneous imbibition tests confirmed the observations of wettability tests and showed that a SiNP treated carbonate core retained its water-wettability during oil injection and aging. The imbibition into a SiNP treated and oil aged core was comparable to that in a water-wet core. However, SiNP was not able to remove the oil layers in initially oil-wet cores and imbibe water into these cores. In contrast, the anionic surfactant could alter the oil-wet carbonate rocks to a more water-wet condition, but failed to prevent the water-wet surface from getting oil-wet during oil-aging. The results suggest that the SiNP can be injected into wettability-altered (water-wet) reservoirs/regions to help retain the water-wettability during the long-term oil production. The 0.5 wt% SiNP dispersions transported through 18 mD limestone cores without any plugging. The SiNP retention was measured to be 2.5 mg/m~2, much higher than that of the anionic surfactant.
查看更多>>摘要：In order to apply electrohydraulic shock wave (EHS) technology to oil and gas stimulation or assisted rock fracture, it is necessary to analyze how the crack propagation behavior of the rock subjected to the EHS. For this purpose, experiments and numerical simulations are carried out respectively. In the experiment, the relevant parameters of electrical characteristics and acoustic radiation characteristics were given based on the established discharge platform, and 30 times impacts tests are carried out on cubic concrete. The results show that the corner areas of the upper surface of the concrete are the first to be broken; with the increase of impact time, the shape and number of cracks on the surface of the concrete sample change in two stages. In the first stage, the number of microcracks increased rapidly, the cracks are interconnected, and the existing pores gradually become bigger. In the second stage, the growth rate of the number of microcracks gradually decreases, and the width of the formed cracks gradually increases; the damage variable of the concrete obtained by the acoustic test increases sharply first and then increase slowly throughout the impact test. In the numerical simulation, the history match of the EHS pressure is implemented based on the equivalent explosion method (EEM); a two-dimensional numerical model is established to simulate the interaction process between the EHS and the concrete sample; a three-dimensional TNT-water-concrete numerical model is built to simulate the concrete fracturing. The results show that it is reliable to use the equivalent explosion method to simulate the EHS. The concrete sample subjected to the EHS is affected by four aspects: bubble; transmitted wave and reflected wave; diffraction wave; elastic precursor wave and plastic loading wave. When the element deletion method is used to simulate crack generation, adopting the maximum tensile stress failure criterion can accurately simulate the final distribution of cracks, but it is difficult to simulate the evolution process of cracks under cyclic impact loads.
查看更多>>摘要：The flow law of two-phase flow under complex capillary structure can be applied to explain the variability of development efficiency during the displacement, imbibition, and huff-and-puff process with different construction parameters. Microfluidic chips have attracted considerable attention as an effective laboratory research method on the displacement and imbibition processes in the complex pore-network. While, laboratory methods provide only an extremely limited amount of information, numerical simulation can reveal more detailed flow field information of two-phase flow in complex pore-network. In particular, computational dynamics methods can simulate the fluid flow process in the complex capillary structure. To this end, our study aimed to analyze the influence of different parameters on the oil recovery and swept area by relying on numerical simulations, dynamic analysis, and previous studies. Furthermore, by using distribution maps with flow filed and phase filed, we uniquely focused on the flow field information and dynamic process analysis during the displacement-imbibition process to elucidate the mechanism of remaining oil, trapped and displaced. Moreover, we examined the sensitivity characteristics of cumulative oil recovery during the displacement-imbibition process within a reasonably narrow parameter variation range. Lastly, some follow-up improvement suggestions were provided to facilitate the oil recovery under displacement-imbibition process.
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