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Journal of Petroleum Science & Engineering
Elsevier Science B.V.
Journal of Petroleum Science & Engineering

Elsevier Science B.V.

0920-4105

Journal of Petroleum Science & Engineering/Journal Journal of Petroleum Science & Engineering
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    Porosity prediction from pre-stack seismic data via committee machine with optimized parameters

    Gholami, AminAmirpour, MasoudAnsari, Hamid RezaSeyedali, Seyed Mohsen...
    14页
    查看更多>>摘要:Prediction of porosity from the seismic data via geophysical methods when limited number of wells are available is a challenging task that has high uncertainties. This study aims to construct a hybrid data-driven predictive model to establish a quantitative correlation between seismic pre-stack (SPS) data and the porosity. First, three intelligent models that are optimized by bat-inspired algorithm (BA): optimized neural network (ONN), optimized fuzzy inference system (OFIS), and optimized support vector regression (OSVR) are constructed for relating porosity to the SPS data. Then, to benefit from all individual optimized models, a final hybrid model was built via committee machine (CM) where single models are combined with a proper weight to predict porosity in the reservoir space. This approach is examined on the SPS data from an oil field in the Persian Gulf with a single exploratory well where input parameters (Vp, Vs, and rho) to the AI models are derived from a two-parameter inversion method. We found that the coefficient of determination, root mean square error, average absolute relative error, and symmetric mean absolute percentage error for the CM are 0.923615, 0.015793, 0.132280, and 0.061310, respectively. Moreover, based on four statistical indexes that are calculated for each model, CM outperformed its individual elements followed by the OSRV. A comprehensive analysis of the results confirms that CM with the OM elements is a superior approach for computing porosity from the SPS in the well and then throughout the entire reservoir volume. This strategy can aid petroleum engineers to have a better forecast of porosity population in the reservoir static model immediately following the data that is obtained from the first exploratory well. Ultimately, successful implementation of this approach will promptly delineate sweet spots that can replace uncertain and complicated conventional geophysical methods.

    Reservoir rock typing and electrofacies characterization by integrating petrophysical properties and core data in the Bangestan reservoir of the Gachsaran oilfield, the Zagros basin, Iran

    Maldar, RaminRanjbar-Karami, RasoulBehdad, AliBagherzadeh, Samira...
    24页
    查看更多>>摘要:The super-giant Gachsaran oilfield is situated in the Dezful Embayment of the Zagros basin. The main goal of this study is to characterize the reservoir rock types by integrating the available geological and petrophysical studies in the Bangestan reservoir along with adopting a way to figure out the optimal number of electrofacies codes. At the first step, the types of porosity and geological microfacies were studied by using 163 thin sections from the core samples. The microscopic studies revealed that fractures and intraparticle interstices are the most common porosities types. Also, they resulted in the identification of 4 microfacies in the Bangestan reservoir. In a complementary study, the Velocity-Deviation Log (VDL) was employed to determine the dominant pore types. By comparison of the VDL values and thin section studies' results, it was deduced that high micro-porosities along with hairline fractures are the predominant pore types of the Bangestan reservoir. At the second step, the optimal number of reservoir rock types (RRT) was determined by using the concept of hydraulic flow units. Thus, six flow units were distinguished by utilizing the Flow Zone Indicator (FZI) method in which the reservoir properties were improved from RRT-1 toward RRT-6. In the third step, the data clustering analysis, known as the electrofacies analysis, was employed to identify the accurate petrophysical rock types based on the meaningful segregation of capillary pressure curves within each electrofacies code and then propagated in non-cored intervals and boreholes. In this research, an optimal number of 7 electrofacies were identified by employing the petrophysical curves including effective porosity (PHIE), bulk density (RHOB), sonic (DT), and water saturation (SWE), along with considering the number of reservoir rock types and the defined geological microfacies, as well as the relations of the available capillary pressure data within different electrofacies codes. The validity of the proposed electrofacies was scrutinized through petrophysical results including shale volume, water saturation, and effective porosity. In the end, the electrofacies codes were compared to the defined geological microfacies. Finally, this study shows that the correlation of capillary pressure data and electrofacies codes can be resulted in figuring out the optimal number of electrofacies codes. In addition, by trying to honor the link between geological microfacies, capillary pressure, and petrophysical curves, the constructed electrofacies model, as a suitable practical integrated rock typing method, can be the foundation of property modeling, guide the spatial distribution of reservoir properties in the 3D model, aids to model the dynamics of fluid flow more realistically in reservoir simulation phase, and ultimately be beneficial for further development and production decisions in the Bangestan reservoir of the Gachsaran oilfield.

    A distributed surrogate system assisted differential evolutionary algorithm for computationally expensive history matching problems

    Ma, XiaopengZhang, KaiZhang, LimingWang, Yanzhong...
    15页
    查看更多>>摘要:Recently, surrogate assisted evolutionary algorithms (SAEAs) are widely studied and applied for history matching problems due to surrogate models can accelerate convergence. However, most of the SAEAs lose the ability of parallel sampling due to the introduction of surrogate models, in which, a small number of potential solutions are selected for evaluation in each iteration. Generally, history matching involves a large number of numerical simulations, and the role of parallel computing cannot be ignored. To address this issue, this paper proposes a distributed surrogate system assisted differential evolution algorithm, termed DSS-DE. A distributed surrogate system (DSS) based on ensemble learning techniques is first developed, which builds a large number of basic learners before optimization, to effectively approximate different regions in the search space. Following that, performing multiple differential evolution (DE) optimizers with different mutation operators concurrently to sample a set of solutions to find as many as possible local or global optima of the data mismatch objective function. Moreover, based on the DSS prediction, a parallel infill strategy is designed to screen the potential promising solutions. Combined with the convolutional variational autoencoder (CVAE) based parameterization technique, a history matching workflow is developed. Empirical studies on two multimodal benchmark functions demonstrate that the proposed algorithm can obtain high-quality solutions on a limited computational budget. Furthermore, the proposed history matching workflow is validated on three synthetic waterflooding reservoir case studies with different geological characteristics. The test results show that the effectiveness of the proposed algorithm for history matching problems.

    Rheological investigation of polymer/clay dispersions as potential drilling fluids

    Morariu, SimonaTeodorescu, MirelaBercea, Maria
    9页
    查看更多>>摘要:The rheological properties of poly(ethylene glycol)(PEG)/Laponite (R) RD (Lap) and poly(pmpylene glycol)(PPG)/ Lap aqueous dispersions, with 2% polymer and different clay concentrations, were investigated at 25 degrees C in order to establish the optimal composition to formulate a system applicable as drilling fluid. Some of the most important parameters, such as low shear rate viscosity, plastic viscosity, yield stress and flow behavior index, were determined and discussed. The PEG/Lap and PPG/Lap dispersions containing more than 2.55% and 3.10% clay, respectively, could be considered in the formulation of drilling fluids. The yield point value of dispersions, which is suitable for drilling fluid applications, increased while their plastic viscosity decreased in the presence of NaCl. By addition of NaCl, the complex viscosity of these samples becomes independent of temperature in the range 10 degrees C - 65 degrees C. Zeta potential value decreases as the Lap concentration increases up to about 3% clay and, higher clay content no longer affects it.

    A technical turning point-based framework to optimize CO2 EOR-storage: Capacity dynamics of Brownfield Residual Oil Zones

    Liu, JiachenEttehadtavakkol, Amin
    17页
    查看更多>>摘要:Residual Oil Zones (ROZs) contains considerable oil at residual saturation underlying Main Pay Zones (MPZs), which renders its development challenging in conventional manner. Enhanced oil recovery (EOR), for example, CO2 injection is therefore introduced. This technique unleashes the potentials of ROZs in terms of EOR and carbon storage. In field-scale simulation regard, although some researchers have investigated the effects of several operational variables such as well pattern, perforation interval, injection mode and injection strategy, on CO2 EOR-storage performances, no published work attempts to reveal the EOR-storage capacity dynamics/variations of Brownfield ROZ reservoir upon its development. By addressing the questions: (1) when to start considering ROZ expansion beyond MPZ; (2) the timing when to perform ROZ expansion that could maximize the profit; (3) whether ROZ expansion always benefits the project; (4) what development strategy is more favorable given a certain CO2 availability, this paper reveals the incentives of when to include ROZ into CO2 EOR-storage project beyond MPZ in development strategy regard. Based on the envisioned technical turning point where ROZ outperforms MPZ assuming propensity to oil production, novel performance metrics-ROZ oil production critical point (ROZ-OPCP) and ROZ opportune oil production trade-off point (ROZ-OOPTP), are brought up to technically optimize the development strategy design of Brownfield ROZ reservoir, upon which a resultant designing framework is established. The concepts and framework are envisioned to facilitate development strategy configurations, narrow down the target range for optimization, reduce the cost of trial-and-error and therefore promote the Carbon Capture and Storage (CCS). Simulation study also provides following insights on CO2 EOR-storage in Brownfield ROZ reservoir: (1) above ROZ-OPCP, the development of ROZ beyond MPZ is technically feasible under moderate and sufficient CO2 supply case since positive surpluses in EOR-storage are observed. Project could benefit most from sequential and simultaneous MPZ-ROZ development under moderate and sufficient CO2 supply case, respectively; (2) ROZ expansion without considerable CO2 availability and opportune timing could technically and economically impair the project, and ROZ-OOPTP needs to be considered herein; (3) Designing CO2 injection scenarios requires compromises. e.g., Higher injection rate in ROZ increases CO2 storage and brings forward the peak EOR-storage performance, while the lower injection rate prolongs the desirable EOR-storage performance; (4) The envisioned technical turning point and the CO2 EOR-storage capacity dynamics may strongly depend on original quality of ROZ and the current usage of MPZ, and less usage would lead to later occurrence of technical turning point.

    Crude oil emulsion breaking: An investigation about gravitational and rheological stability under demulsifiers action

    Bahu, Juliana OtaviaMiranda, Nahieh ToscanoKhouri, Nadia GagliardiBatistella, Cesar Benedito...
    13页
    查看更多>>摘要:Emulsions are common in the oil industry, being present in the extraction and production stages. Its formation occurs with the contact of brine and crude oil under intense flow. The presence of emulsified water (dispersed droplet size, phi <= 50 mu m) in crude oil can negatively impact its exploration, transportation, and refining, making transportation more expensive, requiring more energy for heating, and causing equipment corrosion on all processes. In addition, crude oil has salts and sediments that encrust and corrode equipment of the primary oil treatment unit and distillation towers, also causing catalyst poisoning in the cracking step. Therefore, such components need to be removed for subsequent refining processes. To prevent these problems, the dehydration/ desalting of crude oils is a strategy adopted to reach adequate values of water, salts, and sediments required in the refineries for the next steps after primary treatment. However, the emulsion breaking is influenced by several factors that affect the stability of crude oil (W/O emulsion), such as viscosity, contents of water, salts, sediments, and natural surfactants, among others. Given this perspective, this work investigated the stability of two different types of crude oils with demulsifier under the action of gravity (bottle test) and shear stress (rheology). The comparisons of gravitational and rheological techniques concluded that the shear stress sweep analyses are useful to evaluate the demulsifier performance in the emulsion breaking, being a reliable and fast methodology. Such studies allowed the identification of adequate parameters: temperature (80 degrees C) and, demulsifier type and quantity (500 ppm) for efficient crude oil phase separation, without using washing water. The physicochemical and rheological characterizations clarified the crude oil's colloidal stability behavior to understand the impurities' influence on the oils' properties (crude and desalted).

    Multiphase transient analysis of horizontal wells during CO2-EOR

    Li, LonglongWu, MingluLiu, YuewuDing, Jiuge...
    9页
    查看更多>>摘要:We apply a numerical well test model that considers the transient flow in well and the complex displacement mechanisms for the multiphase transient analysis of horizontal wells during CO2-EOR. Aimed to perform a systematic and reliable analysis, we run the model on a high-resolution non-uniform grid to accurately capture the transient flow in the near wellbore region as well as the complex displacement process. In this work, we interpret the pressure response curve in two steps to find the root causes of the particular transient behaviors. First, we identify five typical flow regimes through the traditional pressure transient analysis method for horizontal wells which gives us a basic understanding of the characteristics of the pressure response curve. Second, assisted with the corresponding analysis method, we figure out the durations on the curve that correspond to different component banks. By taking the complex displacement mechanisms into consideration, we find that the component banks have a large influence on the curve and identify the root cause of each unique characteristic. Besides, we conduct a systematic sensitivity analysis with respect to multiple parameters such as miscible condition, wellbore storage coefficient, skin factor, horizontal well length, anisotropy, and amount of injected CO2. Finally, we have a better understanding of the transient pressure behavior of horizontal wells during CO2-EOR, find a way to determine the miscibility underground, and feel more confident in applying the pressure transient data for analysis and parameter estimation.

    Developing novel bio-nano catalyst well clean up fluid to remove formation damage induced by polymeric water-based drilling fluids

    Mohammadi, Mojtaba KalhorRiahi, SiavashBoek, Edo S.
    10页
    查看更多>>摘要:Drilling and completion fluids may cause significant formation damage in oil and gas reservoirs, directly affecting productivity. For many years, operators have applied different stimulation practices such as acidizing, oxidizers, chelating agents, and enzyme treatment to remove formation damage associated with drilling fluids filter cake. An enzyme-based biological treatment was combined with other chemicals or additives as a selective well clean-up practice to improve removing polymer content in the filter cake. However, the secondary formation damage such as deep cleaning of the invaded zone and wettability alteration remained the main concern. This paper presents the development of an innovative clean-up fluid formulation by immobilizing an enzyme and a selective nanoparticle as Bio-Nano Well Clean-Up Fluid (BNWC) in potassium chloride brine to enhance WBM filter cake removal. Several bulk experiments, including; precipitation, iodine test, and viscosity measurement, demonstrate the enzyme's optimization, the nanoparticle concentration, and base fluid brine. BNWC in potassium chloride brine showed the highest HPHT filtration rate at 200 degrees F and differential pressure of 100 psi and increased the filtration rate by more than 90 percent compared to the conventional enzyme in the same brine. Contact angle measurements confirmed wettability alteration of the carbonate rock to water-wet, and IFT measurements showed higher oil mobility potential. Finally, core flooding tests at reservoir conditions showed a 300 percent enhancement in injection rate and a 50% improvement in core permeability after damage. The immobilization of the enzyme with the nanoparticle has been developed successfully for other applications in bioremediation, farming, and other industries, but the novelty of this research demonstrates the application of nanobiocatalysts in drilling fluids for the first time. This innovative clean-up fluid enhances the enzymatic activity and removes primary and secondary formation damage associated with drilling fluid filter cake.

    Pore-scale characterization of CO2 front progress through a porous medium using a free energy model based on Phase-Field Lattice Boltzmann Method

    Moradi, BijanMoghadam, Amir HosseiniRasaei, Mohammad RezaPapi, Ali...
    13页
    查看更多>>摘要:Pore-scale simulation of CO2 front progression through a porous medium has been investigated by a free energy model based on phase-field lattice Boltzmann method. Visualization of the fluids distribution in the breakthrough time reveals a strong dependence of front pattern on viscous and capillary forces interaction. Therefore, the dominance of each force imposes a different front pattern on the system. According to the percolation theory, increasing the capillary number reduces the invading fluid saturation and, consequently, the sweep efficiency, because the viscous fingering regime will intensify. However, a uniform pattern is observed when the mobility ratio is high, whereas the front evolution is facilitated in the opposite case. Impressive results have also been obtained regarding the wetting conditions. Since an upward trend in the displacement efficiency from strong drainage to strong imbibition processes is expected, this trend has changed due to the capillary suction effects in the strong imbibition process. According to experimental studies, the viscous fingering phenomenon will be proportional to the capillary suction. Furthermore, new areas have also been introduced to predict the displacement regimes.

    Water sorption and transport in Silurian shales

    Svabova, MartinaVorokhta, Maryna
    8页
    查看更多>>摘要:We have studied the transport of water in shales through gravimetric water vapour sorption experiments. Kinetic data have been evaluated and several kinetic models have been compared, with emphasis on time-dependent diffusivity models. The effective diffusivities as a function of relative pressure show an initial increase corresponding to the sorption to primary adsorption centres, followed by water cluster formation. The final decrease in effective diffusivity is connected with flattening of the pore-mouth meniscus. Introducing the flow rate kinetic parameter enables samples with different amounts of adsorbed water to be compared, showing that the highest value of the flow rate kinetic parameter is connected with the sample with largest surface area and the greatest micropore volume.