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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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    Digital rock physics: Defining the reservoir properties on drill cuttings

    Kadyrov, RailNurgaliev, DanisSaenger, Erik H.Balcewicz, Martin...
    21页
    查看更多>>摘要：Well drilling with core extraction is one of the most expensive procedures in the oil industry. The potential alternative, which may open opportunities for cost-efficient acquisition of petrophysical data, can be an approach based on digital analysis of drill cuttings. The main purpose of this research was to evaluate the possibility of using digital cuttings analysis and rock physics for reservoir properties evaluation. The carbonate samples of core and cuttings were simultaneously collected from the same intervals during the drilling of deviated wells in the Carboniferous reservoir of the oil deposit in the Republic of Tatarstan, Russia. Based on the core analysis using the optical study of thin sections and XRD, we investigated sedimentological and mineralogical features and classified all lithotypes of well intervals. The standard samples were produced from all defined facies and their reservoir properties were studied in routine tests. The largest cuttings from each well interval were separated and their structures were compared using mu CT with core subsamples of the same intervals. We assessed the changes of cuttings structure occurring in the drilling process, which include the colmatation of the pore space with drilling fluid and disintegrated rock particles and the formation of secondary fractures. Detailed analysis of cuttings from one well interval consisting of the border between the facies of high porous grainstones with packstones and dense micrite limestones demonstrated that high porous varieties were eroded in the drilling process. The analysis of chemical composition using XRF-mapping, XRD and SEM with EDS showed that most of the cuttings were constituted by disintegrated rock particles or form elements (e.g. separate fusulinids) cemented by drilling mud. However, more durable cuttings from dense micrite limestones facies were generally retained their dominant calcite composition and original rock structure, with only secondary fractures. Finally, we analyzed pore space properties and performed digital simulations of wave propagation velocities to compare the characteristics of these cuttings and core subsamples from this lithotype, scanned in the same mu CT settings. The results demonstrate close characteristics of porosity 0.08-0.6%, dominant pore sizes 1-60 mu m and velocities Vp = 6130-6240 m/s, Vs = 3180-3230 m/s. However, the comparison of obtained values with measured on standard samples shows a significant difference, which is caused by deviation from REV. The potential use of cuttings for assessing reservoir and petrophysical properties can be possible in case of provision with the factors of cuttings structure alteration, representativity of samples, as well as optimization for these purposes of the drilling process with cuttings selection.
      原文链接:
    • NSTL
    • Elsevier

    A numerical and experimental investigation into the influence of CO2 on the stability of W/O emulsion

    Li, Yi-BoDeng, Qing-HuanHuang, TaoZhang, Ya-Qian...
    9页
    查看更多>>摘要：The formation of water in oil (W/O) emulsion can result in flow issues in the reservoir and a high cost of demulsification throughout the water treatment process. Without treatment, the W/O emulsion takes a long time to settle, which results in blockage in porous media. CO2 has strong interaction with crude oil and so has the potential to alter the settling process of W/O emulsion. The purpose of this paper is to undertake a numerical and experimental investigation into the influence of CO2 on the emulsion stability. To anticipate the settling process of a W/O emulsion in a high-pressure environment, a mathematical model was created that included a CO2 diffusion model, a viscosity prediction model, and an emulsion settling model. A high-pressure reactor was used to model the emulsion demulsification process at three different pressure conditions and to evaluate the model's prediction capability. The results indicate that under a high-pressure CO2 atmosphere, the demulsification process of a W/O emulsion can be accelerated. The CO2 dissolution and diffusion into the oil phase might enhance the likelihood of droplets colliding, resulting in the demulsification of the W/O emulsion system. Pressure has a significant influence on the stability of the emulsion. High pressure accelerates the CO2 dissolution process and significantly reduces the time required for the emulsion system to reach equilibrium. Additionally, the oil/water ratio can affect the stability of a W/O emulsion. At the same pressure, an emulsion with a higher oil/water ratio required a shorter time to reach equilibrium and had a higher equilibrium viscosity.
      原文链接:
    • NSTL
    • Elsevier

    A critical analysis of power conditions in sucker-rod pumping systems

    Takacs, Gabor
    10页
    查看更多>>摘要：The most decisive constituent of operating expenditures in sucker-rod pumping operations is related to the system's electric power use as most installations are driven by electric motors. Consequently, the reduction of operating costs can be translated to the reduction of energy losses both downhole and on the surface. Therefore, the energy efficiency of the surface and downhole components of the pumping system as well as the overall system efficiency play a big role in maximizing profits. The paper presents a critical analysis of the energy efficiency of the individual components of the sucker-rod pumping system and introduces novel models to find the system's total efficiency. The typical energy losses in the sucker-rod pumping system's main components (the downhole pump, the sucker-rod string, the surface pumping unit, the gearbox, the V-belt drive, and the prime mover) are discussed in detail. It is demonstrated that the level of the pumping unit's counterbalancing as well as any inertial effects do not impact on the net gearbox torques and on the required average mechanical output power of the motor. The energy consumption of the electric motor, however, is affected by the pumping unit's counterbalancing and the inertial effects because of the changes in motor efficiency due its variable loading within the pumping cycle. The system's useful output power is performed by the downhole pump when it lifts the produced liquid to the surface. The paper demonstrates that the so-called hydraulic power, calculated from the increase of the produced liquid's potential energy, is a reliable indicator of the system's useful power. Using the hydraulic power together with the electric power taken from the power supply permits an easy way to assess the over-all energy efficiency of the pumping system. The paper proposes several other variants of system efficiency calculations; they are based on the fact that all components of the pumping system are connected in series to each other. Sizing of electric motors for sucker-rod pumping installations is normally done with the use of a cyclic load factor (CLF) that accounts for the fluctuations in motor load during the pumping cycle. Originally, CLFs were found from the variation of motor current, but mechanical CLFs based on net gearbox torques are much more practical to use. This practice is fully justified in the paper by proving that the correlation between the motor's real current and its net torque loading is nearly linear. It is further shown that the safety of sucker-rod pumping installation design is improved if the electric motor is sized with the use of a mechanical CLF because that case gives the highest required nameplate motor power.
      原文链接:
    • NSTL
    • Elsevier

    Neural Network based Mechanical Earth Modelling (MEM): A case study in Hassi Messaoud Field, Algeria

    Aoun, Ala EddineSoto, RicardoRabiei, MinouRasouli, Vamegh...
    19页
    查看更多>>摘要：Accurate estimation of in-situ stresses is of great importance in the oil and gas industry from the exploration to the field development and production phases. The collected logs and mini-frac data in the last 15 years in the Hassi Messaoud Field (HMD), Algeria, shows that the reported state of stresses in this field is not consistent. This called for further studies to estimate more accurately the state of stresses, which more specifically will be used for the design of hydraulic fracturing at a later stage. This paper presents the results of the Mechanical Earth Model (MEM) constructed for the HMD field in Algeria. The results of the MEM, which is continuous logs of formations' elastic and strength properties, as well as the state of the in-situ stresses will be the direct input to the hydraulic fracture (HF) design. Hydraulic fracturing is the prime technique used in the field in order to enhance recovery from this tight sandstone reservoir. MEM is built beyond the conventional correlation with both a Generalized Linear Model (GLM), which serves as a simplified "ground truth" and three Artificial Neural Networks (ANN) layers: the first one is training mechanical properties from lab data, the second one trains shear and compressional sonic waves from acquired log data and the last one uses mini-frac data to calculate and train stress regimes from a poro-elastic model. The model is calibrated with the observed breakouts and fracturing data and a close agreement is observed. The work presented in this paper elaborates a detailed roadmap to accurately approximate and synthesize missing data using ANN's and extend it across the rest of the field to build, a 3D MEM. It is hoped that the results of this study can improve the HF operations in the field, which is currently reported to be not efficient.
      原文链接:
    • NSTL
    • Elsevier

    Mechanistic modeling of hybrid low salinity polymer flooding: Role of geochemistry

    Al-Shalabi, Emad W.Alameri, WaleedHassan, Anas M.
    14页
    查看更多>>摘要：Low salinity polymer (LSP) based enhanced oil recovery (EOR) technique is getting more attention due to its potential of improving both displacement and sweep efficiencies. Modeling LSP flooding is challenging due to the complicated physical processes and the sensitivity of polymers to brine salinity. In this study, a coupled numerical model has been implemented to allow investigating the polymer-brine-rock geochemical interactions associated with LSP flooding along with the flow dynamics. MATLAB Reservoir Simulation Toolbox (MRST) was coupled with the geochemical software IPhreeqc, which is the interface module of Phreeqc (i.e., pH-Redox-Equilibrium in C programming language). The effects of polymer were captured by considering Todd-Longstaff mixing model, inaccessible pore volume, permeability reduction, polymer adsorption as well as salinity and shear rate effects on polymer viscosity. Regarding geochemistry, the presence of polymer in the aqueous phase was considered by adding a new solution specie and related chemical reactions to Phreeqc database files. Thus, allowing for modeling the geochemical interactions related to the presence of polymer. Coupling the two simulators was successfully performed, verified, and validated through several case studies. The coupled MRST-IPhreeqc simulator allows for modeling a wide variety of geochemical reactions including aqueous, mineral precipitation/dissolution, and ion exchange reactions. Capturing these reactions allows for real time tracking of the aqueous phase salinity and its effect on polymer rheological properties. The coupled simulator was verified against Phreeqc for a realistic reactive transport scenario. Furthermore, the coupled simulator was validated through history matching a single-phase LSP coreflood from the literature. This paper provides an insight into the geochemical interactions between partially hydrolyzed polyacrylamide (HPAM) and aqueous solution chemistry (salinity and hardness), and their related effect on polymer viscosity. This work is also considered as a base for future two-phase polymer solution and oil interactions, and their related effect on oil recovery.
      原文链接:
    • NSTL
    • Elsevier

    Development of novel inhibitive water-based drilling muds for oil and gas field applications

    Aydin, Mustafa GoktanYalman, EmineFederer-Kovacs, GabriellaDepci, Tolga...
    19页
    查看更多>>摘要：The aim of this study is to develop inhibitive drilling fluid systems generated from waste materials that can contribute to the reduction of potential well instability problems caused by drilling fluid based on rheological and filtration properties. In this study, a comprehensive experimental work was carried out to assess suitability of fly ash and rice husk ash, which are quite a large amount of waste, in inhibitive water based-drilling fluids at ambient temperature. To this end, inhibitive drilling fluids systems were formulated with various concentrations (0, 1, 3, 5, 7, 9, 12.5, 15 (wt%)) of fly ash and rice husk ash with 0, 2, 4, 7, 9, 12.5, 15 (wt%) concentrations in the two type of inhibitive drilling fluid systems and combined use of fly ash and rice husk ash with their optimum concentrations determined was analyzed in the inhibitive drilling fluid in order to determine the drilling fluid with the most favorable characteristics based on rheological and filtration properties including apparent viscosity (AV), plastic viscosity (PV), yield point (YP), gel strength, fluid loss and mud cake thickness. In addition, grinding impact of fly ash particles in the inhibitive drilling fluid system was determined in the development of the drilling fluid by employing mechanically ground fly ash for 30, 60 and 120 min in a tumbling ball mill. Finally, fly ash and rice husk ash were characterized based on X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Experimental results show that developed drilling fluids with fly ash and rice husk ash not only enhanced rheological properties but also improved the filtration properties by increasing the rheological parameters and decreasing fluid loss and mud cake thickness. With the developed drilling fluids, AV, YP and PV increased by 35%, 32%, 28%, respectively with fly ash for the 12.5 wt% concentration while the parameters increased by 19%, 27%, 14%, respectively with the 4 wt% rice husk ash. Gel strengths of the fluids slightly increased compared to reference fluid and were in acceptable range. On the other hand, developed drilling fluid resulted in a 10% and 12% reduction in fluid loss for fly ash and rice husk ash at 12.5 wt% and 4 wt% concentrations, respectively, as well as a 54% and 63% reduction in mud cake thickness. In addition, the results reveal that developed drilling fluid with sieved fly ash yielded superior flow behavior compared to drilling fluid formulated with ground forms of fly ash. Consequently, based on the study, non-damaging and inhibitive drilling fluid systems were developed by using waste material fly ash and rice husk ash, and hence enhancing performance of drilling operation as well as reducing the risk of amount of wastes disposed to the environment and the potential of issues such as formation damage, wellbore instability caused by drilling fluid and associated challenges.
      原文链接:
    • NSTL
    • Elsevier

    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.
      原文链接:
    • NSTL
    • Elsevier

    Permian and Triassic hydrocarbon migration and accumulation in the Cainan area, Junggar Basin, China

    Song, JianyangChen, TaoZhang, Jinliang
    20页
    查看更多>>摘要：Gas Chromatography-Mass Spectrometer (GC-MS), chloroform asphalt "A", and carbon isotope measurements were used to determine hydrocarbon migration pathways. This study focused on hydrocarbon migration pathways and accumulation distribution in the Wucaiwan region, Junggar Basin, China. The biometric parameters were used to compare oil sources. Type and distribution characteristics of natural gas were determined in order to study the different strata. Quantitative grain fluorescence (QGF) and quantitative grain fluorescence on extract (QGF-E) were analyzed to determine the hydrocarbon migration and charging periods. Geochemical indexes, such as, n-alkane, triterpenoids, sterane, and hopane, were utilized to investigate the pathways of hydrocarbon migration. Recent studies on petroleum maturity have focused on comparison of source rocks and reported that the maturity effects of source rock and reservoir oil are weak, while those effects are high in the Liuchu area. Analysis of triterpenoid and steroid hydrocarbon biomarkers elucidate the underground petroleum migration pathways to the reservoirs. Geochemical analyses of hopane and cholestanes were used. The alpha alpha alpha C29 (20 S)/(20 S + 20 R), C29 beta beta/(alpha alpha + beta beta), and C31 hopane 22R/C30 hoopane ratios, and C19/C21 tricyclic terpane ratio, C19/C21 tricyclic terpenes, C31 (22 S)/(22 S + 22 R), and C29 (20 S)/(20 S + 20 R) ratios were analyzed to determine the maturity of crude oil. Petroleum migrated along fault, sandbody, and unconformity, which suggest vertical and lateral migration occurred. Reservoir sandstone porosity and mudstone content of the thick caprock are likely to limit lateral hydrocarbon migration. Petroleum migration and accumulation primarily occurred by vertical migration and lateral migration was weak. The study offers an improved understanding of uncertain hydrocarbon migration pathways and further developed the hydrocarbon migration and accumulation models.
      原文链接:
    • NSTL
    • Elsevier

    Accurate, cost-effective strategy for lean gas condensate sampling, characterization, and phase equilibria study

    Zahedizadeh, ParvizOsfouri, ShahriarAzin, Reza
    22页
    查看更多>>摘要：Accurate recognition of the fluid phase behaviour is the most important and first step for the preservation and hydrocarbon reservoir management. Among the various hydrocarbon fluids, the lean gas condensate fluids show complex and unique behaviour. Due to the nature of these fluids, errors in the laboratory constant volume depletion (CVD) experimental data are inevitable. In this study, the significance of using CVD data in the EoS tuning process is debated using six samples of lean gas condensate. According to the negative composition in the CVD data material balance of all samples, just data of the constant composition expansion (CCE) experiment, saturation pressure, and liquid density in the stock tank are used for tuning the equation of state (EoS) as fundamental experimental data. The results of this study demonstrate that without using any CVD experimental data in the EoS tuning process, this data can be generated accurately using tuned EoS with fundamental data. Therefore, there is no need to do CVD experiments for lean gas condensate fluids characterization, which leads to reduces not only the error in the simulation process but also the laboratory costs. Furthermore, the tuning strategy in this study demonstrates that molecular weight of plus fraction and the volume shift parameter of the heaviest pseudo-component are the effective parameters to adjust the EoS. The objective function has reduced from 0.7360 to 0.1538 (79.10% improvement) just by using these two parameters. A constrained tuning strategy was proposed to keep the critical properties and acentric factor expected trends versus carbon number. The results show uniform and swing trends in the case of constrained and unconstrained tuning strategies, respectively. Therefore, using a constrained tuning strategy is essential to obtain a fluid with an authentic thermodynamic background after the tuning process. The proposed analysis method of CVD experimental data suggests that gas compressibility factor and gas composition as the main sources of error, while the experimental parameters of retrograde liquid and cumulative gas production have ignorable errors.
      原文链接:
    • NSTL
    • Elsevier

    Reduction of formation damage in horizontal wellbores by application of nano-enhanced drilling fluids: Experimental and modeling study

    Shojaei, NimaGhazanfari, Mohammad Hossein
    17页
    查看更多>>摘要：One of the basic challenges during drilling horizontal wellbores is the damage induced by invasion of mud filtrate into the formation. Addition of nanoparticles to drilling fluids has been recognized as a measure of control and reduction of filtrate invasion, which is the primary mechanism of the aforementioned formation damage. Despite notable advances in composing Nano-enhanced drilling fluids, the role of nanoparticle hydrophobicity on performance of the fluids has not been well studied. This study is based on a combined experimental-numerical methodology. In the experimental section, a procedure to find the optimum composition of Nano-enhanced water-based samples, containing nanoparticles of hydrophilic/hydrophobic silica and lipophilic clay to minimize the formation damage associated with mud circulation is recommended. The main idea was to investigate the effect of hydrophobicity of nanoparticles on damage reduction and furthermore, discover how other properties such as types/concentration of nanoparticles/ micro-sized additives, temperature and pressure would affect functionality and characteristics of drilling fluids. In order to more accurately and practically investigate any probable enhancements in performance of fluid samples a particular radial filtration setup was designed and used; then, functionality of mud samples was examined on grain packed porous media at radial flooding flow condition. Results revealed that samples containing 0.2 wt. % hydrophobic nanosilica had the best functionality with returned permeability of 68.4% and 51.1% for the cases of water saturated and oil saturated porous media, respectively. In the modeling section, mass balance and momentum equations were solved simultaneously by using elapsed time data. Permeability as well as thickness of mud cake formed on the wellbore wall were evaluated and compared for different Nano enhanced mud samples. Results showed that nano-enhanced drilling fluid samples generated thinner mud cakes with lower permeability values during quite shorter period of time. Results of this work might be helpful to better understand the behavior of nano-enhanced drilling fluids in radial porous systems at different conditions of nanoparticles hydrophobicity and applicable to minimize the induced formation damage during drilling of the horizontal section of a production well.
      原文链接:
    • NSTL
    • Elsevier