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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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    Mechanisms for the anisotropic enrichment of organic matter in saline lake basin: A case study of the Early Eocene Dongpu Depression, eastern China

    Jiang, FujieChen, DiZhu, ChenxiNing, Kangchao...
    15页
    查看更多>>摘要：Organic-rich terrestrial shales, the most promising shale oil production layer, are widely distributed in major basins in China, and they are usually interbedded salt rocks. Understanding the role of salt rocks in the organic matter (OM) enrichment in shale sediments has important enlightenment for shale oil exploration. The shale of the third member of the Eocene Shahejie Formation (Es-3 shales) in the Dongpu depression of the Bohai Bay Basin is dominated by clay minerals, with a non-negligible proportion of gypsum, anhydrite, and halite. They contain abundant OM with a mean total organic carbon content of 1.26 wt %. The development of salt rocks revealed the arid and transiently humid climate during the Es-3 period and an evaporating environment with a shallow lake level at the Dongpu Ancient Lake Basin. OM enrichment was synthetically affected by the palaeoenvironment during the Es-3 period. The paleolake with a paleosalinity as high as 23.43 parts per thousand was nutritious and promoted the prosperity of salt loving organisms causing high paleoproductivity. The Es-3 shales were deposited under anoxic and dysoxic conditions in a deep lake, which provided good conditions for OM preservation. In addition, salt rocks itself are good caprocks to prevent the loss of shale oil. Under the dual guarantee of high productivity and good preservation conditions, OM is much enriched in the Es-3 shales. OM enrichment was synthetically affected by the palaeoenvironment during the Es-3 period. The horizontal difference of paleoclimate controlled the discrepancy of salinastones distribution, OM enrichment, paleosalinity, andpaleoproductivity in different saline surroundings of Dongpu Depression. The composite patterns of palaeoenvironmental variation affected the vertical anisotropic enrichment of OM. Seven stages were divided for the Es-3 period to reflect the effects of vertical anisotropy on OM enrichment. Stages I, V, and, VII deposited thick salt under an arid climate and provided a good seal-capping and preservation condition for the OM enriched in stages II, III, IV, and VI. The shale reservoirs deposited in stages III and IV were favorable for shale oil exploration.
      原文链接:
    • NSTL
    • Elsevier

    Performance of thermophilic strain on the reduction of viscosity of crude oil under high pressure and high temperature conditions: Experiments and modeling

    Sakthipriya, N.Doble, MukeshSangwai, Jitendra S.
    12页
    查看更多>>摘要：The matured reservoirs all over the world leads on the way to highly viscous crude oil. The heavy and waxy oil would act as an alternative to conventional reserves, only with the application of a technology to reduce the viscosity. This study aims to analyze the microbial activity on crude oil, and the synergetic effect of microbial interaction, pressure and temperature on viscosity. The reports on application of microorganisms on the viscosity reduction of crude oil are very rare at high temperature and high pressure environment. The application of Bacillus subtilis, a thermophilic bacterium for improving the flow properties of waxy crude oil is investigated at various temperatures and pressures in a high pressure cell. This study has been carried out to simulate the microbiological phenomenon occurring in the reservoir, when a bacteria is introduced for viscosity reduction. Bacillus subtilis could grow well from 0.1 to 5 MPa, and less growth was observed at 10 MPa. The maximum 52.1% of viscosity of crude oil was reduced at the pressure of 1 MPa, temperature of 50 degrees C, and at the shear rate of 1000 s-1 by microbial interaction. The implicit correlations as a function of pressure, temperature, and shear rate has been developed to predict the viscosity of crude oil during the microbial treatment. This work also proposed a new model incorporating the thermodynamic and microbial kinetics to estimate the viscosity of crude oil during the process of microbial degradation. The proposed model has provided satisfactory predictions when compared with the experimental values of degradation. All these findings demonstrate the influence and suitability of Bacillus subtilis in crude oil production and transportation.
      原文链接:
    • NSTL
    • Elsevier

    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).
      原文链接:
    • NSTL
    • Elsevier

    Numerical study of the mud loss in naturally fractured oil layers with two-phase flow model

    Li, LeiYang, JinSong, YuYan, De...
    9页
    查看更多>>摘要：Drilling in the naturally fractured formations always encounters severe mud loss, which endangers the drilling safety. In oil & gas layers, a larger quantity of mud loss has great adverse effects on later oil and gas production. Therefore, it makes the knowledge of mud loss very important, and after that, it is instructive to control the mud loss in the oil layer. In this paper, we first consider the mud loss process using a two-phase flow model. A discrete fracture network model is employed to describe the fluid transfer between fractures and matrix pores. And different relative permeability curves and capillary pressure functions are used in matrix pores and natural fractures. The finite element method and "upwind" scheme are employed to deduce the numerical discretized formulas. The correctness of our model is verified with the published literature. Then a sensitivity analysis is performed to study the laws of mud loss in naturally fractured oil-wet formation. Compared with single-phase flow models, the mud loss rate of two-phase flow model is lower. The two-phase flow model is used to identify the most influential factors on mud loss and predict the distribution of water saturation in oil formation during the drilling process. We find that: since the pressure increase zone is much larger than the water saturation increase zone, the size of the water invasion zone is unknown in the single-phase flow model. The most important influential factors of mud loss in the oil layer are fracture connection, drilling fluid density and matrix permeability. Once the natural fractures are connected to the wellbore, the mud loss rate is much higher than that when the natural fractures are not connected to the wellbore. The capillary pressure has little effect on the mud loss. The larger the capillary pressure, and the lower the mud loss rate. The model in this paper is instructive to learn the law of mud loss and contamination range of drilling fluids in oil layers.
      原文链接:
    • NSTL
    • Elsevier

    Effect of compaction and imbibition on benefits of drawdown management in shale oil production: Uncertainty in recovery driving mechanisms

    Wijaya, NurSheng, James
    21页
    查看更多>>摘要：Economic production from shale oil reservoirs relies on the longevity of conductive fractures. Choke or draw-down management is believed to better preserve the fracture conductivity during the early life of the wells, which thus potentially leads to higher ultimate oil recovery. However, there is no strong consensus among the previous literature as to whether choke management can offer incremental oil recovery in the long term. Even if it can, the mechanism is not well understood, and the economic benefit can be challenged, because the choke management slows down the early oil production, which is worth the most in terms of Net Present Value (NPV). In this study, a series of coupled flow-geomechanical numerical simulations is performed to examine the effect of choke management on the ultimate oil recovery and NPV. We built multiple reservoir realization models, each of which is validated based on the same field production data from Middle Bakken shale-oil reservoirs to perform probabilistic production forecasts. The different reservoir realization models are built to assess the uncertainty in the Stimulated Reservoir Volume parameters, including natural fracture spacing, water saturation in the matrix and fracture, and formation compressibility. The different reservoir parameters lead to each model having different primary recovery driving mechanisms of oil recovery, including imbibition and compaction drive. This study quantitatively demonstrates that the choke management seems to increase both the ultimate oil recovery and NPV if the oil recovery is strongly driven by imbibition. A mechanistic discussion for this claim is presented.
      原文链接:
    • NSTL
    • Elsevier

    Development of in-situ starch grafted copolymerized gels for conglomerate reservoir conformance control and oil recovery improvement

    Luo, QiangTang, KeBai, LeiLi, Kai...
    11页
    查看更多>>摘要：To improve the waterflooding efficiency in the conglomerate reservoir with severe heterogeneity in the Xinjiang Oilfield, an in-situ starch grafted copolymerized gel (ISGCG) system as a strong plugging material was developed. Through viscosity experiment, rheological measurement, gel strength test, and sand pack plugging experiment, the gelation performance of the ISGCG system were systematically evaluated in the laboratory. Experimental results showed that the ISGCG system was a typical pseudoplastic fluid. It was also a shear-thinning fluid, which is beneficial to its pumping and deep propagation in the petroleum formation. In addition, with the increase of starch concentration, both the elastic modulus (G') and viscous modulus (G '') of the gel system increased first and then decreased. When the concentration of starch reached 3 wt%, the viscoelasticity was the strongest. In addition, as the concentration of cross-linking agents increased, the gel strength also increased first and then decreased. However, the gelation time slightly changed. Moreover, with the increase of initiator concentration, the gelation time gradually reduced, but the gel strength did not change significantly. The ISGCG system had excellent injection performance in the conglomerate reservoir rocks since its viscosity was low. It also had a strong adhesion force with the reservoir sand after cross-linking, so the robust plugging strength during the secondary waterflooding process can be guaranteed. Last, the in-situ starch grafted copolymerized gel (ISGCG) has been successfully applied in a conglomerate reservoir in the Xinjiang Oilfield, China. After treatments of the ISGCG system, the daily water cut of the treated well reduced from 92.7% to a minimum of 75.8%, and the daily oil production increased from 8.1 to 18.8 t/d. It shows the ISGCG system is a promising material for conformance control and oil recovery improvement in conglomerate reservoirs.
      原文链接:
    • NSTL
    • Elsevier

    A well rate prediction method based on LSTM algorithm considering manual operations

    Li, XianglingLi, XianbingYu, ChunyeFan, Dongyan...
    9页
    查看更多>>摘要：Manual operations such as changing the size of chokes as well as opening and closing of the well have a great impact on oil and gas production from the well. This scenario is not considered in most deep learning methods for predicting productivity. Therefore, a deep learning method based on a long short-term memory (LSTM) neural network model was established to predict well performance considering the manual operations. The input dataset was composed of data related to choke size, daily opening time series, and production; the first 90% of the dataset was used as the training set and the remaining 10% was used as the test set. The deep learning model was constructed using a LSTM module, regularization process, and dropout network. The formulated LSTM model was proficient compared with a model that did not consider the manual operation process, and showed better prediction accuracy. Through multiple experiments, the production-related time step was optimized at three, indicating that prediction for the subsequent step was most relevant to the initial three step inputs. Overall, the operation of opening and closing of wells, changing the size of chokes, and variations in daily production time can be considered in our LSTM deep learning model, which provides more reasonable results.
      原文链接:
    • NSTL
    • Elsevier

    The synergistic effect of Fe2O3/SiO2 nanoparticles concentration on rheology, wettability, and brine-oil interfacial tension

    Hassan, Yarima MudassirGuan, Beh HoeChuan, Lee KeanHamza, Mohammed Falalu...
    9页
    查看更多>>摘要：Various nanoparticles (NPs) have been discovered as revolutionary agents of change in reservoir properties such as rheology, interfacial tension (IFT), and surface wettability that could lead to enhanced oil displacement. In recent years, Silicon dioxide (SiO2) and various metal oxide NPs have recorded successes in oil recovery, thus, understanding composites of NPs fluids is anticipated to provide unprecedented outcomes. The present study is aimed at evaluating the synergy impact of the NPs concentrations of Fe2O3/SiO2 on rheology, IFT, and rock surface wettability. The composite of Fe2O3/SiO2 was firstly synthesized and characterized to determine its physical and chemical properties. Subsequently, nanofluids of Fe2O3/SiO2 were prepared at different concentrations using brine as a fluid dispersant phase and investigated on the rheology, IFT, and wettability at 60 degrees C. The results have shown that the dispersion stability of the Fe2O3 NPs was found to have increased from -11 mV to -38 mV when SiO2 NPs were introduced and led to an increase in the viscosity of the composite fluids from 0.88 cP to 1.95 cP. The base case IFT (brine/oil system) was observed to be 17.39 mN/m, and upon introduction of the Fe2O3/SiO2 composite, the IFT significantly reduced to 0.21 mN/m as a result of the high attachment of the NPs at the oil/fluid interface. Furthermore, combining SiO2 with the Fe2O3 has facilitated the adsorption capacity of the NPs composite leading to the spreading of the nanocomposite fluids on the surface of sandstone which eventually alters the wettability from 140.65 degrees to 26.23 degrees. The study has shown the synergy effect of composite NPs which resulted in reducing the IFT and wettability by 98 and 81% respectively in advance of 50-60% reductions commonly observed when individual NPs have been used.
      原文链接:
    • NSTL
    • Elsevier

    Numerical investigations on rock breaking mechanism and parameter influence of torsional percussive drilling with a single PDC cutter

    Xi, YanWang, WeiZha, ChunqingLi, Jun...
    14页
    查看更多>>摘要：Torsional percussive drilling tool was designed to reduce the risk of stick-slip and improve drilling efficiency, but there are few studies on the influence of torsional impact parameters, including amplitude, frequency, waveform, on the rate of penetration (ROP) while drilling the hard rock. The design of the torsional percussive drilling tool was proposed, and the mathematical model of torsion hammer movement was developed, the Riedel-HiermaierThoma (RHT) rock dynamic material model was applied to analyze the rock-breaking process of the tool. A numerical model of hard rock cutting with a single polycrystalline diamond composite (PDC) bit cutter was established, the influences of amplitude, frequency, time parameters, and waveforms on the penetration depth of the PDC bit cutter were analyzed in the process of torsional percussive drilling. The results showed that the numerical simulation results were in good agreement with the indoor test results, which verified the correctness of the numerical simulation. Compared with conventional drilling, the penetration depth of torsional percussive drilling was increased by 20.0%, and the cutting debris particles were smaller, which was conducive to improving ROP and reducing stick-slip vibration of the bit. With the increase of the peak value of torsional percussive amplitude, the penetration depth of the cutter first increased and then decreased. When the ratio of torsional impact load to axial static load was 1.0, the penetration depth of the drilling cutter reached a maximum. When the torsional impact frequency was 40 Hz-100 Hz, the penetration depth decreased with the increase of the frequency, but the diameter of cuttings became smaller and smaller, which was conducive to cleaning the wellbore with drilling fluid. The latter has the highest rock-breaking efficiency compared with triangular, sine, and rectangular waves. Finally, suggestions are given on how to adjust these parameters by adjusting engineering parameters and tool structure parameters to optimize the efficiency of the torsional percussive drilling tool.
      原文链接:
    • NSTL
    • Elsevier

    A comparative study of dispersed and grafted nanofluids of graphene nanoplatelets with natural polymer in high salinity brine for enhanced oil recovery

    Hamdi, Sinan S.Al-Kayiem, Hussain H.Alsabah, Mohammed S.Muhsan, Ali S....
    17页
    查看更多>>摘要：Polymer flooding as one of conventional chemical enhanced oil recovery (C-EOR) techniques has high potential for declining the mobility ratio and improving oil recovery. The degradation, toxicity, and cost are inherent restrictions in polymer performance at high salinity and high temperature. Recently, incorporation of nanoparticles with a polymer to produce polymeric nanofluids has acquired a great interest as the newest trends of development in nanotechnology for EOR processes. In this study, a comparative evaluation of functionalized graphene nanoplatelets (GNPs) were prepared by two different methods of mixing and grafting with natural Polymer of Gum Arabic (GA). These methods aimed to improve the dispersion stability of the nano-additives in high salinity brines and high temperature conditions for promising alternative C-EOR agent. The physiochemical properties of the functionalized GNPs were characterized by Fourier transform-infrared spectroscopy, Raman spectroscopy, and transmission electron microscope. The zeta potential, dynamic light scattering, and optical absorbance were employed to evaluate the effective dispersion stability of the prepared nanofluids in high salinity concentration 3 wt% and temperature at 90 degrees C. The laboratory results indicated that the dispersion and rheological properties revealed a stable dispersibility of Polymer grafted GNPs (PG-GNPs) in high salinity brine even with high temperatures compared to Polymer dispersed GNPs (PD-GNPs) at low concentration 0.05 mg/mL. However, it was observed that the nature of functionalized GNPs with GA has a significant role in increment the capillary number via reducing the value of interfacial tension (IFT) and modification the wettability of pores surface inside the heterogenous micromodel. The core flooding findings of nanofluids injection in the mid permeable sandstone porous media showed that oil recovery enhanced by around 17% and 5% at 0.05 mg/mL of PG-GNPs and PD-GNPs, over the conventional water flooding. Consequently, the overall results of PG-GNPs exhibited better performance compared to PD-GNPs due to successful GNPs layers exfoliation which led to stable dispersion with the same concentration of 0.05 mg/mL at reservoir conditions.
      原文链接:
    • NSTL
    • Elsevier