首页期刊导航|Journal of Petroleum Science & Engineering
期刊信息/Journal information
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
正式出版
收录年代

    Oil charging pore throat threshold and accumulation effectiveness of tight sandstone reservoir using the physical simulation experiments combined with NMR

    Guangdi LiuZhe CaoChaozheng Li
    12页
    查看更多>>摘要：Tight oil as a significant part of unconventional resources is now considered as one of most important alternative resources. Oil accumulation mechanism is still a research focus for the tight oil. Therefore, it is important to study the effectiveness of micro-nano pore system to oil charging and accumulation. Taking the Chang 7 tight sandstone reservoir of the Ordos Basin as an example, the physical simulation experiment of oil charging is applied to study the pore throat threshold of tight sandstone reservoir under the different charging force using the nuclear magnetic resonance (NMR) combined with displacement techniques. The relationship between charging force and pore throat radius threshold (Rth) can be established when combined with the pore throat distribution derived from MICP. In addition, the effectiveness of oil accumulation for the different type tight sandstone reservoir is also discussed. The result shows that the Chang 7 tight sandstone reservoir is divided into four groups based on pore structure and petrophysical property (porosity and permeability). In the physical simulation experiment, the oil saturation growth trend can be roughly divided into three groups;; uniform growth model, slow growth-stable model, fast-slow growth model. This result indirectly reflects the heterogeneity of pore structure. There is a power function relationship between the charging force and Rth of oil charging, which can be used to calculate the effective accumulation space and further determine the accumulation effectiveness. The effectiveness of oil accumulation changes with the increase of the charging force;; the effective accumulation space increases with the charging force, which causes that the reservoir (usually not including type III) gradually transits from ineffective accumulation to effective accumulation. That is, the charging force coupled with pore throat radius controls oil charging and accumulation. For the Chang 7 tight oil accumulation, the effective pore throat radius threshold of oil charging is about 0.1 jim and thus only the type I and Hi reservoirs can become the effective tight oil reservoirs, which is the main target of tight oil exploration. This result not only puts insight into the tight oil accumulation mechanism but also plays an important role in the tight oil exploration of Yanchang Formation in the Ordos Basin.
      原文链接:
    • NSTL

    Investigation of fluid flow mechanisms in fractured porous media using a Laplace transformation coupled embedded discrete fracture protocol

    Qian SunJianchun Xu
    15页
    查看更多>>摘要：Numerical simulation of fluid flow in fractured porous media is a challenging topic due to the intensive computational overhead brought by the complex and heterogeneous characteristics of fracture networks. In this paper, Laplace Transformation coupled Embedded Discrete Fracture Model (LTEDFM) protocol is proposed to simulate the fluid flow dynamics in fractured porous media, which employs the Laplace transformation to substitute the backward temporal Euler differentiation by a semi-analytical solution. Comparing to the conventional EDFM models, the LTEDFM model is Newton's iteration free, and the solution would be independent of the temporal discretization (progressive time-steps). Results of various numerical experiments demonstrate that the proposed LTEDFM is a more computational robust solution protocol to simulate the flow dynamics of undersaturated oil reservoirs in fractured porous media comparing to other versions of EDFM models. Moreover, the proposed LTEDFM can be employed to simulate the field responses of heterogeneous and anisotropic systems, reservoirs with the existence of complex fracture networks and reservoirs developed using multiple hydraulic fractured wells.
      原文链接:
    • NSTL

    A new theory for flow computations in a large class of anisotropic media with applications to well productivity modeling

    Thormod E. JohansenJie Cao
    14页
    查看更多>>摘要：A new theory for calculation of fluid flow in laterally isotropic, spatially anisotropic permeable media is presented. This theory is capable of quantifying fluid flow in such media without the use of cumbersome tensorial calculations involving non-zero off-diagonal elements. Using this theory, we derive analytical models for well productivity of deviated wells in such media, for both steady-state and semi-steady-state flow. The theory developed in this paper relies on a spatial volume preserving transform composed of two rotations and two linear coordinate deformations. This transform is designed such that a prefixed direction aligns with one of the coordinate axes of the transformed space. Furthermore, the transformed medium is isotropic in planes perpendicular to the prefixed direction, and the transformed permeability is diagonal. As a bi-product, the new theory developed in this paper also provides closed formulas for directional permeabilities. These formulas are expressed with a different set of parameters than well known classical formulas for directional permeabilities. Since both approaches are fully analytical without any form of approximation, it is imperative that these formulas are proven identical.
      原文链接:
    • NSTL

    Density stability estimation method from pre-stack seismic data

    Zhaoyun ZongQjanhao Su
    19页
    查看更多>>摘要：As one of the most important elastic parameters in seismic exploration, density plays an important role in lithology identification and hydrocarbon indicator. Based on the approximate Zoeppritz equation, the density term is usually estimated using AVO/AVA (Amplitude variation with offset/incident angle) inversion. However, the small contribution of density to the reflection coefficient or the strong correlation with other parameters in the approximate equation renders the density estimation tough. By analyzing the contribution of density to reflection coefficient in different approximate equations, Aki-Richards is finally selected as the inversion equation, in which the density term has a higher contribution to the reflectivity. The conventional inversion approach is to invert several parameters simultaneously on the basis of approximate equation. The same convergence criterion is used for the estimation of the three parameters, but the density estimation error fails to converge to the minimum due to its small sensitivity, which makes density inversion unstable. Furthermore, the conventional inversion methods involve the inverse of large matrix, which also reduces the stability of density estimation. Therefore, a new form of Aki-Richards approximate reflection equation is derived on the assumption that the inverse of coefficient matrix exists. The reflectivity of elastic parameter is independently expressed as the weighted superposition of seismic reflection coefficients at different incident angles. Then utilizing well logging data and seismic reflection coefficient estimated by elastic impedance inversion as constraints, the inverse of coefficient matrix in inversion equation is estimated directly, which avoids inverse of large matrix and improves the precision of density estimation. In physical, the weighted coefficients directly reflect the contribution of elastic parameters reflectivity to seismic data. Finally, different experimental examples show that proposed method can stably estimate density term.
      原文链接:
    • NSTL

    Discovery of the Lower-Middle Jurassic high potential source rocks based on the geochemical investigation from the Indus Basin, Pakistan

    Fahad AliShiqi ZhangSaeed Abbas
    10页
    查看更多>>摘要：The Lower to Middle Jurassic sedimentary succession of the Indus Basin, Pakistan represents thick strata of shale, siliciclastic and carbonate rocks. The shale is subjected to the experimental methods of total organic carbon contents (TOC), rock-eval?, vitrinite reflectance, and x-ray diffraction with clay mineralogy for identification of high potential source rock. This set of black shale having well-defined kerogen types I and II, an abundance of organic matter >2%, HI > 150 or 200 mg HC/g TOC, Tmax < 465 °C, good maturity such as 1.3~(-2).0 Ro%, thermal alteration index >2, and spore color index >5, and illite-smectite clay is strong enough (60-80%) to produce hydrocarbon. Furthermore, the stratigraphic thickness is < 100 m in studied strata in a depth of 3500-4500 m in the Indus Basin feasible for future exploration. The chemical composition of black shale is siliceous mudstone, calcareous mudstone, argillaceous mudstone, and siliceous marlstone. The cross plot of OI versus HI and Tmax versus HI shows mature types II and I kerogen while the cross plots of TOC versus Si + S2 with TOC versus generative potentials (GP) showing good to high potentials of indigenous hydrocarbons. The plotting of the Tmax versus productive index (PI) exhibits that the kerogen mostly lies in the mature zone, having the capacity of oil generation. Besides the geochemical properties, the studied rock is thick and widely disturbed across the Indus Basin deposited under the dysoxic-anoxic setting. Moreover, the Lower to Middle Jurassic strata are correlated with the equivalent stratigraphic formations in India and China for their importance in the regional context.
      原文链接:
    • NSTL

    Pressure transient behavior in a multilayer reservoir with formation crossflow

    Jing LuMd Motiur RahmanErlong Yang
    13页
    查看更多>>摘要：This study proposes a new solution to the pressure transient behavior for a uniform-flux with a fully penetrating vertical well in a multilayer reservoir with formation crossflow. The general problem of pressure transient in multilayer reservoirs, in which any two adjacent layers are crossflowing in the formation, is solved analytically. The solution is presented for an infinite-acting system with no wellbore storage or skin factor effects. This analytical solution is obtained using Laplace transform, double Fourier transform, and Green's functions method. This solution provides an accurate and fast tool to;; evaluate a vertical well performance in a multilayer reservoir, and estimate the effects of formation properties on pressure behavior at locations both far away from and around the well. Based on the solution, the pressure of the vertical well, which produces with a constant rate in the multilayer reservoir, can be examined in detail. An expression of dimensionless crossflow coefficient is obtained by solving a symmetric tri-angular matrix equation. Based on the solution, it is verified that the dimensionless crossflow coefficient is not constant but behavies as a function of the time and distance away from the wellbore. When producing time is sufficiently long, crossflow will cease to exist and crossflow coefficients are equal to zero, which means there are no effects of adjacent layers on the pressure drop of each layer. These findings indicate that each layer produces independently.
      原文链接:
    • NSTL

    Influence of high permeability subdomains on steam injection performance in heavy-oil reservoirs

    L.C BatistaJ.V.O. BecharaE.A Araujo
    10页
    查看更多>>摘要：Steam injection (or steam-flooding) can be considered the most frequent thermal recovery method used in the oil industry due to its added value in terms of heat concentration, availability, and moderate cost. Given the large extent of heavy oil reservoirs worldwide, many of them endowed with high permeability subdomains (HPSs), the numerical evaluation of steam-flooding efficiency has become relevant for understanding flow aspects in this type of formation. In view of the scant literature dealing with this issue, this paper is intended to evaluate the heavy-oil recovery factor in a model composed by HPSs subjected to steam injection over a period of 16 years. We investigated the impact of steam injection rate, the influence of multiple embedded subdomains, and the effect of injection well's flow directionality and HPS skewness. To this end, we resorted to numerical triphasic pseudo-compositional flow simulations carried out with CMG STARS? software over a model with rock-fluid properties similar to the Alto do Rodrigues Field's (Brazil's northeastern region). The outcomes indicate that, depending on the layout, number, and position of the HPSs, the ultimate oil recovery may increase or decrease. In particular, one observes that with equal increments of gas injection rates, the recovery factor can improve by up to 10%. Moreover, we emphasize that the growth or decay of the recovery factor has no apparent linear relationship with the testing parameters. Such findings are helpful for guiding steam-flooding strategies in revitalization projects of mature fields.
      原文链接:
    • NSTL

    Quantitative assessment approach to assess benefits of subsurface safety valves and tubing and packer systems in depleted reservoir and aquifer gas storage wells

    SlawekWineckiStephen NowaczewskiKathryn L Johnson
    12页
    查看更多>>摘要：The Battelle Memorial Institute, Sandia National Laboratory, and Nova Northstar LLC, jointly carried out two projects, sponsored by the Pipeline and Hazardous Materials Safety Administration, assessing the roles of subsurface safety valves and tubing and packer systems in depleted reservoir or aquifer wells used for underground gas storage. The assessment was based on the American Petroleum Institute 581 method and on the storage well-specific model created by the 2017 Joint Industry Task Force organized by the UGS industry in response to the Aliso Canyon gas leak. The model was expanded to capture the specific functionalities of safety valves and tubing and packers, as well as to account for workover risk associated with monitoring and maintenance of such devices. The main conclusion of the two projects is that the application of safety valves and/or tubing and packer systems can reduce risk in some, but not all, gas storage wells. Gas storage wells with low initial risk, as measured by a likelihood of a loss of control event and by a projected consequence of such event, would generally not benefit from installation of new safety systems. In fact, the risk may be increased due to risk of more frequent and more complex workover operations or due to deliverability impairments. For some wells, the initial risk is such that the application of a safety valve or a tubing and packer can substantially decrease risk, specifically reduce consequences of loss of control events. Wells with inherent or initial risk, particularly driven by high likelihood of failure, would see risk reduced by the application of a safety valve or a tubing and packer, however, remaining risk are unacceptably high. An effective way to assess the applicability of these safety devices is to apply quantitative risk models, specifically models that evaluate probabilities/likelihood and consequence of accidents.
      原文链接:
    • NSTL

    Experimental and numerical study of cuttings transport in inclined drilling operations

    Mohammad Mojammel HuqueMohammad Azizur RahmanSohrab Zendehboudi
    27页
    查看更多>>摘要：Directional drilling has become popular in recent decades in both onshore and offshore operations due to reduced drilling costs and improved recovery. In a directional well drilling operation, drill cuttings tend to settle down at the lower side of the inclined annular section. If the generated cuttings are not removed from the hole section properly, it causes a cuttings bed formation in the annular section. Different drilling related problem such as poor rate of penetration, excessive torque and drag, increase differential sticking often associated with a poor hole cleaning which eventually lead to increase in non-productive time (NPT). Therefore, the success of inclined well drilling operation largely depends on effective cleaning of drill cuttings from the annular section. A variety of parameters, including the fluid rheology, mud velocity, cuttings size, drill pipe rotation and drill pipe inclination generally influence the cuttings transport performance. Optimization of these drilling parameters is crucial to ensure proper hole cleaning. In this study, a Computational Fluid Dynamics (CFD) model for the inclined well section is used to investigate the cuttings transport efficiency (CTE). An Eulerian-Eulerian multiphase flow model is proposed and validated with lab scale experimental data. The experiments were performed in a 6.16-m-long annular test section having an outer pipe diameter of 4.5-inch and an inner pipe diameter of 2.5-inch. The setup is equipped with Electrical Resistance Tomography (ERT) system to measure the instantaneous solid volume fraction and a visualization section. A non-Newtonian Heschel-Bulkley (HB) fluid was used as drilling mud and solid glass beads of 2.50 mm-3.00 mm were used as cuttings in the experiment. This study shows a good agreement in visualization of mechanistic three-layer model of cuttings transport in terms of ERT data from experiment and CFD simulation. The validated CFD model is used to perform 5-Factors factorial design and analysis of variance (ANOVA) study. ANOVA shows that the interaction effects of mud velocity-cuttings size, mud velocity-inclination are statistically significant. Finally, this study proposed a statistical model to estimate the CTE of an inclined well considering the two factor and three factor interactions among the variables. Also, the model shows that drill pipe rotation has negligible effect in improving cuttings transport efficiency in the inclined well. The proposed model also reveals that cuttings size and fluid velocity account for 78% contribution in the transport efficiency for an inclined well. Furthermore, an Artificial Neural Network (ANN) method is used to verify the contribution of lower order interaction in the statistical model. Though empirical model shows few lower order two factor interactions (fluid rheology-cuttings size, fluid rheology-inclination), and three factor interactions (velocity-cuttings size-inclination, fluid rheology-cuttings size-inclination);; ANN model shows that lower order interaction are significant in model prediction and should not be ignored. The findings of this study can help in better understanding the interaction behaviour among drilling parameters and optimized cuttings transport efficiency in the inclined drilling operation for a wide variety drilling parameters.
      原文链接:
    • NSTL

    Developmental characteristics and formational stages of natural fractures in the Wufeng-Longmaxi Formation in the Sangzhi Block, Hunan Province, China;; Insights from fracture cements and fluid inclusions studies

    Gang ZhaoZhijun JinWenlong Ding
    20页
    查看更多>>摘要：The developmental characteristics and formational stages of natural fractures are of great significance for shale oil and gas accumulation in complex structural areas. We determined the developmental characteristics and formational stages of fractures in the Wufeng-Longmaxi Formation in the Sangzhi Block, Hunan Province, China based on outcrops, cores, optical microscopy, cathodoluminescence, scanning electron microscopy, energy spectrum analysis, fluid inclusion homogenization temperature, micro laser Raman spectrum analysis, and acoustic emission analysis. Furthermore, we deduced the possible fracture formational depth, filling time, and stress magnitude of structural fractures in rocks, and established the development model of structural fractures of time series. The results show that the Wufeng-Longmaxi Formation fractures can be divided into tensile fractures, compression-torsion fractures, and strike-slip fractures in terms of the combination characteristics of fracture plane and the roughness of fracture plane. The fractures mainly occurred in the late Yanshanian-Himalayanian period after the violent uplift. In the process of burial-hydrocarbon generation, it experienced at least six stages of repeated process of splitting, healing, re-splitting, which reflected the periodic release of local stress caused by the continuous westward push of Xuefeng uplift. The microcracks of different periods have obvious differences in orthogonal polarization and cathodoluminescence reflection characteristics. The cathodoluminescence spectrum ranges from orange red to bright yellow, and some even do not glow, which is a comprehensive performance of mineral filling composition, crystal size, crystallization degree and alteration degree. The gas generated in the early stage are easy to enter the early opened fractures. With the continuous opening and healing, the shale gas has a continuous dynamic process of enrichment, dispersion, re-enrichment, and re-dispersion, which affects the distribution and preservation of shale gas.
      原文链接:
    • NSTL