Journal of Petroleum Science and Engineering最新文献

Due to many biological and technical applications, including microelectronics, heat exchangers, cancer therapy, process industries, solar collectors and power production, researchers have been more interested in the mechanism of heat transfer involving nanomaterials. A contemporary method to increase the thermal conductivity of various cooling fluids is the use of nanomaterials. Many researches suggest that the thermal conductivity of nanoliquids; solid nanoparticles combined with a base fluid, is expressively greater than that of conventional fluids. This work presents the theoretical investigation of magnetohydrodynamic stagnation point flow of non-Newtonian nanofluid flow past flat plate. The applications of solar radiation towards water-based copper nanoparticles are highlighted in this study. The system of PDEs is transmuted into the system of ODEs by mean of suitable similarity variable. Analytical solution of the present analysis has been performed with the help of HAM technique. The impacts of physical factors on the flow profiles, skin friction coefficient, heat, and mass transfer rates are calculated. It is significant to note that the default concentration is weighted by 4% throughout this analysis. Also in this analysis, we examined the temperature and heat transfer rate for the presence and absence of solar radiation. It is found that the greater nanoparticles volume fraction of the water-based copper nanoparticles has accelerated the flow profiles for the absence of magnetic field. However, for the presence of strong magnetic field, the velocity, and temperature of the water-based copper nanoparticles have significantly reduced. Due to the incidence of Lorentz force, the velocity of the water-based copper nanoparticles has deteriorated, while the temperature profile has augmented. It is found that the solar radiation has always dominant impression on temperature of the water based copper nanoparticles.

Drilling mud acts as an important primary barrier during the well construction phase, while the integrity of cement sheath is critical throughout the life cycle of the well. The mud-spacer-cement interactions highly affect the long-term integrity of the cement sheath and in other words the well integrity. Even today, the spacers are not capable of displacing all the drilling mud present in the wellbore before performing cementing operations and the cement slurry is contaminated with a small amount of drilling fluid and/or spacers. Oil based mud (OBM) is highly preferred over water-based mud (WBM) as a drilling fluid when drilling in challenging environments, but with current push for more environmentally drilling fluids the Water Base Muds (WBM) are preferred.

The detrimental effects of high OBM contamination (>5%) on the mechanical and rheological properties of API Cement slurries have been fairly studied in the previous decade. This study focuses on the strength development of low OBM contaminated (0.8%, 1.6%, 3.2%, 6.3%) API Class H cement slurries cured for up to 28 days at ambient temperature as well as the elevated temperature of 75 °C. The Ultrasonic Pulse Velocity (UPV) was measured by performing the non-destructive tests before performing the destructive tests which measure the actual Unconfined Compressive Strength (UCS). Based on the 141 samples tested in this study, even for 0.8% OBM contamination the strength of Class H cement samples cured for 7 days at 75 °C was reduced by 23%, and for 3.2% OBM contamination it was reduced by 39%. Novel correlations of UCS vs time and UCS vs UPV were developed to accurately simulate the downhole conditions and predict the long-term integrity of the wellbore cement. A reliable dataset for developing cement data repositories was established which also can be merged with existing databases.

To explore the rock-breaking efficiency and vibration characteristics of polycrystalline diamond compact bit in heterogeneous rock, this paper analyzes the typical vibration characteristics and failure modes of polycrystalline diamond compact bit. Then, the transverse combination of rocks was innovatively used to simulate a situation of soft-hard interbedded formation, forming three kinds of transversely combined heterogeneous rock samples with different degrees of heterogeneity. We conducted a series of laboratory rock-breaking experiments and the experimental results indicate that rock heterogeneity greatly impacted vibration acceleration, lateral bending moment, rate of penetration, and drilling trend. With the increase in weight on bit and rotation speed, the rate of penetration gradually increases. However, the tangential, axial, and radial vibration acceleration amplitude of the bit all increase simultaneously, which implies that the vibration impact generated by rock-bit interaction increased. The difference in the cutting depth of the drill bit in the heterogeneous formation causes low efficiency. The stronger the heterogeneity, the lower the rate of penetration. Rock heterogeneity, especially the rock properties of the combined rock samples, significantly impact acceleration and lateral bending moment. As rock heterogeneity increased, the bit acceleration increased significantly, intensifying the bit vibration; the lateral bending moment increased slightly, but its fluctuation intensified. The strength difference of heterogeneous rock causes eccentricity, the harder rock exerts greater force on the bit, causing the bit to deviate from the original trajectory. The greater the difference, the greater the eccentricity, consequently, the more the bit shifts to the softer side. Adjusting rotation speed and depth of cut control may be feasible solutions to solve the problem of low drilling speed and high vibration in heterogeneous formation. It is hoped that the findings in this paper will be helpful to explore a reasonable way to reduce vibration while maintaining high efficiency.

Chang 7 shale reservoir of Ordos Basin has characteristics of low porosity, ultra-low permeability, and low formation pressure coefficient. After hydraulic fracturing, the production of shale oil declines rapidly, and it has no solutions to replenish the formation energy. Currently, a nano variable-viscosity slickwater (named: NSI) is being used in the field for fracturing production. Compared with conventional fracturing fluid systems, the NSI system can increase production of oil wells by more than 4 times, and its economic benefits are very remarkable. The lab experiment shows that NSI system after the gel breaking has ability of enhanced imbibition oil recovery (EIOR), which may be an important stimulation mechanism of the NSI system. However, the contribution of EIOR to oil production is still unclear, and the corresponding mechanism and model are still lacking. Therefore, the fracturing parameters of Changqing Chang 7 reservoir were firstly optimized without considering the imbibition, and two wells were used to carry out field experiments with NSI and conventional slickwater. Then, commercial software is used to predict oil production. It was found that the actual production was higher than the predicted production. To explain this phenomenon, the effect of imbibition on enhanced oil recovery was investigated experimentally under reservoir temperature and pressure. The NMR T₂ spectrum was quantitatively analyzed to clarify the variation of oil and water distribution in different pores of core. The results showed that capillary force was dominant in the small pores of core, and small pores were the main positions of EIOR. Water film was formed in large pores, which increases the migration resistance of the liquid, and allowed gravity to play an obvious role. Finally, based on the modified Aronofsky index model, an EIOR model suitable for the Changqing Chang 7 reservoir was proposed, which achieved a better match between actual production and simulated production of horizontal wells.

The petrophysical and elastic properties of the carbonate rocks controlled by strike-slip fault are still poor understood due to their significant complexities and strong heterogeneities, causing challenges for the exploitation and development of these carbonate reservoirs. To better comprehend the heterogeneity of petrophysical and elastic properties of the fault-controlled carbonate rocks, a small carbonate strike slip fault zone is selected, which is located in Yangjikan section in the Tarim basin. We combine the geostatistical, microscopic observation, petrophysical and ultrasonic analyses to characterize and understand the complexities and heterogeneity of petrophysical and elastic properties with different distance to the main fault core. The results show significant complexities and heterogeneities of petrophysical and elastic properties, and the variations of rocks drilled from the fault core are relatively drastic compared to those from the damage zone. The equivalent pore aspect ratios of the rocks are calculated from the differential effective medium theory, the values in the fault core are much higher compared to those from the damage zone, which can discriminate the pore network architectures and can represent reference for determination of the boundary of fractured damage zone. The controlling factors on the heterogeneity of the petrophysical and elastic properties for the selected fault zone are discussed, which mainly include the influence of fault structure position on fracture development, fluid selective filling on effective fracture and pore development, and the sequence on pore development. The results can contribute to the recognition and prediction of the petrophysical and elastic properties and hydrocarbon exploration in carbonate strike-slip fault zone in the Tarim Basin, and can provide reference for the construction of integrate multiscale heterogeneities models.

We apply Massively Parallel Interface for MPFA-O scheme with state-of-the-art Operator-Based Linearization (OBL) approach for multiphase flow in porous media. The implementation of MPFA-O scheme enhances the modelling capabilities for non-K-orthogonal mesh. A fully implicit scheme is applied to guarantee the stability of solutions when a mass-based formulation is involved to keep the flexibility of the framework for general-purpose reservoir simulation. As the MPFA-O introduces more non-zeros elements in the Jacobian matrix than the traditional TPFA, massively parallel computations via Message Passing Interface (MPI) in this work help to guarantee competitive computational efficiency for high-fidelity geological models. Concerning the Jacobian assembly hassle, we apply the OBL approach which introduces operators combining the fluid and rock properties in the conservation equations and discretizes the operators in the physical parameter space. By computing values and derivatives of the operators via a multilinear interpolation, the assembly of Jacobian matrix and residual vector could be drastically simplified. Another benefit of the OBL is that by only evaluating operator values on the predefined nodes in the physical parameter space, the overhead related to complex phase behavior and property evaluation is significantly reduced. In the end, we present several benchmark cases to rigorously demonstrate the accuracy, convergence, and robustness of the framework and two challenging field-scale cases to further prove its computing performance and parallel scalability.

In this study, Modified Laponite with lyophobic wettability was synthesized as a multi-functional additive to solve instability of emulsions, rheological deterioration, and wellbore instability of oil-based drilling fluid. Properties and its influence on emulsion stability, rheological behavior and plugging property were investigated. The results showed that Modified Laponite was in a shape of sheet layer and had micro-meter length and nano-meter thickness which was in match with the diameter of shale pores. And it was proved to be resistant to approximately 450 °C by thermogravimetric analysis measurement. Mechanism analysis revealed that Modified Laponite could stable the oil-based drilling fluid through four sections. Firstly, Modified Laponite with lyophobic wettability could promote its existence in the interface of brine/mineral oil. Secondly, Modified Laponite could decrease the interfacial tension from 32.8 to 13.5 mN/m to maintain the emulsion particles in a small size for a long time then to ensure the emulsion stability. Thirdly, Modified Laponite could enhance the shear-thinning rheological behavior which could maintain the rheological stability and enhance the sedimentation stability in ultra-deep reservoirs with high temperature and high pressure conditions. Fourthly, Modified Laponite could plug the shale pores effectively by preventing pressure transmission and enhancing shale compressive strength, and decrease the filtration volume of oil-based drilling fluid from 7.4 mL to 2.6 mL after aging at 180 °C for 16 h to stable the wellbore. Therefore, Modified Laponite was a multifunctional additive to stable the emulsion, enhance the rheological stability and strength the wellbore stability, which could ensure the application of oil-based drilling fluid in drilling process of ultra-deep reservoirs.

Well drilling, completions, stimulation, and enhanced oil recovery operations induce downhole conditions that may negatively impact the integrity of the annular seal and consequently hinder zonal isolation. Thus, the ability to accurately quantify the evolution of the annular seal in response to the prevailing downhole environment is critical for the optimal design of the annular barrier for the life of a well. Thanks to increased accessibility and recent advancements in computing power and techniques, X-ray computed tomography has gained popularity as a non-destructive analysis method in materials science and geomechanics due to its ability to reveal details about the interior volume of objects in real-time without physical disassembly.

Therefore, in this study, a novel apparatus is presented for the construction of a lab-scale wellbore, with the purpose of simulating downhole processes while simultaneously monitoring wellbore elements of interest in real-time via x-ray computed tomography. The benefits of this novel setup for wellbore integrity are demonstrated via applications to two test cases: the mechanical evolution of annular cement under stresses induced by cyclic water injection as a function of the mechanical properties of the cased and cemented wellbore system; the evaluation of nano magnesium oxide performance as an additive for autogenous shrinkage mitigation in annular cement.

The results of the studies presented illustrate the benefits of combining x-ray computed tomography with lab-scale wellbore process simulations. The results of the cyclic water injection study suggest that residual strain in the cement is the major factor in annular seal degradation under cyclic downhole pressure fluctuations. Nano magnesium oxide is also shown to be very effective in preventing autogenous shrinkage of Class H cement. However, more study is required to characterize its effectiveness in a wider range of cement formulations. Finally, suggestions are offered on how to improve the experimental procedure presented while future potential applications of the apparatus are discussed.

The eastern Tunisian margin is considered an Upper Cretaceous and Eocene petroleum province. It has been affected by Mesozoic rifting and Cenozoic compression. Several oil and gas shows and accumulations have been discovered in Upper Cretaceous carbonates within structural anticlinal closures. These anticlinal highs represent inherited rift platform horsts with hiatuses, unconformities and sediment erosion. Seismic sequence stratigraphy and seismic tectonic analyses of Mesozoic and Cenozoic horizons, delineate the control of deep-rooted transtensional and transpressional Flower structure fault corridors, intruded by Upper Triassic salt. Petroleum system modelling and time events chart reconstruction of real and pseudo-wells, indicate that Cretaceous source rocks maturation and hydrocarbon generation began during Late Cretaceous with expulsion occurring from Eocene to Pliocene times. Hence, Upper Cretaceous petroleum system dynamics is intimately linked to basin geodynamics; where hydrocarbon migration pathways could follow the migration, rotation and tilting of platform and basin blocks. The volume of Lower Fahden and Bahloul source rocks expelled hydrocarbons from the basin kitchens, is much greater than that found in the drilled anticlinal axis. These hydrocarbons could have been trapped along the platform-basin border flanks and may not have reached the highest position on the anticlinal crest closure. Such pathways explain the unaccounted-for hydrocarbon volumes. These volumes could be trapped along the faults seal branches, unconformities, pinchouts as well as in the evidenced progradational and reefal system tracts sequences in the flank borders of the platforms. These traps could represent new exploration targets as potential structural and stratigraphic plays.

Subsea water separation (SSWS) is a promising cutting-edge technology in handling specific problems related to offshore development, but the close evaluation of SSWS performance is quite lacking. This work develops an integrated production modeling (IPM) approach to comprehensively quantify the effect of SSWS both from technological and economical perspectives. A fully-implicit integrated production model is proposed, which assembles 3D reservoir equations and pipeline network equations together and seeks for simultaneous solutions. The feature of simultaneous hydro-thermal solution provides a remarkable value in the analysis of flow assurance issues related to wax deposition in the subsea flowlines. The indexing and mapping frameworks make the model prone to configuring different scenarios, both in temporal and spatial dimensions. A case study is presented to analyze the performance of SSWS under four subsea configurations in a pre-salt deepwater condition by three quantitative indicators: NPV, oil recovery, and wax-free index. Results show that subsea water separation has the potential to increase final oil recovery and project NPV for a clustered well system, while limited benefits shall be expected in a satellite well configuration. Also, higher risk of wax deposition is observed in a satellite well configuration compared to a clustered well system. The IPM approach, together with an economic model, provide decision makers with a way to estimate the break-even price on the investment of a subsea water separation station. The methodology proposed in this work also provides a guide in future assessment of other potential subsea technologies.