84 research outputs found

    SIMULATION STUDY ON WATERFLOOD FRONT: BLOCK HADE OF TARIM OILFIELD IN NORTHWEST CHINA

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    Block Hade consist of a deep thin sandstone reservoir of two sub-layer reservoirs. The thickness is about 1.5 m for each layer. The two-layer “staircase” horizontal well is used for recovery. In order to determine water displacement front and edge water movement, tracer test is conducted in the reservoir. But the cycle of field tracer monitoring is about 150-360 days. This prevented the efficient monitoring of waterflood swept area and waterflood advance direction and velocity, after the cycle of tracer monitoring. Conservation of mass with respect to tracer flow and history performance matching of tracer enabled the study of water-flood front and edge-water advance. The simulation result is basically consistent with the monitored field tracer results. Therefore, numerical model can be used to conduct a longer monitoring period. It can make up for the disadvantage of the complexity of the tracer monitoring setup, its implementation, and time-consuming monitoring cycle. The water-flood front, water-flood swept area, advancing velocity and the predominant water injection direction can be obtained. Furthermore, it is possible to evaluate and predict the injection-production well interaction and can also provide a reliable basis to deploy reasonable flood patterns to enhance oil recovery

    Experimental Study of Darcy and Non-Darcy Flow in Porous Media

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    A simple experimental set-up is used to validate capillary-tube models of flow in porous media for (non-) spherical particles and coarse grains of particular/specific mesh sizes. Of the two models used, one model characterizes the structure of the media apart from particle diameter or equivalent particle diameter for non-spherical objects compared to the other model. The magnitude of computed tortuosity for particles/grains studied is in order, however, that of the spherical particles was slightly higher than published values for spheres. Likewise, the ratio of dynamic to static specific surface area was below anticipated and known results in literature. For the non-spherical particle that was approximated as a half-oblate spheroid, the possible error in computed volume and surface area may be the reason for the deviation of computed equivalent diameter from the effective diameter obtained by fitting Ergun correlation to experimental result. The deviation of computed results based on the conducted experiment may in fact be due to error in appropriately fitting straight line to plotted data and precision error of gauges, and possible hysteresis at low flow velocity due to experimental procedur

    Risk evaluation for production-injection recompletion and sidetrack

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    Using a decision tree and stochastic parameters, expected monetary value is calculated to evaluate optimal sidetrack time. In view of placing a high confidence level on analytical approach to optimal sidetrack time for a waterflooded reservoir based on possible uncertainty of economic and reservoir parameters and probability of sidetrack success, a major assumption on a parameter in a previous study is re-evaluated. Material balance and displacement efficiency are used to re-evaluate this critical waterflood performance parameter. The change in the relative influence of the stochastic parameters to optimal sidetrack time due to re-evaluation calls for much attention with probable need to further reduce assumptions made, however insignificant the parameter may be. This change will affect the degree of acceptability of the analytical approach. The probability of success of sidetrack sums up the geological and technical uncertainties, deconvolution of these will give the analytical approach an edge

    Effect of aluminum oxide nanoparticles on the rheology and stability of a biopolymer for enhanced oil recovery.

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    Uncommon and untested biopolymers in field pilot studies, but applied in laboratory studies are combined with Al2O3 nanoparticles to form nanocomposites for enhanced oil recovery (EOR) performance evaluation. Core plug samples of the Niger Delta region and Berea sandstone were used as the porous media for EOR experiments. Incremental oil recovery sequel to waterflooding (secondary recovery) was 5–12% and 5–7% for potato starch nanocomposite (PSPNP) and gum Arabic nanocomposite (GCNP) respectively. The biopolymer nanocomposites showed improved viscosity over the biopolymers. Thus, the nanoparticle served as a viscosity modifier on one-hand and stability enhancer on the other. EOR was affected by biopolymer and nanoparticle concentration with the attendant catch-22 situation of permeability impairment. The overall higher incremental recovery of applying PSPNP came by an intermediate potato starch (PSP) flooding between waterflooding and PSNP flooding. Consequently, slugs of biopolymer and biopolymer nanocomposite may be the way forward knowing that the biopolymers studied have surface-active constituents

    PERMEABILITY PREDICTION IN WELLS USING FLOW ZONE INDICATOR (FZI)

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    Estimation of permeability values in uncored wells but logged intervals is a worldwide challenge usually encountered in all reservoirs. Permeability estimation is a major risk task in petroleum engineering, as it is a necessity for reservoir description and performance (fluid flow). Permeability obtained from core measurement is usually limited due to the high cost of getting core samples and toilsome analysis required, scoring only being done for certain good sections and well logs are used for predicting permeability in sections where core permeability are unavailable. This makes core derived permeability cost effective and feasible. For this work, statistical and graphical measurement was considered for estimating permeability. Statistical methods employing regression model and flow zone indicator (FZI) were utilized in esta-blishing a mathematical correlation between core data and well logs using equations obtained from plotted graphs. FZImean values obtained from the log-log plot of RQI against Φz, was used to classify the well into different hydraulic flow units (HFUs). Statistical methods were tested using a sample size of over 960 measured permeability data gotten from five wells in an oil field, located in the Niger Delta region of Nigeria. Results obtained from classifying data into hydraulic flow unit using FZI showed better correlation R2 compared to the regression model

    PREDICTION OF CRUDE OIL VISCOSITY USING FEED-FORWARD BACK-PROPAGATION NEURAL NETWORK (FFBPNN)

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    Crude oil viscosity is an important governing parameter of fluid flow both in the porous media and in pipelines. So, estimating the oil viscosity at various operating conditions with accuracy is of utmost importance to petroleum engineers. Usually, oil viscosity is determined by laboratory measurements at reservoir temperature. However, laboratory experiments are rather expensive and in most cases, the data from such experiments are not reliable. So, petroleum engineers prefer to use published correlations but these correlations are either too simple or too complex and so many of them are region-based not generic. To tackle the above enumerated drawbacks, in this paper, a Feed-Forward Back-Propagation Neural Network (FFBPNN) model has been developed to estimate the crude oil viscosity (μo) of Undersaturated reservoirs in the Niger Delta region of Nigeria. The newly developed FFBPNN model shows good results compared to the existing empirical correlations. The μo FFBPNN model achieved an average absolute relative error of 0.01998 and the correlation coefficient (R2) of 0.999 compared to the existing empirical correlations. From the performance plots for the FFBPNN model and empirical correlations against their experimental values, the FFBPNN model's performance was excellent

    Experimental investigation of hydrodynamic slug mitigation potential of an intermittent absorber

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    The need to handle hydrodynamic slugs in a more efficient way becomes important as oil and gas activities shift deep offshore. This study describes the use of a vessel coupled to the pipeline-riser system upstream of the first stage separator for hydrodynamic slug attenuation. The experiments were carried out in a 2″ pipeline-riser system which comprises of a 40 m long horizontal pipe connected to a 11 m high vertical riser followed by a 3 m horizontal topside section. Air and water were used as experimental fluids. Bifurcation maps and slug attenuation index (SAI) have been used to quantify increase in oil production and the slug attenuation potential of this concept. The device was observed to reduce the pressure fluctuations characterising hydrodynamic slug flow up to 22%. The device also provides additional benefits of stabilising the flow at higher valve opening (choke setting) and lower pressure compared to traditional choking. This in practice translates to increase in oil production. Special case of hydrodynamic slugs which exhibit overchoking induced slugging (OIS) was also observed to be relatively attenuated by the introduction of the absorber

    Case Study of the Impact of Cold and Hot Waterflooding Performance by Simulation and Experiment of High Pour Point Oil Reservoir,, Liaohe Oilfield, North-East China

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    Block Shen-95 has been under cold waterflooding for 17 years. Of particular interest is the low recovery of 11.27% for the North Block due to crude oil cloud point being very close to the reservoir temperature. Formation damage near the wellbore region is controlled at production wells by hot-oiling and low injection rates of non-isothermal waterflooding. Optimizing production necessitated looking at core-scale experiment and reservoir-scale simulation waterflooding performance at different temperatures. The intent also, is basically to condition core-scale flooding observations to properly initialize the numerical model. Based on experiment carried out on core samples, sharp decline in oil displacement efficiency occurred, increase in residual oil saturation and increase in the intensity of formation damage below the cloud point. Reservoir simulation depicted decline in production with decreasing flooding temperature captured specifically by change in viscosity around the wellbore region. Change in flow dynamics due to change in relative permeability was not efficiently captured and formation damage impact on porosity and permeability. Reservoir-scale performance for high pour point oil reservoir can better be understood by considering the effects of formation damage on storativity and transmissibility, and fluid rheology. The irreversible process of wax precipitation may cause permanent damage if further from the wellbore regio

    Gas Viscosity Measurement and Evaluation for High Pressure and High Temperature Gas Reservoirs

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    Gas viscosity is an important fluid property in oil and gas engineering due to its impact on hydrocarbon production and transportation, reservoir recovery, fluid flow, deliverability, and well storage. Existing gas viscosity correlations were derived using measured data at low to moderate pressure and temperatures. No measured gas viscosities at high pressure high temperature (HPHT) using reservoir sample are currently available, and using the extrapolation approach is not reliable. Therefore, this research paper presents laboratory measurement of gas viscosity at HPHT and comparative study of some existing gas viscosity correlations using the measured data. The capillary electromagnetic viscometer was used to measure gas viscosity for pressures between 6,000 psia and 14,000 psia; and temperatures of 270 oF and 370 oF. The comparative study shows that the gas viscosity models commonly used in the industry are not very reliable at HPHT conditions. Ohirhian and Abu (2008) performed better than other evaluated correlations with the mean relative error of -5.22 and absolute error of 8.752 for the temperature of 270oF while Dempsey (1965) came out the best for the temperature of 370oF with mean relative error of -16.88 and 16.88 for absolute mean error. Cross plots showed the poor performance of the evaluated correlations using the measured data at HPHT conditions. From the analysis, the oil and gas industry needs new gas viscosity correlations that can predict gas viscosity at HPHT regio

    THE EFFECT OF REVOLUTION PER MINUTE (RPM) ON IRON OXIDE NANOPARTICLES (Fe3O4NPS) SYNTHESIS THROUGH DIRECT OXIDATIVE ALKALINE HYDROLYSIS

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    Iron oxide nanoparticles are useful particles in many fields such as medical, biomedical and environmental applications. The nature, sizes, purity and composition of these nanoparticles plays important role in their applications especially in biomedical application. This allows for the efficient use of the unique properties of iron oxide nanoparticles for analysis. This paper reports the effect of revolution per minute on the synthesis of iron oxide nanoparticles through oxidative alkaline hydrolysis of iron salt (iron II sulphate). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were used in the analysis of the nanoparticles. The result shows that increase revolution per minute decreases the iron oxide nanoparticles sizes (Fe₃O₄ Nps) with the smallest particle size of 50 nm at 1500 rpm and biggest size of 74 nm for the control sample (without rpm). The nanoparticles from TEM analysis have cubic structure at constant salt concentration of 0.035M. And no significant change in the composition of the nanoparticles synthesized at 200 rpm and the control was observed aside change in their particle size. Nanoparticles synthesized at high revolution per minute of 500 and 1500 rpm showed traces of hematite (α-Fe2O3) and iron oxy hydroxide (γ-FeOOH) as impurities mixed with iron oxide nanoparticles
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