Toe-To-Heel Waterflooding. Part ll: 3D Laboratory-Test Results

2006 ◽  
Vol 9 (03) ◽  
pp. 202-208 ◽  
Author(s):  
Alexandru T. Turta ◽  
Ashok K. Singhal ◽  
Jon Goldman ◽  
Litong Zhao
Keyword(s):  
Oil Recovery ◽  
3D Model ◽  
Water Saturation ◽  
Mobility Ratio ◽  
Laboratory Model ◽  
Oil Viscosity ◽  
Vertical Wells ◽  
Sweep Efficiency ◽  
Gravity Segregation ◽  
Laboratory Test Results

Summary A new waterflooding process, toe-to-heel waterflooding (TTHW), was developed, based partly on a recently developed thermal TTH displacement process, TTH air injection (THAI). TTHW is a novel oil-recovery process that uses a horizontal producer (HP) and a vertical injector (VI). The HP has its horizontal leg located at the top of formation, while its toe is close to the VI, which is perforated at the lower part of the formation. TTHW realizes a gravity-stable displacement, in which the water/oil mobility ratio becomes less important and its detrimental effect on sweep efficiency is diminished; the injected water always breaks through at the toe, after which water cut gradually increases. A systematic investigation of the TTHW process in a Hele-Shaw laboratory model mimicking a simulated porous medium showed that the process substantially improved the vertical sweep efficiency as compared to conventional waterflooding. Following these semiquantitative tests, a more comprehensive 3D-model testing was undertaken to investigate the overall sweep efficiency of the process. The 3D model consists of a metal box filled with glass beads and saturated with oil at connate-water saturation. Oil was displaced with high-salinity brine, either in a TTH configuration or in a conventional array, using only vertical wells. A staggered line drive was used by injecting water in two vertical wells located at one side of the box and producing oil by using either an HP with its toe close to the injection line or a vertical producer located at the HP's heel position. Several TTHW tests were carried out at different injection rates. For a given injection rate, the TTHW results were compared to those of conventional-waterflooding tests. For the same amount of water injected, the ultimate oil recovery increased by a factor of up to 2, as compared to that for conventional waterflooding. All in all, the results of these investigations show that the novel TTHW process is sound and can be optimized further. Introduction Conventional waterfloods in heavy-gravity-oil reservoirs (oil viscosity higher than 100 mPa.s) are limited by three main factors:• Reservoir heterogeneity, leading to water channelling.• Gravity segregation (caused by oil/water density contrast), leading to underriding of the injected water.• Highly unfavorable water/oil mobility ratio, which aggravates the adverse effects of the first two factors. Usually, the heterogeneity is caused by pronounced vertical stratification, manifested by a relatively large contrast in the horizontal permeability of different layers. On the other hand, the negative effect of gravity segregation is felt mainly when the stratification is not very pronounced and effective vertical permeability of the pay zone is relatively high. The effect of gravity segregation on waterflood performance was reported in 1953 when the first mathematical model of water tonguing (underriding) was published by Dietz (1953). Initially, Dietz's theory was believed to be applicable mostly to thick formations. However, subsequently, Outmans showed that this theory was equally applicable to thin oil formations (Sandrea and Nielsen 1974).

Unit Mobility Ratio Displacement Calculations for Pattern Floods in Homogeneous Medium

1966 ◽  
Vol 6 (03) ◽  
pp. 217-227 ◽  
Author(s):  
Hubert J. Morel-Seytoux
Keyword(s):  
Oil Recovery ◽  
Numerical Solutions ◽  
Mobility Ratio ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Numerical Techniques ◽  
Sweep Efficiency ◽  
Closed Form Solutions ◽  
Regular Patterns ◽  
Quantities Of Interest

Abstract The influence of pattern geometry on assisted oil recovery for a particular displacement mechanism is the object of investigation in this paper. The displacement is assumed to be of unit mobility ratio and piston-like. Fluids are assumed incompressible and gravity and capillary effects are neglected. With these assumptions it is possible to calculate by analytical methods the quantities of interest to the reservoir engineer for a great variety of patterns. Specifically, this paper presentsvery briefly, the methods and mathematical derivations required to obtain the results of engineering concern, andtypical results in the form of graphs or formulae that can be used readily without prior study of the methods. Results of this work provide checks for solutions obtained from programmed numerical techniques. They also reveal the effect of pattern geometry and, even though the assumptions of piston-like displacement and of unit mobility ratio are restrictive, they can nevertheless be used for rather crude but quick, cheap estimates. These estimates can be refined to account for non-unit mobility ratio and two-phase flow by correlating analytical results in the case M=1 and the numerical results for non-Piston, non-unit mobility ratio displacements. In an earlier paper1 it was also shown that from the knowledge of closed form solutions for unit mobility ratio, quantities called "scale factors" could be readily calculated, increasing considerably the flexibility of the numerical techniques. Many new closed form solutions are given in this paper. INTRODUCTION BACKGROUND Pattern geometry is a major factor in making water-flood recovery predictions. For this reason many numerical schemes have been devised to predict oil recovery in either regular patterns or arbitrary configurations. The numerical solutions, based on the method of finite difference approximation, are subject to errors often difficult to evaluate. An estimate of the error is possible by comparison with exact solutions. To provide a variety of checks on numerical solutions, a thorough study of the unit mobility ratio displacement process was undertaken. To calculate quantities of interest to the reservoir engineer (oil recovery, sweep efficiency, etc.), it is necessary to first know the pressure distribution in the pattern. Then analytical procedures are used to calculate, in order of increasing difficulty: injectivity, breakthrough areal sweep efficiency, normalized oil recovery and water-oil ratio as a function of normalized PV injected. BACKGROUND Pattern geometry is a major factor in making water-flood recovery predictions. For this reason many numerical schemes have been devised to predict oil recovery in either regular patterns or arbitrary configurations. The numerical solutions, based on the method of finite difference approximation, are subject to errors often difficult to evaluate. An estimate of the error is possible by comparison with exact solutions. To provide a variety of checks on numerical solutions, a thorough study of the unit mobility ratio displacement process was undertaken. To calculate quantities of interest to the reservoir engineer (oil recovery, sweep efficiency, etc.), it is necessary to first know the pressure distribution in the pattern. Then analytical procedures are used to calculate, in order of increasing difficulty: injectivity, breakthrough areal sweep efficiency, normalized oil recovery and water-oil ratio as a function of normalized PV injected.

An Easy Calculation Method on Sweep Efficiency of Chemical Flooding

2013 ◽  
Vol 275-277 ◽  
pp. 496-501
Author(s):  
Fu Qing Yuan ◽  
Zhen Quan Li
Keyword(s):  
Oil Recovery ◽  
Orthogonal Design ◽  
Polymer Flooding ◽  
Water Flooding ◽  
Solution Viscosity ◽  
Chemical Flooding ◽  
Oil Viscosity ◽  
Sweep Efficiency ◽  
Easy Calculation ◽  
Polymer Compound

According to the geological parameters of Shengli Oilfield, sweep efficiency of chemical flooding was analyzed according to injection volume, injection-production parameters of polymer flooding or surfactant-polymer compound flooding. The orthogonal design method was employed to select the important factors influencing on expanding sweep efficiency by chemical flooding. Numerical simulation method was utilized to analyze oil recovery and sweep efficiency of different flooding methods, such as water flooding, polymer flooding and surfactant-polymer compound flooding. Finally, two easy calculation models were established to calculate the expanding degree of sweep efficiency by polymer flooding or SP compound flooding than water flooding. The models were presented as the relationships between geological parameters, such as effective thickness, oil viscosity, porosity and permeability, and fluid parameters, such as polymer-solution viscosity and oil-water interfacial tension. The precision of the two models was high enough to predict sweep efficiency of polymer flooding or SP compound flooding.

scholarly journals Enhanced Oil Recovery: Chemical Flooding

2021 ◽  
Author(s):  
Ahmed Ragab ◽  
Eman M. Mansour
Keyword(s):  
Interfacial Tension ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Recovery Phase ◽  
Mobility Ratio ◽  
Chemical Flooding ◽  
Sweep Efficiency ◽  
Oil Displacement ◽  
Remaining Oil ◽  
Oil Displacement Efficiency

The enhanced oil recovery phase of oil reservoirs production usually comes after the water/gas injection (secondary recovery) phase. The main objective of EOR application is to mobilize the remaining oil through enhancing the oil displacement and volumetric sweep efficiency. The oil displacement efficiency enhances by reducing the oil viscosity and/or by reducing the interfacial tension, while the volumetric sweep efficiency improves by developing a favorable mobility ratio between the displacing fluid and the remaining oil. It is important to identify remaining oil and the production mechanisms that are necessary to improve oil recovery prior to implementing an EOR phase. Chemical enhanced oil recovery is one of the major EOR methods that reduces the residual oil saturation by lowering water-oil interfacial tension (surfactant/alkaline) and increases the volumetric sweep efficiency by reducing the water-oil mobility ratio (polymer). In this chapter, the basic mechanisms of different chemical methods have been discussed including the interactions of different chemicals with the reservoir rocks and fluids. In addition, an up-to-date status of chemical flooding at the laboratory scale, pilot projects and field applications have been reported.

The Experimental Analysis of the Role of Flue Gas Injection for Horizontal Well Steam Flooding

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Zhanxi Pang ◽  
Peng Qi ◽  
Fengyi Zhang ◽  
Taotao Ge ◽  
Huiqing Liu
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
Flue Gas ◽  
Three Dimensional ◽  
Steam Injection ◽  
Displacement Efficiency ◽  
Oil Viscosity ◽  
Sweep Efficiency ◽  
Steam Flooding ◽  
Heavy Oil Reservoirs

Heavy oil is an important hydrocarbon resource that plays a great role in petroleum supply for the world. Co-injection of steam and flue gas can be used to develop deep heavy oil reservoirs. In this paper, a series of gas dissolution experiments were implemented to analyze the properties variation of heavy oil. Then, sand-pack flooding experiments were carried out to optimize injection temperature and injection volume of this mixture. Finally, three-dimensional (3D) flooding experiments were completed to analyze the sweep efficiency and the oil recovery factor of flue gas + steam flooding. The role in enhanced oil recovery (EOR) mechanisms was summarized according to the experimental results. The results show that the dissolution of flue gas in heavy oil can largely reduce oil viscosity and its displacement efficiency is obviously higher than conventional steam injection. Flue gas gradually gathers at the top to displace remaining oil and to decrease heat loss of the reservoir top. The ultimate recovery is 49.49% that is 7.95% higher than steam flooding.

An Investigation Into Propagation Behavior of the Steam Chamber During Expanding-Solvent SAGP (ES-SAGP)

SPE Journal ◽  
2019 ◽  
Vol 24 (02) ◽  
pp. 413-430
Author(s):  
Zhanxi Pang ◽  
Lei Wang ◽  
Zhengbin Wu ◽  
Xue Wang
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
Physical Simulation ◽  
Heat Losses ◽  
Oil Reservoirs ◽  
Oil Viscosity ◽  
Sweep Efficiency ◽  
Experimental Conditions ◽  
Steam Chamber ◽  
Heavy Oil Reservoirs

Summary Steam-assisted gravity drainage (SAGD) and steam and gas push (SAGP) are used commercially to recover bitumen from oil sands, but for thin heavy-oil reservoirs, the recovery is lower because of larger heat losses through caprock and poorer oil mobility under reservoir conditions. A new enhanced-oil-recovery (EOR) method, expanding-solvent SAGP (ES-SAGP), is introduced to develop thin heavy-oil reservoirs. In ES-SAGP, noncondensate gas and vaporizable solvent are injected with steam into the steam chamber during SAGD. We used a 3D physical simulation scale to research the effectiveness of ES-SAGP and to analyze the propagation mechanisms of the steam chamber during ES-SAGP. Under the same experimental conditions, we conducted a contrast analysis between SAGP and ES-SAGP to study the expanding characteristics of the steam chamber, the sweep efficiency of the steam chamber, and the ultimate oil recovery. The experimental results show that the steam chamber gradually becomes an ellipse shape during SAGP. However, during ES-SAGP, noncondensate gas and a vaporizable solvent gather at the reservoir top to decrease heat losses, and oil viscosity near the condensate layer of the steam chamber is largely decreased by hot steam and by solvent, making the boundary of the steam chamber vertical and gradually a similar, rectangular shape. As in SAGD, during ES-SAGP, the expansion mechanism of the steam chamber can be divided into three stages: the ascent stage, the horizontal-expansion stage, and the descent stage. In the ascent stage, the time needed is shorter during ES-SAGP than during SAGP. However, the other two stages take more time during nitrogen, solvent, and steam injection to enlarge the cross-sectional area of the bottom of the steam chamber. For the conditions in our experiments, when the instantaneous oil/steam ratio is lower than 0.1, the corresponding oil recovery is 51.11%, which is 7.04% higher than in SAGP. Therefore, during ES-SAGP, not only is the volume of the steam chamber sharply enlarged, but the sweep efficiency and the ultimate oil recovery are also remarkably improved.

Fitting Foam-Simulation-Model Parameters to Data: II. Surfactant-Alternating-Gas Foam Applications

2014 ◽  
Vol 18 (02) ◽  
pp. 273-283 ◽  
Author(s):  
W. R. Rossen ◽  
C. S. Boeije
Keyword(s):  
Steady State ◽  
Capillary Pressure ◽  
Oil Recovery ◽  
Water Saturation ◽  
Field Application ◽  
Model Parameters ◽  
Fractional Flow ◽  
Sweep Efficiency ◽  
Water Fraction ◽  
Foam Model

Summary Foam improves sweep in miscible and immiscible gas-injection enhanced-oil-recovery processes. Surfactant-alternating-gas (SAG) foam processes offer many advantages over coinjection of foam for both operational and sweep-efficiency reasons. The success of a foam SAG process depends on foam behavior at very low injected-water fraction (high foam quality). This means that fitting data to a typical scan of foam behavior as a function of foam quality can miss conditions essential to the success of an SAG process. The result can be inaccurate scaleup of results to field application. We illustrate how to fit foam-model parameters to steady-state foam data for application to injection of a gas slug in an SAG foam process. Dynamic SAG corefloods can be unreliable for several reasons. These include failure to reach local steady state (because of slow foam generation), the increased effect of dispersion at the core scale, and the capillary end effect. For current foam models, the behavior of foam in SAG depends on three parameters: the mobility of full-strength foam, the capillary pressure or water saturation at which foam collapses, and the parameter governing the abruptness of this collapse. We illustrate the fitting of these model parameters to coreflood data, and the challenges that can arise in the fitting process, with the published foam data of Persoff et al. (1991) and Ma et al. (2013). For illustration, we use the foam model in the widely used STARS (Cheng et al. 2000) simulator. Accurate water-saturation data are essential to making a reliable fit to the data. Model fits to a given experiment may result in inaccurate extrapolation to mobility at the wellbore and, therefore, inaccurate predicted injectivity: for instance, a model fit in which foam does not collapse even at extremely large capillary pressure at the wellbore. We show how the insights of fractional-flow theory can guide the model-fitting process and give quick estimates of foam-propagation rate, mobility, and injectivity at the field scale.

Nanofluid Precoating: An Effective Method To Reduce Fines Migration in Radial Systems Saturated With Two Mobile Immiscible Fluids

SPE Journal ◽  
2018 ◽  
Vol 23 (03) ◽  
pp. 998-1018 ◽  
Author(s):  
Bin Yuan ◽  
Rouzbeh Ghanbarnezhad Moghanloo
Keyword(s):  
Oil Recovery ◽  
Analytic Solution ◽  
Numerical Solutions ◽  
Fine Particles ◽  
Water Saturation ◽  
Splitting Method ◽  
Immiscible Fluids ◽  
Mechanistic Modeling ◽  
Sweep Efficiency ◽  
Fines Migration

Summary Prediction of how nanofluid applications can potentially control fines migration in porous media saturated with two immiscible fluids requires a mechanistic modeling approach. We develop analytic solutions to evaluate the efficiency of nanofluid utilization to reduce fines migration in systems saturated with two immiscible fluids. In this study, fines migration in the radial-flow system saturated with two immiscible fluids (oil and water) is considered; two capture mechanisms of fine particles—fines attachment and straining—are incorporated into the modeling work. The analytic solution is derived by implementing the splitting method and stream-function transformation to convert a 2 × 2 (nonhomogeneous) system of equations into an equation with a fine-particle component (nanoparticle effects) and a lifting equation in which only water saturation appears. Through quantitative comparison of suspended fines and water-saturation-profile plots, the accuracy of the analytic solution is verified with finite-difference numerical solutions. Saturation c-shock and saturation s-shock appear in the analytical solutions. The fines migration and consequent phenomena (fines attachment, fines straining, and fines suspension) decelerate the breakthrough of the injected fluids (better sweep efficiency) and increase the corresponding front saturation of the injected fluid near the wellbore—i.e., larger relative permeability (better injectivity). The results suggest that fines attachment onto the grain surface and well injectivity are enhanced after nanofluid pretreatment; moreover, the smallest radius to be pretreated by nanofluid is approximated to maintain its benefits. In practice, our analytic approach provides a valuable mathematical structure to evaluate how nanoparticle usage can enhance performance of water-based enhanced-oil-recovery (EOR) techniques in reservoirs with a fines-migration issue.

scholarly journals Estimation of Oil Recovery Factor for Water Drive Sandy Reservoirs through Applications of Artificial Intelligence

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3671 ◽  
Author(s):  
Ahmed Mahmoud ◽  
Salaheldin Elkatatny ◽  
Weiqing Chen ◽  
Abdulazeez Abdulraheem
Keyword(s):  
Artificial Intelligence ◽  
Oil Recovery ◽  
Water Saturation ◽  
Data Availability ◽  
Recovery Factor ◽  
Coefficient Of Determination ◽  
Support Vector ◽  
Subtractive Clustering ◽  
Oil Viscosity ◽  
Inference System

Hydrocarbon reserve evaluation is the major concern for all oil and gas operating companies. Nowadays, the estimation of oil recovery factor (RF) could be achieved through several techniques. The accuracy of these techniques depends on data availability, which is strongly dependent on the reservoir age. In this study, 10 parameters accessible in the early reservoir life are considered for RF estimation using four artificial intelligence (AI) techniques. These parameters are the net pay (effective reservoir thickness), stock-tank oil initially in place, original reservoir pressure, asset area (reservoir area), porosity, Lorenz coefficient, effective permeability, API gravity, oil viscosity, and initial water saturation. The AI techniques used are the artificial neural networks (ANNs), radial basis neuron networks, adaptive neuro-fuzzy inference system with subtractive clustering, and support vector machines. AI models were trained using data collected from 130 water drive sandstone reservoirs; then, an empirical correlation for RF estimation was developed based on the trained ANN model’s weights and biases. Data collected from another 38 reservoirs were used to test the predictability of the suggested AI models and the ANNs-based correlation; then, performance of the ANNs-based correlation was compared with three of the currently available empirical equations for RF estimation. The developed ANNs-based equation outperformed the available equations in terms of all the measures of error evaluation considered in this study, and also has the highest coefficient of determination of 0.94 compared to only 0.55 obtained from Gulstad correlation, which is one of the most accurate correlations currently available.

scholarly journals CO2 Foam and CO2 Polymer Enhanced Foam for Heavy Oil Recovery and CO2 Storage

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5735
Author(s):  
Ali Telmadarreie ◽  
Japan J Trivedi
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
Co2 Storage ◽  
High Mobility ◽  
Pressure Profile ◽  
Gas Production ◽  
Heavy Oil Recovery ◽  
Oil Viscosity ◽  
Sweep Efficiency ◽  
Co2 Foam

Enhanced oil recovery (EOR) from heavy oil reservoirs is challenging. High oil viscosity, high mobility ratio, inadequate sweep, and reservoir heterogeneity adds more challenges and severe difficulties during any EOR method. Foam injection showed potential as an EOR method for challenging and heterogeneous reservoirs containing light oil. However, the foams and especially polymer enhanced foams (PEF) for heavy oil recovery have been less studied. This study aims to evaluate the performance of CO2 foam and CO2 PEF for heavy oil recovery and CO2 storage by analyzing flow through porous media pressure profile, oil recovery, and CO2 gas production. Foam bulk stability tests showed higher stability of PEF compared to that of surfactant-based foam both in the absence and presence of heavy crude oil. The addition of polymer to surfactant-based foam significantly improved its dynamic stability during foam flow experiments. CO2 PEF propagated faster with higher apparent viscosity and resulted in more oil recovery compared to that of CO2 foam injection. The visual observation of glass column demonstrated stable frontal displacement and higher sweep efficiency of PEF compared to that of conventional foam. In the fractured rock sample, additional heavy oil recovery was obtained by liquid diversion into the matrix area rather than gas diversion. Aside from oil production, the higher stability of PEF resulted in more gas storage compared to conventional foam. This study shows that CO2 PEF could significantly improve heavy oil recovery and CO2 storage.

Thermally Active Polymer To Improve Sweep Efficiency of Waterfloods: Simulation and Pilot Design Approaches

2012 ◽  
Vol 15 (01) ◽  
pp. 86-97 ◽  
Author(s):  
R.. Garmeh ◽  
M.. Izadi ◽  
M.. Salehi ◽  
J.L.. L. Romero ◽  
C.P.. P. Thomas ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Pilot Project ◽  
Oil Reservoirs ◽  
Reservoir Rock ◽  
Sensitivity Analyses ◽  
Chemical Components ◽  
Chemical Adsorption ◽  
Oil Viscosity ◽  
Sweep Efficiency ◽  
Thief Zone

Summary A common problem in many waterflooded oil reservoirs is early water breakthrough with high water cut through highly conductive thief zones. Thermally active polymer (TAP), which is an expandable submicron particulate of low viscosity, has been successfully used as an in-depth conformance to improve sweep efficiency of waterfloods. This paper describes the workflow to evaluate technical feasibility of this conformance technology for proper pilot-project designs supported with detailed simulation studies. Two simulation approaches have been developed to model properties of this polymer and its interaction with reservoir rock. Both methods include temperature-triggered viscosification and adsorption/retention effects. Temperature profile in the reservoir is modeled by energy balance to accurately place this polymer at the optimum location in the thief zone. The first method considers a single chemical component in the water phase. The second method is based on chemical reactions of multiple chemical components. Both simulation approaches are compared and discussed. Results show that temperature-triggered polymers can increase oil recovery by viscosification and chemical adsorption/retention, which reduces thief-zone permeability and diverts flow into unswept zones. Sensitivity analyses suggest that ultimate oil recovery and conformance control depend on the thief-zone temperature, vertical-to the horizontal-permeability ratio (Kv/Kh), thief-zone vertical location, injection concentration and slug size, oil viscosity, and chemical adsorption and its reversibility, among other factors. For high-flow-capacity thief zones and mobility ratios higher than 10, oil recoveries can be improved by increasing chemical concentration or slug size of treatments, or both. Reservoirs with low Kv/Kh (< 0.1) and high permeability contrast generally shows faster incremental recoveries than reservoirs with high Kv/Kh and strong water segregation. The presented workflow is currently used to perform in-depth conformance treatment designs in onshore and offshore fields and can be used as a reference tool to evaluate benefits of the TAP in waterflooded oil reservoirs.

Sign in / Sign up

Export Citation Format

Share Document