bluuebunny/crossref_metadata_2025 huggingface dataset:
Hybrid Carbonated Low Salinity Waterflood in Calcite-Cemented Sandstone: Effects of Low pH and Salinity on Oil Production and CO2 Storage
Authors: Lee Ji Ho , Hong Eun Ji , Kim Guan Woo , Lee Kun Sang
Published: October 2018

Hybrid carbonated low salinity waterflood (CLSWF) introduces synergetic effects of oil viscosity reduction and wettability modification. The technology injecting CO2-saturated low salinity water is a hybrid design of low salinity waterflood (LSWF) and carbonated waterflood (CWF). Coupled with geochemical reaction and equation of state (EOS) modeling, this study proposes compositional simulation of the CLSWF process. In a comparison to LSWF to quantify the synergetic effects, CLSWF introduces enhanced wettability modification effect due to geochemical reactions of ion-exchange and mineral dissolution. The low pH and salinity conditions during CLSWF dissolve significant calcite mineral to increase Ca2+ molality. It results in more cation-exchange and enhances wettability modification following LSWF mechanism. CO2 is transported from CO2-saturated low salinity water to oil during CLSWF. This interphase transport of CO2 reduces oil viscosity improving mobility ratio. As a result, additional oil production with 6% and improved injectivity are observed in CLSWF. In addition, CLSWF introduces CO2 storage effect. Despite of the interphase transport of CO2, significant CO2 is remained in water and captured in reservoir. Therefore, the novel CLSWF is shown to be a promising technology securing both enhanced oil production and CO2 storage.
High Efficiency Static Mixer Technology for Crude Desalting
Authors: Alhajri Nasser A. , White Ramsey J. , Oshinowo Lanre M.
Published: October 2018

A high-efficiency static mixer was installed at the inlet of a desalter vessel at a Saudi Aramco gas-oil separation plant (GOSP) under an initiative to field trial new technologies to enhance crude quality of low water and salt content, and to optimize wash water consumption used in the desalting. This paper describes a high-efficiency static mixer assessment through Computational Fluid Dynamics (CFD) modeling and an extensive field trial. The technology, which is the first of its kind implemented in Saudi Aramco, is a compact wafer style mixer with a specially designed orifice plate. Enhanced turbulent mixing of wash water with wet crude oil improves desalting efficiency, resulting in lower desalter outlet salt-in-crude concentration and/or reduced wash water consumption. The compact design of the mixer and the restricted lengths of upstream and downstream straight run piping requirements makes this mixer ideal for installation in congested areas without the adequate space for conventional spool static mixers. The high- efficiency static mixer produced a 17% reduction of wash water consumption after installation downstream the conventional mixing valves and upstream the desalter inlet at the Saudi Aramco facility while maintaining the salt-content at 5-6 pounds per thousand barrels of crude oil. A total saving of more than 8½ million gallons of wash water was achieved during the nine month field trial. Further analysis by Saudi Aramco, including CFD modeling, identified the potential to improve mixer performance and gain further reductions in wash water rates by optimizing the mixer location.
Recent Advances in Foamed Acid Fracturing
Authors: Karadkar Prasad , Bataweel Mohammed , Bulekbay Aslan , Alabdrabalnabi Mohammed
Published: October 2018

Foamed acid fracturing is gaining importance in maximizing flowback recovery and is particularly applicable when reservoir energy is not sufficient to effectively flow back the well. Laboratory studies and field implementations during the 1980s showed application of foamed acid in addressing three fundamental issues of acid fracturing such as reactivity control, fluid loss control, and conductivity generation but it was evaluated at low temperature and in shallow wells. Recently, foamed acid has been successfully utilized to energize reservoirs to enhance flowback recovery and restore production after treatment. This paper summarizes literature reports from the last 30 years, showing improved use of foamed acid for acid fracturing.

Foamed acid offers additional benefits such as retardation, deeper conductivity generation, reduced water consumption, and improved acid diversion. Foamed acid laboratory studies from literature such as foam stability, rheology, reaction kinetics, fluid loss, diversion characteristics, and dynamic acid etching is reviewed. Comparison of CO2 and N2 foamed acid is documented in this paper to define fluid selection criteria for a typical foamed acid treatment. Foamed acid rheology at different quality is also summarized in this paper from previous studies.

The dissolution of carbonate rock is controlled by reactivity, which is greatly reduced after foaming for the same acid strength and temperature. Foamed acid having 50-60 quality could retard 60-70% acid reactivity. Excessive fluid loss is one of the challenges in acid fracturing. Conventionally, fluid loss is mitigated by using synthetic polymers to viscosify acid that controls leakoff by depositing a low permeability filter cake on the face of formation leading formation damage concerns. Foamed acid does not build filter cake and showed excellent leakoff control. Proper reactivity and fluid loss control regulates conductivity generation in acid fracturing. Conductivity generation depends on kinetic parameters — such as acid type/strength, temperature, reaction time, and flow regime. These parameters affect the amount of rock removed during the acidizing process. Case histories from different regions where recent application of foamed acid is documented show placement strategies and lessons learned. A horizontal well in one case study was treated with N2 foamed acid to achieve a 2.5 fold increase in production. N2 and CO2 foam was used as foam diverter in acid fracturing, and the productivity index increased to 38% with the use of N2 foam while in other fields the productivity index increased to 3.25 fold with the use of CO2 foam.

Laboratory studies available in the literature are not adequate to design foamed acid treatment for high-temperature, high-pressure wells. This paper summarizes published literature showing improved use of foamed acid for acid fracturing.
Real-Time Monitoring and Evaluation of Actual Vs. Simulated Torque and Drag In Deviated, Long Lateral, Open-Hole Gas Wells
Authors: Hashmi Ahmad Atef , Duran Roberto , Kadura Ahmad , Vega Roberto
Published: October 2018

This paper describes the implementation of a system for evaluating actual torque and drag when running multistage fracturing (MSF) completion equipment in long, open-hole (OH) lateral sections. The process uses an important evaluation tool to compare with results from simulated scenarios, which helps with real-time decision making when actual parameters differ from those simulated.

Torque and drag (T&D) were simulated using different friction coefficients. Actual torque and drag data collected while performing a previous reaming trip were combined with caliper logs to evaluate the running-in-hole (RIH) of the OH MSF completion equipment. Real-time monitoring of the actual run and continuous evaluation provided important information that helped in avoiding sticking, as well as the high-circulating-pressure scenarios that led to loose OH laterals in similar previous wells. Using the evaluation tool significantly increased the success rate of running the OH MSF completion equipment in gas wells.

The torque-and-drag simulations enabled ease of operation when running the OH MSF completion equipment to the target depth. Various techniques are presented that were used in the torque and drag simulations to accurately predict real-time parameters and properly anticipate downhole variables while running in hole. Logging data from a caliper run performed on the OH formation were uploaded into the torque-and-drag software, which enabled a more realistic simulation. This helped to pass through expected tight spots and washouts in the OH. Additionally, the previous reaming trip provided valuable data concerning friction-factor coefficients; a torque-and-drag simulation of the reaming trip was performed, and the differences in parameters while running in hole were monitored. The friction factors were adjusted to match the actual parameters of the reaming trip, and those same friction factors were then used to simulate the OH MSF completion. This technique provided a more suitable reference in terms of expected parameters.

Running OH MSF completion equipment in a long, lateral OH poses significant risks for sticking or decreased circulating capability, particularly in wells drilled in the minimum stress direction. Adding the evaluation process to the existing real-time monitoring system allows for predicting adverse scenarios before they become irreversible; thus, the modeling increases the likelihood of successful system deployment, which, in turn, allows for a quicker turnaround to production.
A Theoretical and Practical Comparison of Capacitance-Resistance Modeling With Application to Mature Fields
Authors: Temizel Cenk , Salehian Mohammad , Cinar Murat , Gok Ihsan Murat , Alklih Mohamad Y.
Published: October 2018

With the advances in data-driven methods, they have become more widely-used in analysis, predictive modeling, control and optimization of several processes. Yet, as it is a relatively new area in petroleum industry with promising features, the industry overall is still skeptical on use of data-driven methods as it is a data-based solution rather than traditional physics-based solutions. In this sense, in order to shed light on the background and applications in this area, this study comparatively evaluates one of the methods used in waterflood surveillance and optimization called capacitance-resistance model illustrated on two types of mature fields with high and low-perm characteristics.

Data-driven methods serve as a robust tool to turn data into knowledge. Historical data generally has not been used in an effective way in analyzing processes due to lack of a well-organized data where there is a huge potential of turning terrabytes of data into knowledge. A capacitance-resistance model is built to identify the well connectivities between the wells and then carry that knowledge to better reservoir management through optimization of injection and production in two different sets of data.

In CRM modeling, analysis of injection/production data at associated injectors and producers reveals the connectivities and further optimization leads to optimum injection values. Steps and the methodology of building a CRM model using real data is illustrated to exemplify the whole process in a comparative way between two mature reservoirs. We introduce the concept of application of spatial constraints in terms of injection-producer maximum influence radius to accelerate and improve the solution where knowledge of radius of influence for an injector is known by historical data and experience.

The theoretical and practical information is supported with mature field examples to investigate the factors affecting the performance of vertical wells in tight and intermediate-permeability reservoirs along with the outline of the major challenges and how to solve them. This study also illustrates the challenges of application of CRM on a tight reservoir in the order of 0.1md and comparison of the application of the method on a more intermediate-perm reservoir. Field data used in this study is from publicly available, open access source, Division of Oil, Gas & Geothermal Resources (DOGGR) website - http://www.conservation.ca.gov/dog
Numerical Simulation Study on the Applicability of Relative Permeability Modifiers for Water-Shutoff in Oil Production Wells
Authors: Alfarge Dheiaa , Wei Mingzhen , Bai Baojun , Almansour Abdullah
Published: October 2018

Disproportionate Permeability Reduction (DPR) is often used as a water-shutoff treatment in production wells when conventional solutions such as mechanical isolations are difficult to perform. Although this property has been well documented by different investigators, the performance of DPR treatments in field applications has varied between success and failure without understandable reasons. This work investigated DPR performance in different scenarios to see when, where and at which conditions DPR treatments can give better results. Numerical simulation methods were used to simulate different scenarios happening in oil and gas fields such as five-spot pattern system and linear-system, with different number of layers, with and without crossflow. The possibility of using DPR treatment in hydraulically-fractured reservoirs was also investigated since many reports indicated that there is an increase in water production after some oil and gas reservoirs being hydraulically-fractured. Moreover, the physical reasoning behind the variations in DPR performance for different scenarios has been extensively discussed.

The results explored that DPR performance was excellent in both of water-cut reduction and oil-recovery improvement when the flow regime was viscous dominated (viscous-gravity number<0.1). On the other hand, when the flow regime was gravity dominated (viscous-gravity number >10), the effective period of DPR treatment was short-term remedy. Secondly, when the high-K layer is existed at the lower-zone of oil or gas reservoir is a good candidate for DPR treatment as compared when the high-K layer located at the upper zone. Furthermore, selecting the correct time to perform DPR treatments generally has a significant role to mitigate water production. Finally, the dimensions of treated fracture are the key components to get a successful DPR-treatment in fractured reservoirs.
Simulation Study of Effects of Surfactant Properties on Surfactant Enhanced Oil Recovery in Fractured Reservoirs
Authors: Cheng Xiaoqian , Kleppe Jon , Torsæter Ole
Published: October 2018

Surfactant addition could improve oil recovery of water flooding in mixed-wet/oil-wet naturally fractured reservoirs by changing wettability or reducing water/oil interfacial tension (IFT). But the mechanisms of surfactant enhanced oil recovery (EOR) in fractured reseroirs are not fully understood. One objective of this work is to analyze the effects of surfactant properties (viscosity, concentration, and adsorption) on surfactant EOR at laboratory scale. The other objective is to obtain the functional relationships between surfactant properties and oil recovery of surfactant flooding.

A core with length of 8 cm and diameter of 4 cm is cut into two parts from the middle to imitate the matrix with a horizontal fracture whose space is 0.1 cm. The middle slide with a width of 0.1 cm is used as the model in this study. Fluid is injected from left side of the fractured and produced from the right side. The original properties of matrix, brine, and oil are from Ekofisk Field. The properties of surfactant are assumed based on literatures. Eclipse is used as the simulator.

The viscosity of surfactant solution has no obvious effect on ultimate oil recovery. But the time to obtain ultimate oil recovery, which is called the ultimate oil recovery time in this paper, is linearly increasing with the increase of viscosity. Since most of surfactants have no significant effect on viscosity of brine, the viscosity of surfactant solution is not a key parameter of surfactant screening for surfactant EOR in fractured reservoirs. The increase of surfactant concentration results in a decrease of oil recovery rate, and an increase of ultimate oil recovery. The ultimate oil recovery at 364 days of surfactant flooding has a negative linear relationship with inverse square root of surfactant concentration. The surfactant concentration has a more significant effect on oil recovery from lower matrix than the oil recovery from upper matrix. The ratio (RC) of the maximum mass of adsorbed surfactant to the mass of surfactant at critical micelle concentration (CMC) is used to describe the effect of surfactant adsorption on oil recovery. Two cases are studied and results imply that the surfactant capability of wettability alteration should be considered first for surfactant screening. If surfactants have the same capability of wettability alteration, then the surfactant adsorption is a key parameter, and the smaller surfactant adsorption concentration leads to a larger ultimate oil recovery.

This work helps to understand the mechanism of surfactant flooding in fractured reservoirs, and could be used as a reference for surfactant screening for surfactant EOR in fractured reservoirs. The functional relationships between surfactant properties and oil recovery help to improve upscaling methods.
Performance and Economic Analysis of a Novel Heavy Oil Recovery Process Using In-Situ Steam and Nitrogen Generated by Thermochemicals
Authors: Moussa Tamer , Patil Shirish , Mahmoud Mohamed
Published: October 2018

Heavy oil has attracted global attention due to its huge volume of original oil in place. However, there are numerous operation and economic challenges to the recovery of heavy oil due to its high-viscosity and high-density. Thermal recovery methods such as steam injection is viable and commonly used to recover heavy oil and bitumen primarily by viscosity reduction of heavy oil and improving the displacement of the heavy oil. However, there are significant heat losses before the steam reaches the heavy-oil reservoir, in addition to the concerns of high cost and emission of greenhouse gases. One of the promising new heavy-oil recovery approaches is generating steam with nitrogen gas, in-situ, using thermochemical reaction to reduce oil viscosity, improve the mobility ratio and enhance the heavy-oil displacement. Steam and nitrogen are generated, in-situ, by injecting exothermic reactants downhole with the injected water to create heat and enhance reservoir pressure for mobilizing heavy oil. The exothermic reaction is triggered by either increasing downhole temperature or in the presence of a low pH weak acid.

In this research, a numerical study of the novel heavy oil recovery process using in-situ steam and nitrogen generated by thermochemical reactions in field scale is conducted. Various ratios of nitrogen- steam are studied to identify their effect on the recovery efficiency. In-situ Nitrogen-steam ratio generated by thermochemical is optimized to accomplish the maximum achievable net present value (NPV) after ten years of recovery. The CMG STARS simulator is used to simulate reservoir models with different operational parameters.

The results show that the generated heat from in-situ thermochemical reactions was sufficient to reduce the viscosity of heavy oil, while the generated nitrogen gas provided a good heat insulation effect and reduced steam-oil ratio. Thus, higher NPV was achieved than typical conventional steam-only injection method.

This is the first time NPV and all economic parameters are considered to analyze the performance of an in-situ steam and nitrogen generated by thermochemical reaction. This research shows that the recovery of the proposed method is more suitable and economical for the reservoirs which are not viable for conventional steam flooding methods and it is a step forward to eliminate CO2 emissions associated with thermal recovery process.
High GOR MPFM Flow Loop Testing Evaluation and Pre-Qualification
Authors: Faraj Ali , Benlizidia Imed
Published: October 2018

Multiphase flow metering has become one of the main well testing and reservoir production monitoring for many oil operators. The technological advances in instrumentation and flow modelling has been lately able to address the challenging application in measuring the flow rates of high gas-oil-ratio (GOR) and high gas volume fraction (GVF) with an acceptable accuracy and reliability.

The objective of this paper is to discuss and evaluate the results of a pre-qualification test of three Multiphase Flow Meter (MPFM) technologies conducted in various third party flow loop test facilities mimicking high GOR field conditions. It will also clearly set the procedures and methodologies used to verify the field performance and viability to install those MPFM technologies in a high GOR environment.

Oil fields producing under high GOR flow conditions (more than 90% GVF) pose a technical challenge for in-line MPFM to provide accurate and reliable flow rate measurements. The testing of those technologies in the filed in such harsh environment requires a great deal of planning and careful design and monitoring of the reference measurement that imposes a major time and cost impacts. For this reason, a pre-qualification test of potential MPFM technologies for high GOR environment was conducted in a third party flow loop facility utilizing live hydrocarbons under simulated field operational conditions. These technologies are based on Venturi in association with additional measuring principles to cope with the high GOR conditions including nuclear fractioning, tomography, gamma-ray densitometer and multi-dimensional and multi- frequency electric permittivity measurement system.

This pre-qualification flow loop test was designed to ensure that clear conclusions are reached and that a purely objective evaluation of the results can be performed. Evaluating these MPFM technologies in well controlled and contained flow low loop has enabled a solid assessment of the metrological performance under high GOR. A coherence GVF mapping of each MPFM technology was formulated to help in the assessment in selecting the appropriate technology for the field application.
Technical Feasibility of Concentrated Solar Parabolic Trough Heating for Thermal-Based Desalination Process With Application in Produced Oilfield Water
Authors: Velarde Ruvalcaba , Alejandro Salvador
Published: October 2018

In wet-crude handling facilities, a desalting system requires wash water to reduce salt content of crude before shipping it to a stabilization plant. Produced water could be treated and used as wash water instead of consuming groundwater resources. Due to the high produced water salinity, this treatment could be done via thermal desalination method, such as humidification-dehumidification (HDH) distillation process.

One heat source available for thermal desalination is solar energy. Concentrated solar parabolic trough technology uses a heat transfer fluid to absorbe solar energy resource and provide heat to process fluids via a heat exchanger. The technology can be applied to heat produced water to the desired temperature at the HDH inlet. In this study, the technical feasibility of using concentrated solar parabolic trough heating for HDH process with application in produced oilfield water in Saudi Arabia is conducted. Concentrated solar parabolic trough performance is modelled and simulated via a public released renewable energy software. Also, technical considerations for process potential application are elaborated upon.

The results presented show the capability and overall scheme blocks in which concentrated solar parabolic trough contributes towards achieving heat requirements to HDH desalination process.

The approach studied in this paper tackles both energy and water conservation. It provides an overview on the use of alternative energy source for heat transfer fluid in an oilfield produced water desalination process with the potential to displace diesel or associated gas consumption. At the same time, the produced water treatment process displaces groundwater consumption.
Research on Interfacial Rheology of Chemical Flooding Systems
Authors: Tie Leilei , Yu Meng , Zheng Yufei , Li Xiang , Zhang Bo , Liu Wenhui , Xue Xinfang , Zhang Zhonggang
Published: October 2018

There are various interface phenomena in the process of foam flooding, so the interfacial rheological technique has a broad application prospect in the field of foam flooding. We can obtain the micro process information of interface through the study of interfacial rheological properties, which contributes to obtain a better explanation of the mechanism of foam generation, foam stability, and the effect of foam flooding. In this paper, the interfacial dilational rheological technology was used to investigate surface rheological properties of foam flooding systems. At the same time, the relationship between interfacial rheology and foam flooding recovery was also studied. To study the relationship between foam performance and surface parameters, sodium dodecyl sulfate (SDS)/long chain alcohol systems and long chain alkyl three methyl ammonium chloride systems were investigated.

Results show that due to different matchings of long chain alcohol molecules and SDS molecules, foaming volume and foam half-life of SDS solution increase at first then decrease with addition of lauryl alcohol, myristyl alcohol, cetyl alcohol and stearyl alcohol. Results show very slight variations in surface tension, while dilational modulus, elastic modulus, and surface viscosity of the systems increase at first then decrease. With the growth of hydrophobic chain, foaming volume and foam half-life of LTAC, TTAC, CTAC and OTAC decrease in turn, surface tension shows subtle changes, dilational modulus and elastic modulus decrease in turn. However, we obtain relatively low value for the viscous modulus of all the four long chain alkyl three methyl ammonium chloride systems. Foaming ability of foam flooding systems is controlled by surface viscoelasticity. Stability of foam flooding systems is mainly affected by surface rheological properties, and there is significant linear relationship between foam half-life and elastic modulus. Combining with the displacement experiment, a greater interfacial dilational elasticity results in a higher oil recovery. The conclusion is consistent with results of injection pressure in the macro core-flooding experiment and the change of sweep efficiency in the microscopic displacement experiment.

The results will provide insights in understanding the mechanism of foam flooding from the point of interfacial rheology.
Superheated Steam-Air Coupled With Toe-Point Injection Technique for Heavy Oil EOR: A Numerical Study on Horizontal Wellbore Mass and Heat Transfer Characteristics
Authors: Feng Naichao , Cheng Shiqing , Yu Haiyang , Shi Wenyang , Qin Jiazheng , Zhang Jia , Sun Fengrui , Du Changhao , Liu Xin
Published: October 2018

In this paper, a novel model is proposed to characterize superheated steam-air (SSA) pressure and temperature distribution in horizontal wells with toe-point injection technique. Firstly, the mathematical model of SSA flow in both tubing and annulus is established based on the mass, momentum and energy conservation equations, and it is solved by employing finite difference method. The mass and heat transfer are coupled with injection of SSA into formation and heat exchange between tubing and annulus by iterative technique. Then, the proposed model is validated by field data. Finally, the effect of mass fraction of air and injection temperature on SSA temperature, pressure, mass flow rate in annulus and heat transfer rate from annulus fluid to formation are conducted.

Results indicate that: (1). The SSA temperature in tubing decreases while flowing from heel point to toe point and the temperature gradient decreases with distance to heel point. (2). The SSA temperature in annulus first decreases and then turns to increase while flowing from toe point to heel point. (3). The SSA pressure in tubing decreases linearly from heel point to toe point, while the SSA pressure gradient in annulus decreases with the distance to toe point. (4). The SSA temperature in both tubing and annulus decreases with the increasing of mass fraction of air. This is because the enthalpy of air is smaller than superheated steam. (5). Increasing injection temperature can decrease the SSA pressure in both tubing and annulus by reducing SSA density and increasing frictional loss.

Based on the presented model, the SSA pressure and temperature in both tubing and annulus can be accurately predicted with the relative error less than 5%. The theoretical studies in this paper can be taken as a reference for engineers in optimization of injection parameters and provide following researchers with the very basic theory for the application of toe-point injection technique.
The Effect of Salt-Laden Degraded MEG on Gas Hydrate Inhibition
Authors: Alef Khalid , Barifcani Ahmed
Published: October 2018

The formation of gas hydrates in pipelines continues to be a major challenge in gas production. Conventionally, thermodynamic hydrate inhibitors (THIs) are used to inhibit hydrate formation. Mono- ethylene glycol (MEG) is commonly utilized as a hydrate inhibitor due to its recoverability. However, during the recovery process, MEG may undergo multiple phases of thermal exposure which may lead to the degradation of MEG. In this study, MEG solution with realistic brine composition was tested for its gas hydrate inhibition performance.

The typical lean-MEG solution was prepared by combining pure MEG in a brine solution based on common formation water salt composition. The degraded samples were extracted from a MEG recovery pilot plant that had undergone a complete recovery operation (~13 h). Samples were then taken for gas hydrate testing using a high-pressure PVT cell. The isobaric hydrate testing method was employed for accurate hydrate equilibria results.

The new hydrate equilibria data revealed a hydrate promotion effect amongst the degraded MEG samples as opposed to pure non-degraded MEG. Although salt in the MEG solution improved hydrate inhibition, the results show that the inhibition effect was decreased as the extent of MEG degradation increased. Furthermore, MEG degradation products were identified to be acetic, formic, and glycolic acid. Observations reveal a color change from colorless to slightly yellow depending on the extent of thermal degradation of the MEG samples.
Design of a Pipeline Pre-Activation Inspection Robot for Pipeline Tap Detection
Authors: Idachaba Francis Enejo
Published: October 2018

Crude oil pipeline vandals have been known to insert taps on new pipelines as they are being laid or when the pipelines are inactive. These insertions in the pipelines also known as taps allow the vandals to steal and continue to steal crude oil from the pipeline as long as it is pumped through the line. This approach is difficult to detect using the available leak detection technologies as the crude is not leaked into the environment and does not cause a sudden reduction in the pipeline pressure. The Pre-activation Inspection robot is a battery powered self-actuated robot deployed into the lines to inspect the pipeline and provide a video feedback of the pipeline internal surface before crude oil is pumped. This robot can be deployed as the last stage of the handover process to ensure that the lines are free of taps before the pipeline is activated. It will enable operators determine if their lines have been tapped and also enable the localization of such taps. This deployment is capable of minimizing the volume of crude oil theft from pipelines and also providing information on the state of the pipeline internal surface.
A Realistic Kick Simulator for Casing Design - Part 2: Well Design and Execution
Authors: Chukwudi Ohaegbulam , Stanley Ibeh , Boniface Obah , Stanley Onwukwe
Published: October 2018

This paper is a continuation of SPE paper 189167 (A realistic kick simulator for casing design-part 1). A transient kick simulator that is based on kick tolerance concept using the drillers’ method was developed for well design. The purpose of this work is to demonstrate how the formulated model was used in well design. Supplementary models was developed to assist the drilling engineer to make the right decisions in the events of uncertainty and well control incidents during drilling thereby minimizing downtime. During well design, the casing seat points must be placed at a competent formation that must be able to withstand the hydrostatic pressure exerts by the drilling mud column as well as the kick imposed pressure and frictional pressures that will arise during the secondary well control operations. As the drilling operation is moving to more challenging fields (tight windows between pore and fracture pressure, HPHT wells, depleted fields, deep water wells) the importance of incorporating kick tolerance in the well design programme cannot be overemphasized. Hence, a realistic optimization of casing seat points using the proposed kick model and pore-fracture pressure gradients was implemented in this work. The casing seat point is a function of a pre-design kick volume, kick intensity, and the well geometry. A method to estimate the internal burst load for surface and intermediate casing using the proposed model with a design kick volume (limited kick) and kick intensity was demonstrated in this work. These methods were compared with the conventional methods and their advantages/disadvantages were analyzed. Results show that the use of kick simulator/incorporation of kick tolerance in well design programme translate to cost reduction and increased safety over conventional methods.
Pressure Transient Behavior of Horizontal Wells in Naturally Fractured Reservoirs with Formation Sensitive Properties
Authors: Emeli Hilary U. , Igbokoyi Alpheus O.
Published: October 2018

Production of fluids from petroleum reservoirs reduces the pore pressure, increases the net overburden stress, and consequently, reduces the total porosity and permeability of the reservoir rock. This effect is much more significant in low permeability geo-pressured and naturally fractured reservoirs. For well test purpose, the assumption of constant permeability in the diffusivity equation will yield inaccurate estimates of the reservoir properties for any reservoirs in geo-pressured zone. To study the pressure transient behavior in a stress dependent porous media, it is assumed that permeability of the formation is stress dependent. Hence, a new parameter known as the permeability modulus is introduced.

In this study, the effect of stress-sensitivity was incorporated by expressing the permeability as an exponential function of pore pressure in the derivation of a three-dimensional diffusivity equation required to describe the flow of fluid for a horizontal well in a naturally fractured reservoir. The matrix-fracture fluid transfer model considered was the pseudo-steady state flow model. Since pragmatic values for the dimensionless permeability modulus ranges between zero and unity, it was possible to apply the theory of perturbation to develop and solve a system of linear boundary value problem subject to an infinite lateral and bounded vertical boundary condition. Applying the Laplace and finite Fourier cosine transform, an approximate analytical solution in Laplace space was obtained which was inverted numerically. Pressure response curves were generated and analyzed for certain vital parameters.
Improving Hole Cleaning Efficiency using Nanosilica in Water-Based Drilling Mud
Authors: Gbadamosi Afeez O. , Junin Radzuan , Oseh Jeffrey O. , Agi Augustine , Yekeen Nurudeen , Abdalla Yassir , Ogiriki Shadrach O. , Yusuff Adeyinka S.
Published: October 2018

Inadequate wellbore cleaning contributes to several major drilling problems such as; increase in torque and drag that can limit the reach to target, mechanical pipe sticking, difficulties in casing and cementing and logging operations that can increase well cost significantly. Meanwhile, effective removal of drilled cuttings from the wellbore improves penetration rate and drilling efficiency. Herein, water-based mud was formulated with nanosilica to enhance cuttings and solid particles transport from the wellbore to the surface. Four different weight percent concentrations of nanosilica (0.001, 0.003, 0.005 and 0.01 wt.%) at three different flow rates in litres/seconds (0.4, 0.6 and 1.0) and cutting size (small, medium and large) were used to investigate the formulated water-based mud lifting capacity of the drilled cuttings and other solid particles. Thereafter, the hole cleaning efficiency of the water-based mud containing nanosilica was compared to conventional water-based mud. The results show that nanosilica water-based mud influences the cuttings lifting capacity. The addition of the nanosilica concentrations to the water-based mud enhances the viscosity, thereby increasing the muds carrying and circulating capacity. Moreover, nanosilica water-based mud displays mud stability that will stabilize the wellbore and prevent the intrusion of formation fluids into it when compared with the conventinal water-based mud. The effect of cuttings size on the wellbore cleaning is minimal. The large cuttings size shows a lower degree of cuttings transportation compared with the small and medium cutting size. The small cuttings size has higher cuttings recovery to the surface. Finally, though increase in flowrate leads to more cuttings recovery, there is every tendency that much fluid flow rate will cause an increase in frictional pressure losses and equivalent circulating density, high pump pressure requirement and potential hole erosion.
Structured Benchmarking Approach for High Complexity Wells: A Case Study of Bonga Wells
Authors: Ezenwanne Elesie O. , Giadom Bari-Dumene
Published: October 2018

The approach to determining the proper benchmark dataset for checking the competitiveness of high complexity wells should involve a systematic definition of the well complexity variables that have a direct impact on the performance of the well.

What makes a well complex and how their competitiveness can be measured against similar wells is a thing of debate. Ranking wells on a universal scale of complexity is itself difficult and controversial as there are several factors that define how complex a well is.

Traditional methods of benchmarking assess the competitiveness of a drilling operation by plotting the performance variable against an independent variable (typically drilled interval). But drilled interval is only one element of complexity.

A few literatures have defined well complexity in terms of the ratio of measured depth to true vertical depth. Other literatures have also recognized factors that impact well complexity such as the type of well profile, kick-off point, long and highly inclined tangent sections, horizontal displacement, water depth, pressure gradients etc. A combination of these factors has been identified to lead to increased complexities in a well. Thus, the ability to measure the competitiveness of extended reach wells has become increasingly difficult.

This paper has been divided into two sections to explore several techniques for defining well complexity and address the challenge with finding the right benchmark dataset to assess the competitiveness of complex wells. Based on the outcome of the analysis, a structured classification of well complexities will be generated for input to benchmarking categorization for high complexity wells. This will thus, enable the prediction of the future performance of wells with higher complexities than conventional wells.
Viability of SiO2 Nanoparticles for Enhanced Oil Recovery in the Niger Delta: A Comparative Analysis
Authors: Ajulibe Daniel , Ogolo Naomi , Ikiensikimama Sunday
Published: October 2018

Based on the consistent laboratory success of SiO2 and its compatibility with sandstone reservoirs, it has been widely recommended for enhanced oil recovery (EOR). However, the economics must be commensurate with acceptable returns on investment given the current market realities. This study was focused on determining the economic advantage of SiO2 Nano-Fluid flooding for enhanced oil recovery in the Niger Delta as a tool for quality investment decision.

To achieve this, a comparative economic analysis was performed by evaluating economic feasibility of Alkaline Surfactant Polymer (ASP) Flooding, Water Alternating Gas (WAG) and SiO2 Nano-Fluid Flooding using a discounted net cash flow model for the Niger Delta and the recovery factors for the compared alternatives obtained from core-flood experiments. Economic indicators including Net Present Value (NPV), Internal Rate of Return (IRR), Profitability Index (PI) and Discounted Payback Period were used in ranking the alternative recovery methods based on their performance; and sensitivity analysis on some model inputs performed to observe their effect on the NPV of investment returns.

From the results obtained, SiO2 Nano-Fluid Flooding had an NPV of $57.88M with a payback period of 2 years. A profitability index of 1.83 and an internal rate of return of 75% with a hurdle rate of 15% was also observed for this option. ASP and WAG had NPVs of $15.45M and $25.3M respectively, with an internal rate of return above the hurdle rate. The results indicated that while all 3 compared alternatives are profitable for the Niger Delta, SiO2 Nano-Fluid flooding is potentially the most profitable. The consideration of this result and a subsequent implementation would be of advantage to oil producing companies in the Niger-Delta and provide a basis for the local manufacture of SiO2 Nano-particles.
Empirical Correlation for Estimation of the Vapourized Oil-Gas Ratio for Gas-Condensate Systems
Authors: Molokwu V. C. , Makinde O. M. , Onyekonwu M. O.
Published: October 2018

The increasing interest in production from liquid-rich reservoirs calls for an efficient method for estimating its fluid properties and more importantly, from production data. The gas material balance for liquid rich systems is largely dependent on several PVT parameters. One of such parameters is the vapourized oil-gas ratio, which defines the amount of stock tank condensate that drops from one standard cubic feet of produced well stream gas. The vapourized oil-gas ratio is usually obtained by Extended Black Oil simulation using an Equation of State (EOS) model well tuned to the PVT experimental data. This experimental data might not be readily available when needed for a quick analysis and even when available, the process of tuning requires great skill and experience of the reservoir engineer. An empirical correlation for the vapourized oil-gas ration is proposed based on a statistical evaluation of values obtained from several simulations (Extended Black Oil) using a tuned Equation of State Model. 14 representative gas-condensate samples from the Niger Delta were used to generate over 2000 lines of vapourized oil-gas ratio. The developed correlation have input parameters, which are readily obtained from field production data. This approach is easily applicable, and valid for a wide range of gas-condensate compositions. It predicts, to a good extent, the vapourized oil-gas ratio for a pressure depletion sequence without recourse to a rigorous EOS modelling.
The New-Dawn for Liquefied Natural Gas Utilization: Empowering the Transportation Sector in Nigeria
Authors: Nwosi Hezekiah Andrew , Appah Dulu , Kinigoma Boma
Published: October 2018

It is a recurrent decimal that conventional transportation fuel is becoming a scarce commodity in Nigeria. Owing to Oil refineries producing below designed capacity and not meeting with demand for transportation fuel in the country. This has been investigated to result from weak maintenance culture, technical issues and increase in population etc. The result has led to several man-hour losses, overdependence on foreign imported refined products and many more not to mention. Presently, production network processes via the transportation sector has been hindered due to the paucity sustainability of fuel supply. Auspiciously, Nigeria holds an abundant of Natural Gas deposits of 187tcf proven reserves which is underutilized in several sectors, especially the transportation sector which accommodate about 75% of the total energy usage in the country. Hence, the idea of using LNG as a transportation fuel is well-thought-out. This paper looks at the thermodynamic effect and computational fluid considerations involved in applying the LNG as a transportation fuel to attain longer distance travel. A numerical simulation was conducted using Finite Element Analysis (FEA) to determine the pressure distribution of the cryogenic tanks as well as the thermal effect of atmospheric disturbances through computational fluid dynamics. The result of atmospheric temperature is measured to be 25°C and as a result inlet velocity is set at 183.2 K. The LNG temperature initialized at −155, while the tank pressure equals 1.2bar. The tank heating and the heat flux is simulated for 5 hours per day km. Initial volume of LNG cryogenic storage tank is 60 liters, initial LNG temperature of 162°c, heat leakage per hour each day were measured to be 1.3 W and 1 bar, respectively. Initial mass flow rates of LNG Boil-off gas production (kg) 1%, 1.2%, 1.4%, 1.6% and 1.8%. Atmospheric Heat (KJ/h) and Mass Flow Rate the results are 0%, 0%, 0.000187% 0.000551% and 0.0009262% respectively. LNG can be used to transport vehicles to a very long distance of 1300Km without re-fill. Finally, the likelihood of utilizing LNG as a transportation fuel will be of immense economic and environmental benefit over Gasoline, diesel and CNG to the midstream sector.
Application of Competitive Scoping in Data Acquisition Plan Using Value of Information VOI
Authors: Awasthi Amit , Joshua Itua , Das Anindya
Published: October 2018

The cost of acquiring formation evaluation data is responsible for a significant portion of well costs. In the volatile oil price world, the well data acquisition programs have come under severe scrutiny to ensure adequate value is generated from every dollar spent. To support the process, generic Value of Information (VOI) analysis modules were developed to help justify data acquisition. Critical to the correct use of the modules is a good understanding of the key uncertainties, relevant business/operations decisions and associated data required to reduce uncertainties. The application of the modules on a typical shallow-water development well resulted in circa 20% cost reduction. Furthermore, this workflow has the potential to be replicated on a bigger scale (i.e. on more wells) in a bid to reduce field development costs.
Investigating the Potential Use of Waste Vegetable Oils to Produce Synthetic Base Fluids for Drilling Mud Formulation
Authors: Dankwa O. K. , Ackumey S. S. , Amorin R.
Published: October 2018

The environmental challenges posed by conventional oil-based drilling fluids along with legislation associated with their use have necessitated the development of synthetic organic liquids that are designed to improve environmental protection. In this research, waste/used oils from restaurants and food joints have been tested for their potential use as synthetic based fluids through rheological analysis. Physiochemical properties of the waste vegetable oil were determined; density: 0.88g/cm3, acid value: 64.8mg KOH/g of oil and Free Fatty Acid (FFA) content: 32.4%. The optimum conditioning of biodiesel production from waste oil was in two-step catalysed process. In the first step, sulfuric acid was used as a catalyst for esterification reaction to reduce acid value of the oil below 3mg KOH/g which was with different dosages. The next step was the base catalysed transesterification process which converted the pre-treated oil into biodiesel and glycerol in the presence of methanol and NaOH at varied reaction conditions. Density of 9.1 lb/gal and rheological properties; Yield Point (17 Ib/100ft2, 2 Ib/100ft2 and 2 Ib/100ft2), Plastic Viscosity (17cP, 8cP and 6cP), Gel strength at 10Ȳ (3 Ib/100ft2, 2 Ib/100ft2 and 2 Ib/100ft2) and Gel strength at 10″ (5 Ib/100ft2, 4 Ib/100ft2 and 2 Ib/100ft2) were all determined at temperatures of 80°F, 120°F and 160°F respectively. The formulated mud showed that biodiesel is a promising synthetic based fluid and has most of its rheological properties meeting the API standard. Though the initial cost of conditioning biodiesel will be quite high, it can be offset by its disposal cost as compared to that of diesel.