bluuebunny/crossref_metadata_2025 huggingface dataset:
Soft Computation Application to Optimize Drilling Bit Selection Utilizing Virtual Inteligence and Genetic Algorithms
Authors: Jamshidi Emad , Mostafavi Hossein
Published: May 2016

Drilling industry encounters various challenges during planning and drilling a new well. There are numerous parameters related to drilling operations that are planned and adjusted as drilling advances. Among them, bit selection is one of the most influential considerations for planning and constructing a new borehole.

Conventional bit selections are mostly based on drillers' experiences in the field or mathematical equations which stand more on recorded performances of similar bits from offset wells. It is evident that these sophisticated interrelations between parameters never can be stated in a single mathematical equation. In such intricate cases, utilizing virtual intelligence and Artificial Neural Networks (ANNs) is proven to be worthwhile in understanding complex relationships between variables.

In this paper, two models are developed with high competence and utilizing ANNs. The first model provides appropriate drilling bit selection based on desired ROP to be obtained by applying specific drilling parameters. The second model uses proper drilling parameters obtained from optimizing procedure to select drilling bit which provides maximum achievable ROP. Meanwhile, Genetic Algorithm (GA), as a class of optimizing methods for complex functions, is applied. The proposed methods assess the current conditions of drilling system to optimize the effectiveness of drilling, while reducing the probability of early wear of the drill bit. The correlation coefficients for predicted bit types and optimum drilling parameters in testing the obtained networks are 0.95 and 0.90, respectively.

The proposed methodology opens new opportunities for real-time and in-field drilling optimization that can be efficiently implemented within the span of the existing drilling practice.
A Novel Emulsified Acid System for Stimulation of Very High-Temperature Carbonate Reservoirs
Authors: Pandya Nisha , Wadekar Sushant
Published: May 2016

Because the world demand for energy is expected to continue growing, exploration is turning to deeper and high-temperature reservoirs. Such reservoirs include fields with high bottom hole static temperatures (BHSTs), such as the Ursa (250°F) and Thunder Horse (280°F) in Gulf of Mexico (GOM). Acid stimulation of such reservoirs at high temperature is a challenging task. Emulsified acid systems are expected to perform better in reservoirs with BHSTs ranging from 275 to 375°F compared to nonretarded acids and gelled acid systems. However, fluid stability and the inhibition of corrosion are major challenges to overcome for successful implementation of this technology. Emulsion instability and the corrosion rate are interrelated, and both increase with higher temperature. Also, fluid stability decreases as a result of corrosion of the metal surfaces. At the same time, an excessive addition of corrosion inhibitor destabilizes the fluid system. Hence, the proper selection and balance between the corrosion inhibitor and emulsifiers are required. Three different types of corrosion inhibitors were evaluated, and an emulsified system was designed with proper optimization of various ingredients, including corrosion inhibitor, an intensifier, and a cationic emulsifier. The system was tested for stability and corrosion loss with static corrosion test using P-110 coupons. After reviewing the literature, it is believed that this emulsified system is the only one to pass static corrosion tests at 275°F for 4 hr and remain stable at 300°F for 2 hr with 28% acid strength. This enables the acid stimulation of carbonate reservoirs having BHSTs up to 300°F while reducing the corrosion rate. As per the study, the effect of the intensifier was different to that found in plain acid, suggesting possible interactions of the additives with the emulsifier. Because fluid stability and the rate of corrosion are interrelated, they should be evaluated together, especially for designing emulsified acid systems for stimulation of very high-temperature carbonate reservoirs.
Fracture Finite Difference Seismic Modelling
Authors: Ferla Maurizio , D'Agosto Claudio
Published: May 2016

The objective of this study is to measure the seismic response of fluid filled fractures, trying to evaluate which acquisition survey parameters can better highlight this feature. The scope of fracture modelling is simulating the presence of a fracture system in the area of interest verifying if it is detectable and describable by a 3D P-wave or PS-wave seismic data, for issues related to operative aspects but also for future support to the drilling activity.

A system of aligned fractures can be described as an effective anisotropic medium when the dominant wavelength is long compared to the fracture scales. In order to model the behavior of seismic waves in fractured media, we can characterize the model with normal and tangential crack compliances, Coates and Schoenberg (1995). The main measurable effects on seismic data are the shear wave splitting and p-wave AVOaz anomalies. Shear-wave splitting due to the alignment of vertical cracks can be recognized by the polarization of the fast split shear-wave, which is usually parallel to the local strike of cracks and can be used to characterize fracture orientation. The time delay between fast and slow shear-waves is closely related to the intensity of crack-inducedanisotropy in the medium (proportional to the fracture density).

The main question to answer is if a 3D multicomponent survey can detect the travel time shift between parallel and perpendicular directions generated by the investigated formation. The second subject is to investigate the potentiality of fluid discrimination with PS waves but also PP waves. Modeled data is generated using elastic anisotropic finite difference code. The analogies between cracks systems and anisotropic media have been analyzed in order to infer interesting considerations about fractures characterization. The anisotropic parameters and the geophysical model have been assumed on the basis of in place data measurements.

The obtained results demonstrated the correlation between the seismic features and the fracture characteristics, such as crack density, fractures orientation, fluid content and AVO anomalies.
Modeling of Spent-Acid Blockage Damage in Stimulated Gas Wells
Authors: Zhang Q. , Zhu D. , Hill A.D.
Published: May 2016

Aqueous fluids introduced by different stimulation treatments cause water blockage in the near-wellbore region of wells. This water blockage acts the same as formation damage when the well is put back on production. One of the examples is when gas wells in carbonate reservoirs are acid-stimulated; the wormholes that propagate into the formations might be surrounded by a region of high water saturation created by the leak off of spent acid. The spent-acid blockage damage could be severe, especially in lower permeability regions where capillary forces are relatively high. This paper presents a model that investigates the spent-acid damage in wormhole region of acid-stimulated gas wells.

The phenomenon of spent-acid blockage was first investigated in the experimental study to identify the problem. A lab-scaled model was then developed to characterize the capillary pressure and relative permeability behavior by matching the results from the model to the experimental observation. We then extended the study to field-scale by approximating the wormhole as a long, slender half-ellipsoid centered in an ellipsoidal flow field. The simulations that focused on the displacement regime of spent acid recovery process were developed. These models were solved numerically to predict pressure behavior and spent acid distributions for the flow-back process.

With the models, we studied the effects of several key factors, such as capillary pressure, relative permeability, and addition of additives, on the efficiency of spent acid recovery. The results show that common additives routinely added to acid systems may aid, or hinder, spent acid recovery, depending primarily on their effects on rock wettability. With the studies performed on the model developed, we provide recommendations for minimizing spent acid damage to gas well productivity.
Anisotropic Waveform Inversion with Well Constraints
Authors: Wang Chao , Yingst David , Leveille Jacques , Bloor Robert
Published: May 2016

The term, "Waveform inversion" (WFI), refers to a collection of techniques that use the information from seismic data to derive high-fidelity earth models for seismic imaging. The attractiveness of WFI lies mainly in its lack of approximations, at least in a theoretical sense, in contrast to other model determination techniques such as semblance or tomography. However, a whole raft of approximations must be made to make the technique viable with today'scomputing technology and restrictions of seismic acquisition. These are collectively referred to as "waveform inversion strategies" and in this paper we mainly discuss regularization and preconditioning strategies. Because the wavefields need to be accurately modeled to represent the kinematics of all the waves during WFI iterations, the effects of anisotropy often help to improve WFI results. In this paper, forward modeling and its adjoint computation are based on acoustic wave equations in vertical transversely isotropic (VTI)media. We introduce a multi-parameter inversion for P-wave velocity and anisotropy parameters. WFI is a highly nonlinear, ill-posed problem. We introduce additional information and turn the unconstrained optimization problem into a constrained optimization problem in order to reduce the ill-posedness. The geophysics of the problem leads to appropriate constraints, such as restriction of model parameters, or information from well logs. In this paper, we use well logs as constraints and solve the problem using the augmented Lagrangian method (ALM), a mathematical method that replaces a constrained optimization problem by a series of unconstrained problems. The ALM with well constraints aims at preserving velocity characteristics from welllogs and providing us with more reliable velocity updates. This paper presents the acoustic anisotropic WFI implementation using ALM with well constraints. It also discusses practical strategies for regularization and preconditioning and their influences on the models that are obtained from WFI. We illustrate these approaches on a 2D synthetic Marmousi example and another application to 3D VSOOBC data from the Green Canyon area of the Gulf of Mexico. From the results, we show that multi-parameter VTI WFI with ALM provides us with more useful and reliable model updates. To further evaluate our WFI results, we also compare offset gathers and RTM images and illustrate their significant improvement susing updated models generated from WFI.
Utilizing Distributed Temperature Sensor Data in Predicting Flow Rates in Multilateral Wells
Authors: Almulla J.M. , Yang C. , Zhu D.
Published: May 2016

The new advancements in well monitoring tools have increased the amount of data that could be retrieved with great accuracy. The new challenge that we are facing today is to maximize the benefits of the large amount of data provided by these tools. One of these benefits is to utilize the continuous stream of data to determine the flow rate in real time of a multilateral well. Temperature and pressure changes are harder to predict in horizontal laterals compared with vertical wells because of the lack of variation in elevation and geothermal gradient. Thus the need of accurate and high precision gauges becomes critical. A theoretical model is developed to predict temperature and pressure in trilateral wells. The model is used as a forward engine in the study and an inversion procedure is then added to interpret the data to flow profiles. The forward model starts from a specified reservoir with a defined well structure. Pressure, temperature and flow rate in the well system are calculated in the mother bore (main hole) and in the laterals. Then we use the inverse model to interpret the flow rate profiles from the temperature and pressure data measured by the downhole sensors. A gradient-based inversion algorithm is used in this work, which is fast and applicable for real-time monitoring of production performance. In the inverse model, the flow profile is calculated until the one that matches the temperature and pressure in the well is identified. The production distribution from each lateral is determined based on this approach.

Examples are presented in the paper. The value of the model approach for production optimization for trilateral wells is illustrated through parametric study.
Integrated Reservoir Management Utilising a Portfolio Approach to Beat the Impact of Delayed Water Injection Projects - Opportunistic Strategic Alignment in North Kuwait
Authors: Chetri H.B. , Al-Ajmi Hussain
Published: May 2016

North Kuwait is blessed with multiple reservoirs stacked, Tuba at the shallowest and Ratawi at the deepest level. Water flood expansion was the key ingredient to provide the short term production assurance for the Asset. Field development activities have been progressing for two of the major stacked reservoirs withlion's share of incremental production (Mauddud & Upper Burgan), assuming that these reservoirs will get the benefit of water injection, to cope up with the enhanced level of production. Unfortunately, the water injection projects have been delayed till the end of 2013, leading to rapid decline in reservoir pressures and erosion in the well performance of the producers (naturally flowing as well as on artificial lift).

A comprehensive review of the portfolio of all reservoirs was made vis-à-vis the drilling/work over activities. Complete history of pressure-production data for last 40years was analyzed using OFM. The output from the reservoir simulation models was analyzed & discussed with multi-disciplinary teams. Aggressive surveillance & data integration plan was made and implemented to identify the focus areas, from where "new" production can be accelerated and / or controlled, adhering to the best reservoir management practice. Isochronal reservoir pressure maps were updated with full fieldstatic bottom hole pressure surveys. Detailed analysis of the RFT/ PLT data was performed to optimize the perforations at layers with high reservoir pressure. New wells from shallower reservoirs were deepened to the reservoirs enjoying the active water drive and accordingly, completed for short term production till the water injection expansion project is commissioned. Integrated reservoir management approach was followed throughout the gamut of field development activities with multi-skill expertize reviewing as peers for smart decisions.

The paper's objective is to share the integrated Reservoir management approach to beat the impact of delayed water injection projects on overall production portfolio, without compromising the technical requirement of voidage replacement ratio for depletion drive reservoirs with best practices approach.
Application of Low Pressure System at Balingian, Sarawak Brownfield; Candidate Selection and BY Field Case Study
Authors: Ismail M Syahezat , Hamza Norashikin
Published: May 2016

Bayan (BY) is a brown field located in Sarawak region with over 25 years of production. Declining trend in field production resulting from rapidly declining reservoir pressure and increasing water production has prompted aggressive production enhancement activities to arrest further decline. Conventional gas lift method has been widely applied across the field and has provided reliable means of artificial lift to sustain production. However, wells with very low reservoir pressure were not able to sustain production even with gas lift due to the back pressure experienced in the production system.

Low Pressure System (LPS) were implemented in two (2) out of four (4) drilling platforms in BY to sustain and increase the field production, reactivate idle wells and to manage the back pressure for the whole production system. Experience gathered from this implementation enable us to improve the candidate selection process and to share potential limitation imposed by the LPS system to operation.

Actual BY LPS performance is shown here to illustrate the proven success in increasing the field production and unlocking some of BY reserves. The change in the production trend of well's producing in current production system and after being tied to LPS will show the total achieved production gain which in BY case amounted to more than 1.5 million barrels in 4 years of operation.
Fundamental Approaches to Dolomitisation and Carbonate Diagenesis in Different Hydrogeological Systems and the Impact on Reservoir Quality Distribution
Authors: Xiao Yitian , Jones Gareth D. , Whitaker Fiona  F. , B Al-Helal Anwar , Stafford Sherry , Gomez-Rivas Enrique , Guidry Sean
Published: May 2016

The accurate prediction of the geometry of subsurface dolomite geobodies, their connectivity, and the distribution of reservoir properties is a fundamental challenge in carbonate reservoir characterization. Reactive Transport Models (RTM) couple geochemical reactions with fluid flow to facilitate both 2D and 3D quantitative, process-based investigations of dolomitization and related carbonate diagenetic reactions. The paper will highlight new results and key conclusions from simulations of dolomitization mechanisms in four different hydro-geological systems:Brine reflux,Mixing zone and sub mixing zone,Geothermal circulation andFault controlled hydrothermal circulation.

Simulations provide new insights on the spatial distribution and dynamic behavior of:Geometry and distribution of dolomite bodies generated by different styles of subsurface fluid flow and their dynamic interactions;Regional versus local controls on dolomite occurrence and connectivity;Sensitivity and hierarchy of geological controlling parameters;Spatial and temporal relationships between dolomitization and associated diagenetic minerals including anhydrite cements and Mississippi Valley Type(MVT) mineralization;Effect of hydrothermal fluid induced dolomite recrystallization and anhydrite dissolution;Criteria to help identify the distribution of reservoir quality including high permeability dolomite "sweet spots".

When integrated with conventional subsurface data and stratigraphic, geochemical, and structural framework, Reactive Transport Models of dolomitization provide fundamental and robust predictive concepts and reservoir quality models for exploration and new / mature field developments. In particular, the state-of-the-art simulations allow the analysis and 3Dvisualization of dolomite body spatial and temporal evolution that can translate into alternative "process-based" well correlation methods and strategies for populating diagenetic bodies and their petrophysical properties in geological models for reservoir flow simulations.
Successful Implementation of Fiber-Laden Fluid for Hydraulic Fracturing of Jurassic Formations in Western Siberia
Authors: Kayumov Rifat , Borisenko Alexey , Levanyuk Olesya , Savelyeva Irina , Emelyanov Sergey
Published: May 2016

The Urnenskoe field is located in the Tyumen region, Western Siberia. The main production target is the J1 formation belonging to the upper Jurassic Vasyugansk suite. Subsurface geology of the Urnenskoe field features the lithological heterogeneity of the J1 formation with high- and low-permeability interlayers and considerable petroleum reserves in upper low-permeability formation intervals. Oil and water have highly different viscosities permitting rapid water breakthrough into the formation.

The first hydraulic fracturing operations were carried out at the Urnenskoe field in 2010. Because there are rich oil saturated zones in the low-permeability upper zone of the reservoir, the properties of the fracturing fluid to transport proppant and its ability to prevent settling during both the pumping and when the fracture is closing are decisive for the well productivity after the fracturing operation. Fracturing fluid with degradable fibers was selected to achieve these properties during hydraulic fracturing. The fibers create a reinforcing net within the fracturing fluid with proppant and mechanically assist the transportation and suspension of the proppant grains. The temperature decomposes the fibers when the fracture is closed. In addition, the fibers allow lowering the polymer concentration in the fracturing fluid, thus enabling control of the fracture vertical growth and decreasing proppant pack damage.

Since there are no all-season roads and it is difficult to approach the Urnenskoe field in the summer, there was no fracturing fleet capable of performing an operation utilizing the fluid with degradable fibers in July 2011. Therefore, 7 conventional fracturing operations were performed; these can be used to compare the effectiveness of conventional fracturing with another 23 operations in which the fibers were used. These operations revealed that the wells in which the fibers were used had a dimensionless productivity index that was 33% higher, and this effect remained stable. Also, for the wells with the fiber application, the average cumulative oil production for 5 months was 2,245tons higher (recalculated for one well). These results confirm the effectiveness of hydraulic fracturing with degradable fibers in the Urnenskoe field. The successful experience of using hydraulic fracturing with degradable fibers at the Urnenskoe field, laboratory tests of the fiber-laden fluid, analysis of well productivity, and particular applications of the technology provide information to guide further optimization. In addition, the technology has been applied in the Jurassic formations of the neighboring Ust-Tegusskoe field, where a considerable productivity gain was achieved compared with the conventional fracturing operations.
Dual Function Reverse Demulsifier and Demulsifier for the Improvement of Polymer Flooding Produced Water Treatment
Authors: Wu Di , Meng Xiangchun , Zhao Fengling , Lin Sen , Jiang Neng , Zhang Shaohui , Qiao Liyan , Song Hui
Published: May 2016

Adding partially hydrolyzed polyacrylamide (HPAM) to flood water for enhanced oil recovery has resulted in some difficulties for treatment and re-injection of produced water at Daqing Oilfield of China: Production of the injected HPAM increased water phase viscosity and emulsification of the produced fluid, leading to more oil carry-over; The state-of-art cationic water clarifiers showed poor compatibility with HPAM containing produced water due to formation of very sticky oily flocs which seriously pollutes bed filters and slop oil recovered in produced water treatment. Throughputs of existent produced water treatment facilities had to be lowered by up to 50% so that the HPAM containing produced water might be treated to re-injection specifications. As an alternative for the state-of-art cationic water clarifier, a nonionic reverse demulsifier and demulsifier consisting of both water soluble and oil soluble active components respectively for water clarification and water-in-oil emulsion breaking, was developed as a water dispersible micro-emulsion mixture. Injected into high water-cut o/w produced fluid prior to the initial oil/water separation, the dual function chemical greatly enhanced flocculation and coalescence of the oil droplets in the reverse crude oil emulsion while maintaining adequate emulsion breaking capability for downstream crude oil dehydration, leading to less oil carry-over and looser emulsion in the influent water of produced water treatment facilities. In one field application, injected at a dosage of 15mg/L into the polymer flooding produced reverse crude oil emulsion upstream of oil/water separation, the dual function chemical reduced the oil content in the influent water of a produced water treatment facility from 2004mg/L to 443mg/L, and lowered the oil content in the effluent water of bed filters from 31mg/L to 4.1mg/L without application of water clarifiers.
Classification and Evaluation of Ultra-Low Permeability Reservoirs in the Changqing Oilfield
Authors: Ran Xinquan , Li Anqi , Zhao Jiyong , Li Shuheng
Published: May 2016

With the rapid development of the world economy, the exploration and development of unconventional oil and gas resources have become a new hot spot. As an important subset of unconventional reservoirs, ultra-low permeability(ULP) reservoirs have been greatly concerned. Studies suggest that the ultra-low permeability reservoir belongs to the typical tight reservoir. The current low-permeability reservoir classification criteria available in the literature cannot meet the actual needs of ultra-low permeability reservoir development. Through researches, reservoir characterization parameters of effective porosity, mainstream throat radius, movable fluid saturation and starting pressure gradient are screened out to build quaternary classification coefficient. A new standard of classification and evaluation of ultra-low permeability reservoirs is established, and ultra-low permeability reservoirs are divided into three categories. Thus it provides a theoretical basis for speeding up the effective development of ultra-low permeability reservoirs.

Since the beginning of the 21st century, the world economy has entered a new cycle of development. The demand for oil and gas resources in the countries soared. Facing the huge demand for energy, productivity construction and production rate are relatively insufficient throughout the world. Unconventional oil and gas resources are beginning to receive more attention. Ultra-low permeability reservoirs, as important unconventional oil and gas reservoirs, have huge potential for exploration and development, but the current classification of reservoir evaluation criteria cannot meet the needs of ultra-low permeability reservoir exploration and development. In order to effectively guide the exploration and development practice of ultra-low permeability reservoirs, it is of great significance to launch researches on ultra-low permeability reservoir characterization parameter system, and to establish a new classification and evaluation criteria.
Accelerated Career Development for Upstream Digital Professionals Using Performance-Based Training
Authors: Lau Kenneth K. , Abdulkhaaliq Nashid
Published: May 2016

Saudi Aramco has established the Upstream Professional Development Center(UPDC) to train its geoscientists and engineers to independently and proficiently conduct a wide range of exploration and production operations and its systems analysts in providing a collaborative environment for executing these operations. Its purpose is not to replace academic institutions but rather to complement them by introducing activity and performance-based training (PBT) programs. The objective is not only to improve theorganization's overall performance level but to raise the standards of its entire workforce as well.

This paper describes how UPDC's Upstream Computing job family designs, develops and delivers its courses for recently hired Upstream digital professionals(computer scientists and software engineers). It outlines how to effectively train them to acquire a fundamental understanding of a wide range of oil and gas exploration and production (Upstream) operations and to use this knowledge to support, maintain and develop an equally wide range of software applications used for facilitating everyday Upstream operations.

Saudi Aramco's systems analysts are loaned by their line organizations to UPDC to design and implement these courses based on their work experiences and best practices. To teach and/or re-enforce technical concepts, and for employees to gain appreciation of these practices, over 50% of class time is devoted to activities, assessments, reviews and discussions. For the advancement of mid-career digital professionals, performance-based curriculums (identified by Saudi Aramco as ?career professional curriculums?) are also being developed. An overview on how these curriculums are designed based on job outcome requirements will be outlined. UPDC instructors use advanced audiovisual, animation and simulation technologies for effective course delivery and promoting in-class activity participation.
Low BTU Gas Monetisation Technology Commercial Evaluation
Authors: Shabbir Ghulam
Published: May 2016

Natural gas is normally composed of three types of group components; i.e., hydrocarbons, inert and sour components.

The natural gas hydrocarbon component consists of light straight chain hydrocarbons; i.e., methane, ethane, propane, butanes, pentane, etc. The inert component consists of nitrogen and water vapors whereas the sour component normally consists of carbon dioxide (CO2), hydrogen sulfide (H2S), mercaptans, carbonyl sulfide, etc.

The inert and sour components need to be removed to control the high heating value (HHV) of sales gas to a minimum of 930 BTU/SCF to meet the desired fuel gas specification and to keep sour gas content to a permissible limit in terms of health and safety regulations.

Gas purification and treatment technologies are required for removing the inert and sour gas components. Normally, a gas containing more than 20 mol% inert and sour gases is termed a sub quality natural gas (SQNG). This type of gas is normally a lean gas with less heavy hydrocarbon components and has a lower heating value. The inert and sour components need to be removed to meet the sales gas and fuel gas specifications.

The Kingdom of Saudi Arabia has various undeveloped low BTU gas fields with significant gas reserves in the southern and northern part. Low BTU or "trash" gas monetization is required to meet the Kingdom's growing future gas demand, minimize crude oil burning and spare crude oil for export.

The Saudi Aramco Gas Operation department is responsible for future gas development as well as the operation and optimization of the existing gas plants. Due to the growth in energy demand in the kingdom, Saudi Aramco is considering and evaluating whether it should develop low BTU gases. In this regard, Saudi Aramco has undertaken several initiatives and carried out many technical and commercial studies to develop and monetize gas resources.
Applications of Bio and Nanotechnologies in the Oil and Gas Industry. Recent Progress
Authors: Hobbulovich Zaynullov Timur , Abdulaevna Magdova Lyubov
Published: May 2016

The efficiency of oil extraction from oil-containing reservoir is unsatisfactory all over the world. The average oil recovery among different countries is from 25 to 40%. Unrecoverable oil resources reaches up to 70% from the geological oil reserves. Besides it should be noted that major oil fields of the oil-producing country, including certainly Russia, move to the late stage of development, characterized by a passive increase in water cut and decrease of oil production. However, the oil reserves in the fields with water cut over 90% at the late stage are formidable. Therefore creating of new extracting technologies is an actual problem nowadays.

For example nanoparticles with noticeable alteration in optical, magnetic, and electrical properties compared to their bulk counterparts, are excellent tools for the development of sensors and the formation of imaging contrast agents. Nanosensors deployed in the pore space by means of «nanodust» can provide data on reservoir characterization, fluid-flow monitoring, and fluid-type recognition.

As for production nanomaterials-based solutions can contend with corrosive impurities, high temperatures and pressures, shock loads, abrasion, and other hostile environmental conditions. Drilling equipment and platforms can be made or coated with nanomaterials for improved corrosion-resistance, wear-resistance, shock-resistance, and enhanced thermal conductivity.
A Methodology for Rapidly Predicting and Minimising Solid Particle Erosion in Oil-Gas Equipment
Authors: Wong Chong Y. , Solnordal Christopher B. , Boulanger Joan
Published: May 2016

Solid particle erosion in exploration and production equipment poses an inherent risk to all oil and gas facilities. As such, pre-emptive measures need to be employed to predict the longevity of these equipment. This paper presents a methodology to rapidly focus on the qualitative erosion hot-spots and to quantify the local erosion rate on a specific equipment both experimentally and numerically. A qualitative multilayer paint erosion modelling is first applied to the object of interest. This assumes that erosion of the paint surface is similar to the erosion rate trend of the target metal of interest. This is followed by quantitative surface profile measurements in the vicinity of the erosion hot-spots. Computational fluid dynamic (CFD) simulation of the particle flow path and subsequent impacts on the parent surface is conducted. However, prior to conducting the CFD simulations, an empirical erosion sub-model is required. This sub-model is obtained by fitting empirical curves to data obtained from physical erosion of cylinder-in-pipe samples. Once validation with experimental data is achieved, optimization can be made using computer-aided design and CFD to minimise or eliminate the erosion hot-spots. The present paper illustrates this technique via simple flow configurations commonly occurring in exploration equipment and production pipelines.
Successful Implementation of Zirconate Borate Based Dual Crosslinked Gel and Continuous Mixing System During Proppant Fracturing Treatment in a Complex High Temperature and High Pressure Sandstone Gas Reservoir in Saudi Arabia that Exceeded the Well Objective and Showed Substantial Increase in Operational Efficiency - A Case Study
Authors: Driweesh Saad M. , Al-Atwi Mohammed A. , Malik Ataur R. , Duarte Olarte Jorge E. , Leal Jauregui Jairo A. , Bolarinwa Simeon  O.
Published: May 2016

The success in a proppant fracture treatment depends on achieved effective fracture half-length and vertical proppant distribution. The desired fracture geometry can be challenging to achieve in deep and heterogeneous sandstone reservoirs in Saudi Arabia where temperature (up to 350 °F) and pressure are very high. Conventional borate based cross-linked polymer guar gel as a fracturing fluid — for high pressure high temperature (HPHT) reservoir in KSA — is outside of the optimum envelope as far as required rheology is concerned and exhibits extreme sensitivity to brine quality at bottom hole static temperature (BHST). A new fracturing fluid consisting of Carboxymethyl-Hydroxypropyl Guar (CMHPG) crosslinked with dual-crosslinker (Borate and Zirconate) has been found to be a more suitable fluid — than only borate based crosslinked fluid — for HPHT gas wells. This new fracturing fluid provides stable rheology under bottom-hole conditions, is compatible with reservoir fluids, and has excellent proppant-suspending and leak-off properties, while providing improved retained proppant permeability.

Most sandstone gas completed with cased-hole or Multi-Stage-Frac completions in Saudi Arabia require large size proppant fracture treatments. The base potassium chloride (KCl) brine and linear gel are batch-mixed prior to fracturing treatment. This batch mixing process is time consuming and takes up to 3 days per stage fracture treatment. A significant increase in operational efficiency and fracturing fluid quality was observed when all fracturing additives, including: solid polymer and liquid Organic Clay Stabilizer (OCS), a KCl substitute; were used on-the-fly in a HPHT gas well during proppant fracturing treatment, utilizing an advanced continuous mixing system. The advanced continuous mixer was a pumping and blending system that provided linear gel to the blender. The system continuously metered and simultaneously mixed dry polymer powder to produce a gel at desired concentration that was completely free from oil-based material. A total of eight additives were added on-the-fly, utilizing solids and liquid additive system mounted on advanced continuous mixing and blender units.

This paper provides details on lab testing, treatment design, field implementation, and treatment evaluation of a complex HPHT gas well in Saudi Arabia using the novel fracturing fluid system and state-of-art Continuous Mixing System.
A Multi-Well Performance Particle Gel Injection Evaluation Using a Sophisticated Simulator
Authors: Zhou W. , Wang Z. , Delshad M. , AVaravei A. , Wang X. , Zhang W.
Published: May 2016

All major pay zones in Xishugang oilfield in the eastern China had reached 90% or more water cut by the year of 2009. Studies have shown that a lot of bypass oil remaining in the reservoir and the question is what the effective approach is to improve the oil recovery after the over 30 years water flooding and over 4 years polymer flooding in the mid to high permeability fluvial deposited sandstone reservoir. After new temperature-resistant and salt-tolerant pre-cross linked swellable particle gel (PPG) injection into a few dozen wells as a field trial, we have used a sophisticated simulator to evaluate the injections, and used the calibrated model data to assist the PPG injection design optimizations including pumping rate, PPG loading concentration, lateral pressure gradient maintaining, and total pumping time for over a hundred wells. The results are very encouraging. An over half million tons oil production increment have been estimated since the PPG injection has been in place during last 2 years, and the general investment input and output ratio is over 4.5 has been achieved during the first two years of this operation.
Evolution and Application of Geoscience Technology to Integrated Reservoir Characterisation for Enhanced Heavy Oil Recovery - Cold Lake Field, Alberta, Canada
Authors: Elliott Andrew , Eastwood John , Magennis Lochlann
Published: May 2016

The Cold Lake heavy oil field in Western Canada was discovered in the late 1950's and contains approximately 5.3x109 m3 (33 billion barrels) of heavy crude bitumen. Commercial production utilizing Cyclic Steam Stimulation (CSS) commenced in 1985. By the end of 2010 over 159x106 m3 (1 billion barrels) of bitumen had been produced. The Cold Lake Heavy Oil field currently produces approximately 24,000 m3/d (150,000 barrels per day).

The geological models and concepts that supported early production were based on well log and core data only. Early use of 2D seismic data showed limited utility for imaging the high net-to-gross reservoir. However, the advent of high-resolution 3D and 4D seismic in the early 1990's provided renewed interest in seismic data for imaging thermal processes. These early "4D" surveys were small in area but provided data critical for imaging the steam heated regions (thermal conformance) in the reservoir and managing follow-up drilling and completion strategies. Recent advances in 3D and 4D seismic processing and analysis now allow quantifiable estimations of thermal reservoir conformance to guide enhanced recovery methods and depletion planning.

A novel use of microseismic technology was developed in the mid 1990's to assist in the early detection of casing failures and fluid releases into the overlying shales and aquifers to mitigate environmental, safety and economic consequences. Since 1998 microseismic monitoring has been integrated into commercial operations and with our interpretation of depositional geometries to further our understanding of steam migration. Today, Cold Lake has more than 100 dedicated microseismic monitoring wells making it one of the largest microseismic monitoring networks in the oil and gas industry.

In the mid 2000's larger, high-frequency 3D seismic surveys were acquired for reservoir characterization. 3D seismic data are integrated field-wide with other data to build predictive geologic models and to assess recoverable bitumen volumes for multiple extraction technologies. These models enable maximum efficiency of resource development while reducing reliance on relatively expensive core data. Several enhancements to the recovery process are in the testing stage today to improve existing development or facilitate future developments in more challenging resource areas. Continued geoscience data collection and integration will drive efficient development of these new opportunities.
Integrating Fresh Methodologies, Technologies and Atypical Procedures Leads to Outstanding Production Enhancement Results in a Mature Field
Authors: Cavallaro Brandon , Shoreibah Ahmed , Stefanescu Dan Paul
Published: May 2016

The work completed was a comprehensive look into a mature gas field's intervention and production history to identify underachievement, redevelop the field management plan and implement successful remediation operations. The identification and characterization of skin was initially completed with physical inspection and slickline techniques. The decline curve analysis applied adapts to erratic declines from changing wellbore conditions, unreliable, or incomplete histories and provided accurate production forecasts. Pumping and coiled tubing techniques were used in the remediation work.

In 2003 an Association was formed to manage a mature Romanian gas field producing since 1970. Production skin was evident and in 2010 the first well failed due to halite formation; consequently, liquid and solid sampling tools were deployed within suspect wellbores. The damage was characterized (halite, calcite and water blockage), novel decline curve analyses detected underperformance by integrating cumulative production histories.

Twenty-two wells from one zone were initially assessed. All were damaged with some showing physical evidence of scale or salt, and a seven well pilot intervention campaign resulted in 38% peak incremental production. The outstanding results matched decline curve expectations and led to a full-field study, a campaign to intervene over half of the field based on that study, and possible expansion to all remaining wells in subsequent years. Technically, the innovative decline curve analysis proved crucial to discovering opportunities. Operationally, the optimized intervention procedures introduced were new to the basin and have been adopted by the Association partners in other assets.

A major limit on ultimate recovery from depleted hydrocarbon reservoirs is declining well productivity. Salt formation, scale deposition, and water loading restrict flow: reducing production rates and increasing operating costs due to remedial interventions. Therefore, economical skin management is an essential tool for extending field life, increasing profitability, and improving recovery factors from aging assets. Impressive results led to a strategic shift in local field production management and the techniques are useful worldwide in similar fields.
Characteristics and Origin of Microfracture in Lower Cretaceous Tight Sandstone from Kuqa Foreland Basin, NW China
Authors: Chun Liu , Qingxin Guo , Ronghu Zhang , Huiliang Zhang
Published: May 2016

The Kuqa basin, as a secondary tectonic unit of Tarim basin, located at the front of the south Tianshan Mountain, is a foreland basin formed in the Late Tertiary. The Lower Cretaceous Bashijiqike tight sandstone in the basin is an ultralowpermeability and low-porosity reservoir. Microfractures, such as intragranular microfractures, grain-edge microfractures, and transgranular microfractures, are abundant in the tight sandstones. Microfractures improve storage and permeability and impact distribution of natural gas. Microfractures have a wide range of sizes, shapes, and patterns, but most of them are opening-mode fractures. Microfractures reflect tectonic, overpressure, and diagenetic origins. Based on fluid inclusions, carbon-oxygen stable isotope analysis of fracture-filling cements (calcite and dolomite) and burial history, tectonic microfractures were determined to be formed before early Miocene and at the middle of Miocene. In the middle to late Himalayan movement, the tension microfractures closed and were filled with carbonate cements. Microfractures related to overpressure, being tension microfractures, are commonly filled with bitumen and were formed at the end of Miocene. The transition of stress state from compression to tension by overpressure is the reason that tension microfractures were formed in the compression setting. Diagenetic fractures were formed at the end of the Late Cretaceous to Paleogene. Under intense compaction, grain-crushing crackle fractures in quartz and cleavage fractures in feldspar formed intragranular microfractures. Some transgranular microfractures and grain-edge microfractures caused by diagenesis are along the bedding plane and parallel to the directional mineral grains.
Pitting Corrosion Failures of Natural Gas Transmission Pipelines
Authors: Mansoori Hamed , Mirzaee Reza , Mohammadi A.
Published: May 2016

This paper addresses frequent failures of natural gas transmission pipelines in one of the Iranian gas production fields. The three phase flowing fluid consists of 0.15 to 0.384 mole fraction of carbon dioxide with an average of 9 bbl/mmscf water cut. The material of 10-in flow lines are API 5L X65. Internal corrosion is mitigated by means of amine type corrosion inhibitor (CI). The fluid corrosivity, optimum concentration and injection rate of CI determined by means of polarization electrochemical tests and field data. Internal corrosion monitoring tools are including of weight loss corrosion coupons, electrical resistance(ER) probes and Iron counting in compliance with NACE standards. The occurred destructions differ in low and high off take gas wells. Having finished the pipeline construction, the free water left in some pipelines from hydrostatic test (a gap between hydrostatic test and pipeline operation) accelerated the initiation of corrosion process. During pipeline operation, the dissolved oxygen in diluted CI helps merging electrochemical cells under the deposits and this led to pitting corrosion. Generally, the deposit compositions are including Magnetite, Hematite, Wustite, Iron carbonate and Calcium carbonate. For high off take gas wells, erosion/corrosion phenomena observed in wellhead facilities. In such wells, the uniform corrosion is a consequence of deposit removing by higher velocity of the fluid. An intelligent pigging MFL was performed in one of the damaged flow lines in order to estimate the dimension of corrosion damages. Immediate actions are foam cleaning (chemical washing) to remove the deposits on the pipe wall and the possibility of using oxygen scavenger in the chemical injection packages in order to alleviate dissolved oxygen in Diluted CI.
Technical Master Classes - A New Approach to Knowledge Transfer
Authors: Gully Crystal , Feeley Missy
Published: May 2016

Technical master classes are a new training concept designed to accelerate building expertise among geoscience, engineering and commercial professionals. The ExxonMobil master class concept emphasizes transferring knowledge and thinking processes from experts to practitioners through a training process that is a blend of mentoring and traditional technical training. Rather than only teaching factual knowledge and technical concepts which dominate traditional technical training classes, the master class learning experience simulates real technical situations so that the experts can coach practitioners' thinking through the complexities of an issue.