bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization and Simplification Technology of Maturing Oilfields Gathering and Transportation System and Water Injection System
Authors: Zhao Xinming , Zhou Song , Xu Guoan , Xiang Yong , Li Qing , Zhao Ming , Xia Minmin , Zhu Kaifeng
Published: January 2020

In the later stage of development of Dagang Oilfield, many problems, such as inadaptable process, severe corrosion of equipment, high energy consumption and high maintenance cost, have been presented in the oilfield surface system. Through the research and field application of the optimization and simplification technology of surface system, the technology series of optimization and simplification with Dagang features has been formed. This article focuses on oil well software metering technology, intelligent control technology of water injection wells, oil well single-pipe transportation technology, gathering and transportation and water injection process optimization technologies.

Through the research and application of the optimization and simplification technology of surface system, the metering technology and the single well oil collection technology were simplified, the metering station was cancelled, the mixed water system was shut down, the oil and water pipe network and the process flow were shortened. The production and operation cost, system operation and maintenance expenses and construction investment have been descended evidently. It also has a significant effect on energy saving and consumption reduction and explores a new road for improving the development efficiency and sustainable development of old oil fields.
Modeling Hydrodyanmic Roughness in the Lubricated Pipe Flow of Unconventional Oils
Authors: Rushd Sayeed
Published: January 2020

Water-lubricated pipe flow is an economically efficient and environmentally sustainable technology to transport unconventional oils like heavy oil and bitumen. The internal wall of the pipe carrying the water – heavy oil mixture can be "fouled" by the viscous oil in the large-scale applications of the flow technology. The hydrodynamic effect due to wall-fouling has not been previously addressed, albeit its importance in modeling the frictional pressure losses in wall-fouled pipes. A new methodology to model the hydrodynamic or equivalent sandgrain roughness in a lubricated pipeline is proposed in the current study. The equivalent roughness is determined by simulating the measured value of pressure loss. ANSYS-CFX platform was used for the CFD simulations. In addition, a correlation was developed for the roughness based on a dimensional analysis. It is important to the engineers operating and/or designing water-lubricated transportation lines.
Carbonate Matrix Acidizing Efficiency from Acidizing Induced Skin Point of View: Case Study in Majnoon Oilfield
Authors: Al-Rekabi Mostafa Abdulkareem , Aktebanee Ahmed , Al-Ghaffari Adham Sabah , Saleem Tahir
Published: January 2020

The main objective from carbonate matrix acidizing design is to enhance the wormhole network and to avoid any induced damage caused by treatment fluid and pre flush/post flush fluids. Optimization of treatment fluid recipe aims to avoid potential source of damage such as sludge, emulsion and wettability alteration to maintain the new acquired permeability in the acid injection phase. The skin factor trend is modeled during injection and clean up phases to assess matrix acidizing interaction with formation.

This paper will be focusing on real-time skin trend monitoring model which takes wellhead pressure and flowrate values as a two main parameters for formation response interpretation during both Acid injection and flow back clean up phases. Injection multi-rate drawdown well test model was used to monitor the skin trend for injection phase and used forward multi-rate drawdown test model for clean-up flow back phase in post soaking period. The permeability contrast was considered to monitor the diversion effect.

During post flush phase, the treatment fluid (15% Acid including additives) was squeezed into the formation using post flush #1 (mainly solvent system) followed by post flush # 2(mainly 2% formic acid). The wells left shut-in for prolonged soaking period (24 hours). The results show that Skin trend at the end of flow back phase is more than skin value at the end of injection phase by considerable difference which indicate induced and added skin value. The suspect for the source of this increased skin value could be either prolonged soaking period and/or non-optimum treatment fluid design. During flow back period, excessive fluctuating in BS&W and pH was observed which can imply water block and rock wettability alteration.

The ratio of Productivity index at the end of clean-up to the index at the end of injection phase is defined in this paper as "Stimulation Efficiency" and the difference in the skin value at the end of acid injection and the skin at the end of clean up phase defined as "Acidizing Induced Skin" value. The average of this added Skin value ranges from +3 up to +10 with 30% to 40% average stimulation efficiency which lead to increase in skin value that was lowered during acid injection. Production test after each acidizing job validated the skin value ranges at the end of clean up phase.

This efficiency value combined with BS&W trend and content behavior during clean up phase, will give the stimulation engineer an overview to optimize the acid additives and post flush recipe to mitigate above mentioned damages.
Decision Support System for Optimizing GOSP Operation
Authors: Al-Dossary Badr , AL-Naser Mustafa , Al-Dogail Ala , Gajbhiye Rahul , Al-Qathmi Ahmed , Mahmoud Mohamed
Published: January 2020

It is very important to consider all the units and operating parameters of the individual units in the gas-oil-separation-plant (GOSP) optimization process. For many processes, optimum parameters for the individual units are difficult to implement in the real operation especially for GOSP in which all the units are connected to each other and establishing the optimum control condition for the individual unit will be difficult to implement.

The objective of this project is to develop a generic integrated framework for maximizing the oil recovery by optimizing the gas-oil-separation-plant (GOSP) parameters. A typical Saudi Aramco GOSP plant has been considered as the candidate for the project. In this project, a model consists of multi-stage separators, and stabilization units along with the stock tank to mimic the oil train. Amongst the various parameters, only the controllable parameters such as pressure, and temperature were considered as optimization parameters to achieve the maximum oil recovery. The GOSP plant model was developed using OmegaLand software.

To evaluate the effect of the various parameters many runs were initiated for generating the data. A model is developed by applying artificial intelligence techniques to the data generated by the simulator. The model served as a tool for optimizing the controllable parameter to achieve the maximum oil recovery which is the ultimate goal of the GOSP plant. The generic integrated framework serves as a guide to set the optimum operating condition for maximizing the oil recovery. The optimized parameters can be adjusted by Operation Decision Support System (ODSS).
Slimline High-Speed ESP Application for High Value, Restricted Diameter Wells
Authors: Zabala Wilson , Lastra Rafael , Demarque Vianney , Xiao Jinjiang , Mutairi Khaled
Published: January 2020

Electric Submersible Pump (ESP) is the most appropriate artificial lift method for moderate to high production rate wells. However, there are shortcomings in ESP technology for applications in slim casing wells with high rate production potential. These applications include wells in which liners as small as 4 ½′ have been installed inside the original casing for well integrity remediation. Some of these wells can produce high rates, however after the slim liner installation, production in these wells must be curtailed to the maximum production allowed by existing slim ESP technology. In addition to that, performance and reliability of current slim ESP technology is subpar compared with larger diameter ESPs.

This paper discusses the development of a new High-Speed High-Rate Slim ESP system that can be installed in casing applications as slim as 5′ and 4 ½′ and it is able to produce higher rates than standard technology. The discussion includes the considerations for the design, the testing plan and the qualification testing results.

There are many challenges associated with the design of an ESP to produce high rates in small diameters. This paper discusses mechanical and hydraulic considerations and the evaluation of trade-offs between efficiency, rotational speed and production rate, among others. Since this is a new technology with much higher operating speeds than standard ESPs, there are currently no applicable industry test standards. This paper presents the approach taken to develop the testing and qualification plan, as well as the results obtained during the testing phase.

This new ESP technology was demanded to operate under very challenging conditions including tight clearances, harsh environment and high fluid velocities. The testing results showed that the system design met the production requirements while maintaining appropriate levels of performance.

The newly high-speed/high-rate slim ESP incorporates multiple innovative design features developed to increase both performance and reliability of the system. Some of these features include a new Permanent Magnet Motor (PMM) design with an advanced control system, a high-frequency variable speed drive, a shaftless protector design, a new slim ESP sensor with high speed data transmission and ground fault capabilities, as well as a new flow/power crossover system with highly reliable electrical connections.
Advanced Modeling and Sensitivity Analysis for Downhole Wet Gas Compressor Applications.
Authors: Lastra Rafael , Montoya Cesar , Aladawy Ahmed , Malkawi Ameen
Published: January 2020

Downhole gas compression (DHGC) in gas wells is a relatively new concept in production engineering, but it represents one of the most promising technologies to revive dead wells, to boost gas production and to maximize total gas production recovery. This technology could be analogous to electrical submersible pumps (ESPs) for oil wells, as it increases well production by reducing the back pressure at the wellbore sand face; this is achieved by providing boosting pressure to cover for outflow pressure requirements (i.e. tubing losses and well head backpressure). However, downhole wet gas compression applications are considerably more challenging than those for ESPs. The purpose of this paper is to describe step by step the procedures and workflows to evaluate downhole gas compression applications, from information preparation, to multiphase flow calculations and sensitivity analyses.

The applications of this technology are more complex than conventional pumping methods for oil wells. Calculations are more involved with considerations for gas compressibility, multiple flow regimes, liquid volume fraction at compressor intake, compressor pressure ratio requirements, liquid loading conditions, discharge pressure and discharge temperature, among other effects, which are some of the main factors to be measured for this type of application.

There is no standard methodology in the oil industry for gas well modeling and sensitivity analysis for DHGC applications. Just few publications can be found in the literature with some description of the evaluation process but missing some other relevant aspects of the application. This paper presents a systematic process to evaluate applications of DHGC including well performance modeling and compressor simulations.

A new comprehensive methodology has been used for downhole compression application in this study, using nodal analysis software for well performance modeling in combination with a process system simulator to model compressor performance.
Unconventional Field Well Delivery Optimization: Drilling Precise Sand-Channel Targets
Authors: Almasmoom Salahaldeen , Le Viet , Stonestreet David , Al-Faraj Omar
Published: January 2020

The surge in the worldwide demand for hydrocarbons has resulted in considerable interest in drilling for unconventional resources. The Drilling Engineering Team has reduced the duration and cost of drilling wells by 80% in drilling days and 73% in well delivery cost while targeting more precise sand-channel targets in the Unconventional Field presented in the paper, during a time period of about 10 years.

Optimizing the casing design (moving from seven casing strings to four casing strings), drilling practices (maximizing drilling parameters), and completion practices (moving towards 4-½-in cemented longstring instead of lower/upper completion), resulted in reducing the number of days and the associated drilling cost. The improvements include:

Modifying hole sizes (slimming wells starting from 34-in section to 22-in section).

Combining sections that were previously isolated (for example, combining the targeted sand-channel reservoir with a long shale interval above it in one section).

Eliminating drilling liners and completion tiebacks (moving towards 4-½-in cemented longstring instead).

Improving the drilling fluids program (moving towards high salinity NaCl polymer drilling fluid system for the shallower sections, and reducing mud weights needed to stabilize the long shale interval from 100+ pcf toward 70-80 pcf by utilizing OBM),

Increasing top-hole rate of penetration by strategically moving all the directional nudging into the 8-½-in/8-⅜-in OBM drilled hole section, and decreasing cost of top hole bottomhole assemblies.

Introducing new technology 8-½-in/8-⅜-in PDC bits that drilled the entire hole section with one bit.

Introducing an updated combined logging program.
A Hydrocarbon Production System Multi-Objective Optimization
Authors: Rizzo Cascio Joseph , Di Maio Francesco , Bianco Amalia , Ritondale Sergio , Cadei Luca , Montini Marco , Rinaldi Fabio , Zio Enrico , Najafi Behzad
Published: January 2020

The benefits of a multi-objective optimization approach embedding an accurate exergy model of a hydrocarbon production system are shown on a real oil and gas facility. The innovative tool developed is based on a biogenetical differential evolution algorithm, which exploits a self-adaptive iterative procedure to maximize the value of the Asset. The optimization integrates the production system considering the trade-off between hydrocarbon production, energy consumption and efficiency. The Asset value optimization is one of the most complex and multi-disciplinary task in the oil and gas industry, due to the high number of objectives and their synergy. An integrated physical model of wells, gathering network and process plant is built and, then, used for exergy efficiency and gas production optimization. Conflicts and interactions among process variables and operational constraints are treated and solved holistically by the tailored evolutionary algorithm. This has also been integrated with a quick and efficient exergetic and thermoeconomic analysis in order to grant the achievement of the maximum asset value. The multi-objective optimization provides a trade-off between the optimal values of exergy efficiency and gas production that would have been obtained independently with single-objective optimizations. In fact, the exergy efficiency optimization is driven towards a configuration having lower irreversibilities: by apportioning the entire system exergy into the exergy destroyed by each piece of equipment and by calculating its local efficiency, the most contributing to irreversibility generation is identified. Moreover, the exergy analysis is complemented with an exergetic and a thermoeconomic cost analysis: the exergy analysis, apart from describing the quality of any thermodynamic process, does not give any information about the costs of each system stream, which can be even more interesting and of practical application. Indeed, the exergy analysis is proven to be an accurate way of assessing which equipment is performing worse. Therefore, it leads to preventive corrective actions to ensure good thermodynamic performance of the system and supports the decision process in the choice of maintenance operations. The thermoeconomic analysis, based on the theory of exergetic costs, confirms the improved management of the process plant and its efficiency enhancement, without neglecting the main target of the oil and gas industries that is production maximization. The benefits of a novel multi-objective biogenetical approach to solve and optimize a hydrocarbon production system in terms of exergy efficiency and gas production are shown, with respect not only to other methodologies of literature but also in terms of exergetic and thermoeconomic costs of the solutions provided, allowing to achieve the highest value of the operated asset.
Challenges of Pressure Transient Analysis PTA: Uncertainty Assessment and Pitfalls in Well Test Analysis-How Much Confidence Does a PTA Interpretation Has?
Authors: Cobanoglu Mustafa , Shukri Ibrahim
Published: January 2020

Pressure transient analysis (PTA) is one of the best tools to estimate critical well and reservoir parameters. Some of those are reservoir properties, reservoir size and shape (i.e. permeability, fracture properties, reservoir model, distance to boundaries, etc.), completion efficiency (i.e. skin, fracture performance…etc.), tubing performance (i.e. optimum tubing design and artificial lift requirements) and well (i.e. fracture performance, skin, etc.), and reservoir characterization (i.e. dual porosity, layered reservoir, composite, etc.). Therefore, proper interpretation of PTA is crucial to acquire critical parameters for field development and well optimization. Pressure transient analysis technology has improved over the time. However, real-life examples of pressure data to fit a given idealized model are often nonexistent. In addition, well test interpretation suffers from a variety of uncertainties that combined, to reduce the confidence of the analyses. This paper attempts to summarize the uncertainties associated with well test analysis, shows examples of pitfalls in well test analysis, and provides the methods that proposed to identify the uncertainties.

The first phase of the project, a detailed analysis of several PTA interpretations collected from various oil and gas fields in Petroleum Development Oman (PDO), compiled and analyzed to identify the main areas of uncertainty. In the second phase of project, best practices for well test interpretation methods were developed to achieve a consistent interpretation approach across the company. In the third phase of project, five main sources causing an uncertainty on PTA interpretation were investigated, analyzed and demonstrated with relevant actual examples, as well as demonstrating the pitfalls in well test analysis.

The study proposed and developed a six-step PTA interpretation Work Flow including QA/QC steps and the study identified five main uncertainty areas, developed techniques to evaluate each of these, and presented the pitfalls of each uncertainty. Those key uncertainty areas are:

The uncertainty in reservoir properties

The non-uniqueness of the PTA model responses

The limitation of the data set

The physical error in the pressure / rate data (including non-reservoir effects on pressure gauges response such as gauge drift) and the human effect

The implications of well bore storage effect

This document provides a summary and characterizes the five main sources of PTA uncertainties through actual data from PDO in the Sultanate of Oman. This document will also cover the best practices and workflow that have been developed & proposed in order to achieve a step change in the quality and reliability of the PTA interpretations. The implementations of the workflow are presented for a variety of reservoir types and field examples of its implications on well optimization and field developments will be shared.
Building Technical, Commercial and Soft Skills in Evolving Organizations
Authors: Howes C. Susan , Taylor Robert W.
Published: January 2020

The combination of unevenly distributed demographics and the recent industry downturn have resulted in an exodus of highly experienced workers from the oil and gas industry as employers constrained costs by reducing headcount. Retirement of highly skilled technical experts has further compounded these critical issues. The remaining workforce is talented, but many organizations are experiencing significant capability gaps that are driven from their workforce being inexperienced, under-trained, and lacking access to qualified mentors.

Addressing capability gaps requires an understanding of what skills are needed. New leaders may not be aware of the full spectrum of technical skills, and which skills are best applied to technical challenges. Many leaders manage cross functional teams where several team members work in different disciplines. Once appropriate skills are identified by job functions necessary to perform the work, companies inventory skills and competency levels in their organizations. Individual development programs are developed utilizing available training and development resources to target the gaps and effectively raise the level of competency within the required timeframe.

A complete program includes:

Competency modeling and assessment

Conventional classroom instruction and exercises

E-learning libraries

Virtual learning options

In-house and virtual mentoring

Business workshops and simulations

Rotational assignments and "On the Job" (OTJ) training

Consulting experts to fill gaps temporarily and allow time for staff development

Subject matter experts to provide peer reviews to ensure quality

Successful implementation of a competency based focused training and mentoring program drives companies to close the identified capability gaps and increase business performance. This presentation draws on several successfully implemented programs to demonstrate the applicability and relevance of the program's key elements leading the organization to an increase in overall workforce skill levels.

These referenced examples describe key elements of a competency management system (CMS) implemented by E&P companies globally. The CMS system includes building competency models, developing employee and supervisor assessments, and creating learning plans for employees in both technical and business support positions. The competency models will reflect models that have been approved by the Society of Petroleum Engineers and the Society of Exploration Geophysicists, adding a global standard to the program.

By using the CMS for assessments, senior management can clearly monitor and determine its current competency levels, measure its progress in eliminating competency gaps, identify the competencies that need further development, and update individual learning plans. The expected outcome changes the dynamics of personnel development from curriculum-based training to competency-based in order to accelerate the skills that are required for the company and their specific applications.
Novel Method to Estimate Bottom Hole Pressure in Multiphase Flow Using Quasi-Monte Carlo Method
Authors: Opoku Daniel , Al-Ghamdi Ahmed , Osei Albert
Published: January 2020

Estimation of flowing bottom-hole pressure in multiphase flow is done through empirical correlations like Beggs and Brill or Gray correlation. These correlations were developed in time when computing power was limited and some were developed based on water-air mixtures, making them less accurate in real oil and gas production scenarios. Regardless, due to lack of other alternatives, general empirical correlations, like the ones mentioned previously, are widely used in the industry for estimating flowing bottom-hole pressure in multiphase flow.

Machine learning and Artificial Intelligence (AI) are emerging techniques in analyzing a large set of data to identify relations and patterns in multivariate problems. The method used in this paper – Quasi-Monte Carlo (Latin Hypercube sampling) – randomly selects input data to create empirical correlations between flowing parameters and bottom hole pressure. In this study, production data (oil, gas, water flow rates, and flowing wellhead pressure) from an oil well is used as input, and an algorithm based on Latin Hypercube sampling selects random variables from each of the parameters to generate several correlations. The correlation with the minimum error is chosen.

From the developed equation, the calculated flowing bottom hole pressure was within an average error of 5%. The advantage of this method is that it does not require any tubular information, such as tubing internal diameter, surface roughness, or tubing restrictions. In addition, the average reservoir pressure can be estimated from the constant of the model. Furthermore, the application of this method can be used to indirectly infer several fluids or rock properties.

This is a novel method to statistically estimate flowing bottom-hole pressure using only production data. This method can also be expanded to gain knowledge about other reservoir properties.
Novel Application of Magnetic Flux Leakage-Based Technology Validating Pipe Elongation in Coiled Tubing Drilling Operation
Authors: Wiranata Kevin , Ridene Arafet , Yusoff Mohd Nur Afendy Md , Hamdi Abdullah , Sa Rodrigo , Chaari Youssef , Arifin Mohammad
Published: January 2020

Coiled tubing drilling (CTD) uses wireline inside coiled tubing (CT) for real-time downhole measurements and controlled actuation of the bottomhole assembly (BHA). In the CTD case under study, after several hundred thousand running feet, the wireline disconnected from its BHA anchor, resulting in lost communication and nonproductive time. By using the input of a CT integrity monitoring system based on magnetic flux leakage (MFL), it was shown that the CT experienced linear plastic elongation, resulting in the wireline being disconnected from the BHA anchor.

CT pipe is fabricated from metal skelps joined together with bias welds. The pipe integrity monitoring system based on MFL was used from the first run of a CT string until its last run, before retiring the pipe. The system was originally designed to detect defects along CT string, but it can also analyze bias weld profile, which cannot be seen outside the tubing. Lengths of each metal strip were noted by comparing the distance between two bias weld points in the same run. CT elongation was then determined by comparing the length of each strip from initial and subsequent runs.

This paper comprehensively studies CT elongation growth over each run and elaborates on the consequence of this elongation for CT operations using wireline or fiber optic cable (e.g., jeopardizing operations). The outcome from this paper helps to prevent recurrence by recognizing the root cause and modifying the slack management practices especially for this operation, which is sensitive to accurate slack calculation.
Curing Losses with Bio-Degradables: Challenges and Feasability of Particle Size Distribution
Authors: Omer Mohammed , Fragachan Francisco
Published: January 2020

Lost Circulation currently accounts for loss of approximately around $850-900 million USD per year. Middle East is probably counting for a major part of these losses. This research paper reviews the current practices of LCMs, different polymeric materials used, and this paper will explore new ideas revolving around biodegradables as part of our commitment to make the industry cleaner and greener.

Drilling of Oil wells is encountered with a host of technical problems that often makes it difficult to develop some of the fields. Lost circulation is one such critical issue defined as the continuous loss of drilling fluid when it encounters fractures, vugs, highly permeable zones during drilling. If not controlled Lost Circulation can lead to stuck pipe issues, wellbore stability issues and ultimately can lead to blowout endangering life and property.

Despite several technological advances in this area, Lost Circulation Materials (LCMs) today has many drawbacks such as damaging the formations, failing to seal the fractures and damaging the environment. This paper presents the feasibility of various lost circulation materials and explains the physics behind the particle size distribution necessary to have an effective sealing and jamming. An analytical model based on CFD-DEM (Couple Flow Dynamics & Discrete Element Modelling) has been developed, calibrated with experimental results and existing models to optimize the parameters. It discusses about the need of new engineering for designing LCM success performance

We are focusing on possible use of plant based degradable renewable materials which degrades back to liquid state as a potential lost circulation material in this paper. The engineering analysis will focus on optimizing the LCM in relation to fracture dimensions.
Emerging Fluid Design with Enhanced Proppant Carrying Capacity: An Integrated Geomechanical Workflow
Authors: Perez Oswaldo , Fragachan Francisco E. , Omer Mohammed , Huang Jian
Published: January 2020

The overall success of a hydraulic fracturing treatment and the resulting fracture properties, such as length, height extent, and conductivity, are dictated by the proppant -transport- distribution and its mechanical behavior -effectiveness- within the stimulated fracture network. With the goal of minimizing (eliminating) proppant settling and optimize required horse power on location reducing equipment foot print and volume of water required; an engineered low-viscosity fluid with high proppant carrying capacity has been implemented to improve proppant transport and zone coverage in stimulated fracture networks. An integrated methodology to optimize the emerging fluid design and proppant placement, is presented.

To evaluate and quantify the efficiency of the proppant transport process with a novel low viscosity fluid, an integrated geomechanics workflow was developed combining quick look analysis (i.e. candidate selection) with advanced computational models (i.e. geomechanical models) to improve proppant deliverability. Experiments were conducted to quantify the shear thinning behavior and proppant carrying capacity of the engineered fracturing fluid under different flowing conditions. By honoring experimental results, multiple analytical and numerical models/modules were developed and utilized within the framework of the workflow to assess the designed efficiency.

The novel fracturing fluid is characterized as low viscosity (comparable to that of linear gel), yet it can suspend and transport conventional proppants similarly to a high-viscosity fluid (e.g. crosslink gel), decoupling the need for viscosity with proppant transport. Our analysis indicates that the fluid design (viscosity & proppant carrying capability) and proppant selection type should be customized and evaluated based on the local GeoMechanical conditions. If engineered accurately, fit-for-purpose, fluid can effectively distribute proppant into the fracture surface area, sustaining closure stresses, reducing embedment, and achieving longer effective fracture length(s) and larger conductive reservoir volume with enhanced production.

The formulated workflow can provide an optimized design or improve existing designs based on the reservoir properties and field limitations by iteratively optimizing relevant controls (such as fluid design, proppant type, pumping schedule) of a fracturing operation. Our engineered fluid (EF) technology together with a proposed workflow, demonstrates that fluid design and proppant placement and operational parameters can be customized to maximize production, without compromising for settling and zone coverage.
A Multistep Reactive Convection Model for the Prediction of the Dolomite Bodies Distribution in the Karachaganak Field - Kazakhstan
Authors: Gabellone Tatyana , Borromeo Ornella , Consonni Alberto , Geloni Claudio , Albertini Cristian , Bigoni Francesco , Francesconi Arrigo , Lazzeri Riccardo , Vercellino Alberto
Published: January 2020

In the Carboniferous reservoir of the Karachaganak field the occurrence of replacive dolomite improves the reservoir quality. Petrographic and geochemical data on core samples suggest a geothermal convection along the slope as the main dolomitizing mechanism. Despite the significant number of wells, inferring the 3D distribution of these dolomitized bodies from lithological logs analysis only is quite challenging. To improve the understanding on the dolomite spatial distribution, Reactive Transport Modelling (RTM) at field scale has been performed with an in house developed software (MuFloT). MuFloT is a graphical environment designed to perform non isothermal multiphase flow and reactive transport models through a customized version of the TOUGHREACT commercial code.

Dolomitization by geothermal convection in the shallow burial domain was simulated on a 3D grid at the field scale in three discrete steps, following the stratigraphic architecture consisting of an aggrading phase (Layer 1), a prograding phase (Layer 2) and an upper prograding unit dominated by cyclic platform deposits (Layer 3). The geometry of the three layers was obtained by decompaction and tilting of the present-day horizons from the reservoir static model. The grid was populated with five rock domains characterized by different porosity and permeability, which were inferred by extrapolating present-day values to depositional conditions.

The specified heat flux at the bottom boundary in each step generates a heterogeneous temperature distribution with higher temperatures up to 47 °C reached in the subsurface of the platform interior. The temperature difference between the warm platform interior and the colder flanks generates convective half cells causing a seawater influx from the flanks of the platform. This geothermal convection triggers the replacement of calcite by dolomite. Dolomite formed in each step acts as a seed for additional dolomite formation during the subsequent episodes of geothermal circulation. Simulation of all the three Layers (4 Myr in total) drives complete dolomitization on the slope areas in Layers 3 and 2, in agreement with observations from well logs and cores. The modelled spatial distribution of dolomite provides trends and rules for the distribution of lithology and reservoir properties in the reservoir model.
Approach for Wellbore Production Monitoring Using Distributed Acoustic Noise Measurements
Authors: Miklashevskiy Dmitriy , Shako Valery , Borodin Igor , Wilson Colin , Kortukov Dmitry , Tarelko Nikolay , Zozulya Oleg
Published: January 2020

The objective of this study was to develop a data processing flow for the oil and gas industry enabling the determination of inflow profile and fluid type identification for in well oil-water flows, and to quantify the phase and flow rates using distributed acoustic vibration data, in a near real-time wellbore monitoring scenario. The implementation of the approach will enable alarms to be raised in real-time in zones when changes in the flow rates and phase changes exceed predetermined levels, allowing quantifiable operational decisions.

The acoustic data was acquired using a distributed fiber optical (FO) sensing technique and reference hydrophones in a laboratory flow loop equipped with accurate reference flowmeters. The acoustic noise created by the main pipe flow and inflow was studied. Total flow rate varied within the range 0 to 200 m3/d for water and a model of light oil.

A set of numerical models was used to support development of the interpretation approaches through an enhanced understanding of the acoustic field in various real wellbore geometries.

Two interpretation approaches based on laboratory correlations of acoustic noise energy in a selected frequency range and machine learning algorithms were developed to quantify phase rates from distributed acoustic vibration data induced by turbulent fluid flow in laboratory conditions.

It is shown that correlation-based interpretation enables flow quantification and profiling within acceptable uncertainty levels, for a field dataset of distributed vibration measurements and a reference production logging tool (PLT) log in a producing wellbore.

The goal of the software development is to provide a quantitative flow characterization from the interpretation of distributed acoustic vibration measurements. This method was tested using field fiber optic datasets combined with reference PLT log data.
First Worldwide Implementation of Pressurized Mud Cap Drilling for a 17 × 19 in. Hole Section Translates into Safer and More Cost-Effective Operations
Authors: Al-Otaibi Rakan F. , Al-Haqwi Mohammed , Iturrios Carlos O.
Published: January 2020

During the development of drilling operations there are several operational risks and hazards that can jeopardize the continuity of the operation or make it so complicated that the economic burden to drill becomes unacceptable.

Loss of circulation is one of the main causes of cost increase in drilling operations throughout the world and often the formation characteristics, the well design, or the available technologies make it impossible to eliminate this problem.

Studies have shown that drilling fluids represent between 25% and 40% of the total cost of drilling a well . With this in mind it is clear that encountering loss of circulation, and particularly total losses, represents a significant impact on the economic aspect of the operations. Additionally, several cases face the problem that operations cannot continue unless the losses are stopped.
Engineering Design of Multistage Acid Fracturing Operation in a Dual Lateral Well
Authors: Al Jabr Abdullah , Nwachukwu Cosmas , Al Hajri Faleh , Al Nasser Mohammed
Published: January 2020

This paper describes the planning for an application of multi stage acid fracturing in a dual lateral well. It also highlights associated risks and methods to be used for risk mitigation.

Multi-Stage Fracturing (MSF) is considered to be very challenging in dual lateral wells due to the challenges arising from (1) managing the losses after fracturing without damaging the reservoir and (2) isolating cemented junction (known as TAML level 4 junction) from high pressure required for fracturing and stimulation operations.

The unique application of existing technologies such as flapper ceramic valve used in the mother bore and dissolving ball with ball seat installed in the upper lateral is a feasible solution to the challenge of severe losses.

Moreover, the utilization of frac string equipped with seal assembly that stings into an extended Polished Bore Receptacle (PBR) helps in protecting the junction from high stimulation pressures.

These technologies have been tailored to meet the application requirements. The success of this application will encourage exploring the potential for multi stage fracturing in more complex multi-lateral wells, such as tri-laterals, creating a positive impact on petroleum industry by enhancing production and achieving higher profitability from these wells with potential of reducing the number of wells to be drilled to achieve a desired production rate.
Understanding the Concurrence of Drilling Induced Fractures and Breakouts and Its Implications on Drilling Performance Using a 3D FEM and Field Imaging Data
Authors: AlBahrani Hussain , Morita Nobuo
Published: January 2020

The drilling mud weight window addresses two modes of wellbore rock failure which lie on opposite ends. Breakouts being near the minimum limit and fracturing at the maximum. However, as evidenced by image logs, it's not uncommon to identify breakouts and induced fractures taking place within the same interval. Exploring this interesting phenomenon should lead to better understanding of how the window changes. This should also serve to identify near misses preceding drilling troubles.

In this work, field data are first used for the diagnostics of this phenomenon and to verify the order of occurrence of each mode of failure. Different forms of image logs taken at different time intervals are used for this purpose. Having established the values of relevant variables such as mud properties, rock properties, and wellbore dimensions, a 3D finite element model is then used to quantify the changes in the drilling window as each mode of failure starts to take place.

It is observed that while fluctuations in the bottomhole pressure during the different drilling phases could be a starting point to understand this phenomenon, it's not sufficient. This is especially apparent when considering the size of the window or the various measures taken by modern day drilling practices to maintain the bottomhole pressure within the window. Understanding the order of each failure occurrence and their impact on each other serves to accurately identify the onset of a host of drilling troubles such as lost circulation, poor hole cleaning, and stuck-pipe incidents. This will essentially work to produce a first attempt at estimating the life cycle of the drilling window throughout the different drilling phases with the end result being a dynamic definition of the window. The outcome of this work presents a new perspective through which, different drilling variables can be manipulated to eliminate the onset of drilling troubles. Based on this, it can be shown how the allowable mud weight is evolving from its base range as the wellbore begins to deform. The implications of these changes of the drilling window can be reflected on other peripheral variables such as surge and swab tolerance and allowable equivalent circulating density.

The results of the model can be used to insure more efficient employment of bottomhole pressure maintenance techniques such as managed pressure drilling. Also, in a system where the required real-time data gathering equipment is available, the model provides a path towards automating the responses to the constantly changing environment downhole.
A New Method to Quantify Interwell Connectivity Using Performance Data and Intelligence Algorithm
Authors: Liu Xue , Qu Xiangyun , Jiang Ming , Huang Jing , Chen Cunliang
Published: January 2020

Interwell dynamic connectivity is one of the important indicators for development evaluation of water flooding oilfields. It is widely used in identification of dominant channels, judgement of fracture sealing and evaluation of development effect. The traditional capacitance-resistance model (CRM) can not consider the change of start-up pressure gradient and liquid production index of heavy oil reservoir. For better quantifying the interwell connectivity of heavy oil reservoir, a new method is proposed using performance data and intelligence algorithm.

Experiments show that there is a starting pressure gradient in heavy oil flow. The pseudo-start pressure gradient model is used to characterize this phenomenon. On this basis, the fluid production model of heavy oil reservoir is deduced and established. The results show that the liquid yield index increases with the increase of water content, which is not a constant. And then, a time constant function is constructed to characterize the lag and attenuation of water flooding signals in formation propagation. By substituting the production model and the time constant function into the equation of material balance, a new model is established by difference method. The solution of the new model is transformed into an optimization problem by using the least squares principle. And the quantitative connectivity evaluation is obtained by using frog leaping algorithm.

The new model has been applied in many oilfields. Compared with the single-well dynamic analysis, the accuracy of the new model is very high, but the spent time is less than half of the single-well dynamic analysis. In addition, the paper presents a case study to compare findings from the results of the new model and the use of interwell tracer and interference well testing. The results obtained from this paper shows good agreement with the results obtained from interwell tracer or interference well testing. However, compared with the tracer test or interference well testing, the new method can save a lot of money. In summary, this paper is not only feasible, but also saves a lot of time and money.

The new method considers not only the starting pressure gradient of heavy oil, but also the change of liquid production index. It is an effective method for evaluating injection-production connectivity.
Virtual Metering and Allocation using Machine Learning Algorithms
Authors: Sanzo' Simona , Montini Marco , Cadei Luca , Giuliani Marco , Bianco Amalia
Published: January 2020

In this paper a machine learning algorithm based on neural networks is proposed. The aim is to test a model for multiphase flow rates estimation, taking into consideration the process parameters and the performance of the installed equipment. This model can work in parallel with the Multiphase Flow Meter (MPFM) measurements or acts as a back-up when it fails or it is not present.

The model mainly consists in a multilayer feed-forward neural network, suitable for non-linear regression problems such as the one here considered. The model solution takes a set of reservoir and process parameters as inputs and returns a set of fluid flow information as outputs. The model is trained using actual well test data from producing wells. Generalization and network complexity are regulated using cross-validation. In addition, the mean square error is used as the performance function for training the feed-forward neural network.

The predictive capabilities of the neural network for estimating oil and gas flow rates in multiphase production wells have been assessed against field measurements collected from several production wells operating in west Africa. The developed machine learning model shows promising results and a high level of accuracy, with predicted output very close to the actual MPFM measurements for oil and gas flow rates for specific data considered in the present analyses. Thus, the model can be applied to predict multiphase flow rates in different wells and acts as a back-up when MPFM fails or is not present. The great advantage provided by this model is its inherent simplicity and the small computational time taken to provide an output. Therefore, it can also be thought as a valid alternative to virtual flow metering techniques that are based on physical models and are highly dependent on variables with a high degree of uncertainty (e.g. fluid properties).

This work presents a promisingapproach for virtual metering technique. The methodology has possible application in real time monitoring but also in production optimization, production allocation and reservoir management and it is a cheaper alternative with respect to MPFM, reducing in this way operational and maintenance costs.