bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Overview of Geomechanical Engineering Aspects of Tight Gas Sand Developments
Authors: Addis M. A. , Yassir N. 
Published: July 2010

Abstract
Tight gas sand exploration and development is a key focus as markets around the world exploit local resources for natural gas. Tight gas sands have matrix permeabilities in the micro-Darcy range and low porosities (typically ~5%). Commercial production is possible from these reservoirs when they have a conductive natural fracture system, and when they are stimulated by hydraulic fractures. However, both the formation matrix and the natural fracture systems can be stress-sensitive, i.e. they close during depletion, reducing the gross permeabilities which pose numerous challenges to establishing sustained economic flow rates. Geomechanical engineering is central to the development of these tight gas resources: Economic flow rates and commerciality of the field developments can only be achieved by stimulation, through fracturing and dilation of the reservoir formations; imposing a ‘man-made’ permeability network on the geological system.
This paper discusses geomechanical considerations of wellbore orientation, in-situ stress systems, and connectivity between hydraulic fractures with the natural fracture system, for single and multi-staged fracturing.
A major consideration during field development of tight gas sands is the stress evolution accompanying drawdown and depletion. It is now well established that reservoir pressure changes have an effect on both the stress magnitudes and the stress directions in the sub-surface. Two major consequences of the stress changes are addressed: Well placement: Understanding the stress evolution accompanying depletion is central to optimally plan the well locations, infill locations, and hydraulic fracture treatments. Stress changes result in fracture re-orientation following the re-completion, and an increase in the productivity and ultimate recovery from these wells. In addition, optimally placed new infill wells may become more productive than the initial wells as a result of improved connectivity with open fracture systems.Sweet spot enlargement: Greater production and ultimate recovery is commonly observed where the fracture system is "relaxed" or "critically stressed". As the stresses change accompanying depletion, so can the sweet spots, with potentially negative impact on development. Geomechanical engineering can be used in field development planning to define depletion strategies which produce an optimum stress evolution in the reservoir to open up these tight formations, by enhancing the conductivity of the natural fracture system. Thus, the productive sweet spots provided by nature may be enlarged to increase the available gas resources and higher ultimate recoveries, by increasing the area available for commercial development.
The geomechanical engineering aspects of tight gas sands are discussed, highlighting some potential areas where tight gas sand developments can be optimised.
Post-Stimulation Results and Analysis of Highly Successful Multi-Stage Acid Fracturing Campaign Performed in Tight Gas Carbonate Formations in Saudi Arabia
Authors: Franco C. A. , Solares J. R. , Al-Shammari N. S. , Al-Harbi M. M. , Alabbad E. A. , Bukovac T. 
Published: July 2010

Abstract
The number of horizontal gas-condensate producers drilled in the Ghawar field has consistently increased through the years as part of Saudi Aramco’s strategy to maximize reserves recovery and production from tight gas-bearing carbonate reservoirs. A number of under-performing or severely damaged producers require stimulation to achieve production targets. Consequently, such wells have been completed with fit-for-purpose completions designed to perform effective multi-stage massive fracturing treatments along the entire drilled horizontal section. A number of wells have been successfully stimulated utilizing this approach, along with other technologies such as bio-degradable fiber diverting agents used to enhance fluid leakoff control in naturally fractured sections of the reservoir exhibiting high permeability contrast.
This paper describes the outstanding post-stimulation results achieved from the application of multi-stage fracturing technology in several gas producers, and shares details of a comprehensive technical study conducted to ascertain the effectiveness of the stimulation treatments. Lessons learned throughout the stimulation operations are also highlighted, which will be used to further optimize future treatments and to prioritize candidates.
Successful Selective Stimulation of Open Hole Dual Lateral Gas-Condensate Producers with a Coiled Tubing, Hydra Jetting Tool and New Isolation Sleeve in Saudi Arabia
Authors: Garzon Francisco , Franco Carlos , Al-Saeed Hussain A. , Al-Omair Wael M. , Ginest Noel H. , Sierra Leopoldo , Surjaatmadja Jim , Izquierdo Guillermo 
Published: July 2010

Abstract
Drilling open hole multilateral (MLT) gas wells in carbonate reservoirs designed to maximize reservoir contact and reserve recovery is a common practice in Saudi Arabia. A significant number of wells have been completed using this approach in the past few years.
Stimulation of the MLT gas wells is often required either to remove induced damage from drilling operations or to enhance well productivity. The selective accessing and stimulating of these open hole completed wells is a challenge when using conventional technologies.
Several MLT Khuff-C wells with horizontal sections exceeding 3,000 ft were successfully accessed and selectively stimulated. This paper describes the accessing and stimulation operations performed with a coiled tubing (CT), hydra jetting tool and a new isolation sleeve used for the first time in the world to achieve effective stimulation. The excellent post-treatment results achieved are also presented and discussed.
Innovative Approach to Stimulate Horizontal Gas Well Using DTS Technology Combined with Coiled Tubing in Saudi Arabia
Authors: Garzon Francisco , Solares J. Ricardo , Amorocho Jose Ricardo , Al-Mulhim Abdulmohsin , Kharrat Wassim , Hamed-Naji Iyad , Brown George , Noya Vidal 
Published: July 2010

Abstract
The objective of most acid stimulation treatments in Saudi Arabia’s Khuff carbonate formations is to remove drilling induced damage and achieve maximum well productivity. Open hole and multilateral completed wells, present several challenges that prevent an optimum intervention and placement of fluids with coiled tubing (CT). Traditional stimulation practices of these types of producers usually involve spotting fluid systems comprising multiple stages of pre-flushes, acid, and chemical diverting agents along the horizontal section of a well without adequate control over treating fluids’ placement and displacement.
An innovative approach, combining fiber optic enabled coiled tubing (FOECT) and distributed temperature survey (DTS) recorded data with reservoir data to selectively place stimulation fluids in targeted formation sections, was successfully field tested in a dual-lateral horizontal gas well completed open hole in Saudi Arabia.
This paper describes the job design, the operations performed to access the desired lateral, and the stimulation treatment performed combining the two technologies. Details on how the DTS technology was used to identify thief zones during the actual stimulation treatment, and how the placement of treatment fluids was optimized along the horizontal section, are also provided. The successful implementation of the first field trial has provided a strong incentive to utilize a similar approach in other gas producers currently scheduled.
Remote Operations at Shell – A Case History From the Giant NAM Groningen Gas Field in the Netherlands
Authors: Douwes Brugt , van Meijeren Wim 
Published: July 2010

Abstract
In the last two decades Shell has been working to simplify and automate field operations processes and sub-processes in its assets throughout the world. This is driven by the need to develop competitive and cost-efficient technical solutions that increase safety and reliability of operations, especially in remote and/or harsh environments.
Remotely starting up and shutting down certain pieces of equipment was already standard practice in the industry since decades, introduced in gas fired furnaces, heaters, and boilers. Nowadays, automation has extended to sensitive equipment and complete processing units.
This paper looks at the level of automation and degree of remote operations achieved in the operation of the giant NAM Groningen Gas Field, in the north of The Netherlands. NAM is a joint venture between Shell and Exxon, operated by Shell. After an extensive redevelopment project, with the addition of compressors, more than 300 wells, previously distributed over more than 25 locally operated production facilities, are now linked up and operated remotely from one central control room by two operators. The production facilities are now normally unmanned, and only visited for repairs and/or scheduled maintenance. NAM Groningen demonstrates a technically advanced solution that minimizes HSE and risk exposure, standardizes operations, and reduces resources required to manage one of the largest gas fields in all of Europe.
Using some of the most advanced technologies available in the industry, Shell has applied such a high degree of automation to NAM’s Groningen gas field, that each of the production facilities can be ramped up from zero flow to some 25 million Nm3/d in only one hour – all remotely.
Three-Dimensional Inversion of Borehole Gravity Measurements for Reservoir Fluid Monitoring
Authors: Hadj-Sassi Khaled , Donadille Jean-Marc 
Published: July 2010

Abstract
The fluids in the reservoir are redistributed in response to pressure gradients caused by hydrocarbon production, which is often coupled with injection of water or gas. It is known from density logging that the density of pore fluids is an important physical property useful in inferring oil, water, or gas saturation in a rock. Thanks to the density difference of the different phases, the borehole gravity measurement is a candidate for tracking the movement of fluids hundreds of feet away from wellbores. Such data are measured in time lapse to provide the three-dimensional distribution of density changes in time through an inversion procedure.
Because gravity is a potential field, the inversion of borehole gravity data is inherently non-unique. The decrease of the sensitivity to the recorded data away from the measurement location is also a challenge for the inversion problem. The approach implemented in this work uses an iterative algorithm that minimizes a global objective function. The objective function includes the data misfit functional and a three-dimensional regularization that is needed to constrain the inversion to reasonable solutions. A weighting function based on the distance between each gravity source and the recording instrument is introduced to help mitigate the geometric decay of gravity kernels with distance from the sensor. Synthetic inversions are presented that indicate borehole gravity can be instrumental in detecting and monitoring a large water front. This study also points out the optimal conditions for using borehole gravity for fluid front monitoring, in terms of number of wells, relative well positions to the target, vertical sampling, and measurement accuracy.
Practical Application of Surface-Wave Methods to Estimate a Near-Surface Velocity Model at Spring Coulee
Authors: Al Dulaijan Khaled , Stewart Robert R. 
Published: July 2010

Abstract
Variations in the thicknesses and velocities of near-surface layers can cause serious problems for seismic reflection imaging of the deeper subsurface. Static corrections, calculated from near-surface velocity models, are used to remove the effects of the variable near surface. In this paper, near-surface layers are characterized using a method known as Multi-Channel Analysis of Surface Waves (MASW). This method is mainly used for geotechnical engineering applications and is based on the dispersion properties of Rayleigh-waves. Here, it will be used for calculating S-wave statics for a site located at Spring Coulee, Alberta. The results will be compared to those generated by applying Generalized Linear Inversion (GLI) of first arrival times; a widely used and proven method for obtaining near-surface velocity models for both P- and S-waves.
In the case of an isotropic homogeneous half space, Rayleigh-waves are non-dispersive with different frequencies traveling at the same velocity. In a real layered earth, Rayleigh-waves are dispersive (the velocity is dependent on frequency) with multiple modes. The phase velocity of surface waves traveling through a layered earth model is a function of the frequency and four earth parameters; P-wave velocity, S-wave velocity, density, and the layer thickness. The Rayleigh-wave phase velocity is most sensitive to the S-wave velocity and the layer thickness. From an initial model, Rayleigh-wave phase velocities of different frequencies (dispersion curves) are calculated, and then compared to the measured dispersion curves. Then the initial model is updated until some acceptable agreement with the measured dispersion curves is reached.
In the Spring Coulee analysis area, the S-wave near-surface models, obtained by the GLI method, had different velocity layering and base of weathering from those of the Pwaves. The MASW S-wave velocity model correlated well to the GLI model. For converted wave PS sections, the improvement in the quality of reflection events after applying S-wave statics from the MASW model is similar to the event quality after application of the S-wave statics from the GLI refraction model. Identifying and picking S-wave first arrivals manually is a difficult and time consuming process. Unfortunately, automatic picking programs do not work well for S-wave refractions. Confusing S-waves with Rayleigh-waves is also a problem. Picking fundamental modes dispersion curves of Rayleigh-waves is easy and fast. Therefore, the MASW method is a potential alternative to the GLI method for modeling S-wave velocities of the near surface.
Pressure Transient Analysis: Characterizing the Reservoir and Much More
Authors: Al-Harbi Badr M. , Bin Akresh Saud A. , Al-Ajaji Abdulaziz A. , Pinilla Forero Edgar J. 
Published: July 2010

Abstract
The development stage of any new field requires careful and full integration of all available data to ensure the robustness and flexibility of the development plans. One major source of information that adds a wealth of knowledge and reduces the number of uncertain variables in any field development is Pressure Transient Analysis (PTA). When used properly, this tool can provide accurate information about reservoir heterogeneities and well parameters such as permeability thickness, reservoir features, skin, and productivity indices.
This paper presents a comprehensive study where pressure transient analysis played a key role in detecting various reservoir features at the early phase of a field development. It further shares cases where pressure transient analysis confirmed good pressure communication across a layer that was thought of as a very tight layer. Also, the study participated in building a new realization of faults existence in the field. Many faults were removed from the field geological model based on insights from PTA and some other dynamic data. Some other case studies are included showing the full power of Pressure Transient Analysis which added significant value to reservoir properties definition. Furthermore, this paper will shed light on the use of pressure transient analysis for fluid characterization proposes.
The studied reservoir has a very complex nature in terms of rock and fluid properties. Both, the rock and fluid vary in the lateral and vertical direction making rock and fluid characterization a very challenging task to be completed.
Analysis of vintage and newly acquired well test data of this field played an important role in understanding the reservoir and helped fine-tune the development strategy. Integration of different data proved to be, yet again, a best practice to understand reservoirs and act accordingly
Optimizing Horizontal Well Configurations for Effective Drainage of Thin Oil Zones Overlying Productive Formations under Strong Water Drive
Authors: Fischbuch D.B. , Taibah O.A. , Al-Zahrani T.M. 
Published: July 2010

Abstract
Exploitation of thin oil zones overlying thick, productive carbonate formations poses a unique challenge for reservoir development, particularly with strong water drive. The main challenge is effective oil recovery without excessive water production. Reservoir management considerations addressed in this study include locating current fluid contacts, evaluating geological complexity, assessing vertical permeability contrast, optimizing well configuration (length and vertical placement), utilizing appropriate geo-steering techniques to ensure correct well placement, and optimizing completion design. This paper compares comprehensive reservoir simulation findings with field results for various well configurations for a carbonate reservoir in Saudi Arabia. Preferred wellbore configurations have large reservoir contact with laterals placed at the top of the thin oil zone and wells completed to provide uniform flow contribution along the wellbore. Best practices have been developed for effective oil drainage from thin oil zones overlying thick, permeable carbonate formations under strong water drive.
Automate the Process of Managing Well Logs Data
Authors: Al-Ghamdi Turki A. , Zahdan Ghassan O. , Ali Hussein A. , Nahwi Ibrahim M. 
Published: July 2010

Abstract
The world increase demand for oil over the past years have placed oil & gas companies like Saudi Aramco at forth front to meet market calls by expanding drilling activities. In tail, the well logging services raises calling for improved systematic approach to manage and control the various well log workflow services and the different well logging data types. At the same time, other external challenges make it very difficult to maintain well logging operational activities with existing data management solution and available resources. For that reason and to stay at the competitive edge, Saudi Aramco realized the need to operate in such dynamic environment to develop a Data Services System (DSS) to optimize and streamline the archiving, tracking, quality checking, publishing, and managing of well log data acquisition making it accessible to all Saudi Aramco disciplines.
This data management solution called Data Services System (DSS) that developed by Petris Technology Inc. and designed by Saudi Aramco. DSS provides a simple mechanism for managing well logs data in a continuously changing environment. It is based on generic set of services which are orchestrated to provide a collaborative working environment for field, processing and interpretation well groups. This system has proven its value by allowing the service companies to send well log data directly from their site to Saudi Aramco center without the need of physical media delivery.
Dielectric Response of Carbonate Core-Plugs – Influence of Heterogeneous Rock Properties on Permittivity
Authors: Zhang Tianhua , Ligneul Patrice , Nicot Benjamin , Pairoys Fabrice , Akbar Mahmood 
Published: July 2010

Abstract
Heterogeneities of carbonate core plugs can be assessed by different measurements resulting in different interpretations. In this study, dielectric spectroscopy, NMR, and tracer displacement method performed on the same cores reflect different aspects of heterogeneity related to their own characteristic length scales and physics of the measurements, which complement each other in a multiphysical interpretation.
The complex dielectric permittivity measured on carbonate core samples in the reflection mode in the range of 1 MHz to 1 GHz, exhibits a strong difference between the two extremities of the plugs when turning them upside down. The difference between the two extremities is a result of heterogeneity in the rock plug. It can be due to chemical composition, density, porosity, water saturation, presence of cavities, vugs and micro-fractures, crystalline structure and rock lithology, and, distribution of components inside the rock, which is a complex process need to be fully understand. The dielectric heterogeneity is compared with the NMR porosity profile which, in certain cases, indicates cross section averaged porosity heterogeneities along the core-plug axis and correlated with tracer displacement measurement, which characterizes the pore system hydraulic connection and its related heterogeneity.
To complete this "multiphysics" approach, a numerical forward model of the electromagnetic propagation in the core-plugs was performed, focusing on the effect of artificial vugs at different locations inside the core-plug on the electromagnetic propagation patterns.
From dielectrics and NMR profiles, quantitative heterogeneity indexes are proposed and compared, and correlated with tracer displacement measurement. This results in a better characterization of pore system (such as size, distribution, connectivity). A preliminary carbonate rock model taking into account the pore size effect is developed. The cementation factor is inverted from dielectrics dispersion curve measurements, a good match between inversion and laboratory measurements indicates the importance of pore partitioning in carbonates. These laboratory measurements on core plugs can be applied to well-bore measurements combining for instance Array Dielectric Scanner and NMR downhole tools.
Field Application of Composite Reservoir Model on Non-Unit Mobility Flow
Authors: Al Gahtani Abdallah , Yahaya Anes Usman 
Published: July 2010

Abstract
The fluid flow in porous media has been addressed in literature for obvious reasons. A large portion of petroleum engineering literature was focused on developing solutions for different flow/well models. Composite reservoir model has drawn attention of well testing researchers. The complexity of oil reservoirs in the field make the use of developed models limited. A composite reservoir is made up of two or more regions. Each region has its own rock and fluid properties. A composite system can occur naturally or may be artificially created. Aquifers with two different permeabilities forming two regions, oil and water regions or gas and oil regions with different properties in a reservoir are examples of naturally occurring two-region composite systems. For a well in a radial composite reservoir, the reservoir model usually considered is the radial composite model, in which the well is centered in a circular region of mobility M1 and storativity S1. Beyond this inner zone, the reservoir has mobility M2 and storativity S2. The outer zone mobility may be either higher or lower than that of the inner zone. Field engineers are inclined to use oil flow models for interpreting well tests as long as these wells produce dry. The fluid fractional flow in formation, however, changes as more water encroaches toward the producing well.
This paper presents a study focusing on an important application of the use of analytical solutions of composite reservoir model to evaluate the impact of non-unit mobility flow. This is of paramount importance in fields with big differential of mobilities of oil and water as in this study. This research work is to highlight the significance of consideration of water flow impact in formation before wells start cutting water. The solutions were validated with other semi analytical solution and supported by field data.