bluuebunny/crossref_metadata_2025 huggingface dataset:
Decision Analysis Approach to Valuing Integrated Drilling Operations in the North Sea
Authors: Strasunskas Darijus , Rajaieyamchee Mohammad A.
Published: July 2010

Recently, the petroleum industry has capitalized on remarkable information and collaboration technologies that bring vast amount of real-time data to the decision-makers. The goal is to improve their decision-making processes by integrating technology, people, work processes, and organizations. However, complexity of drilling operations and investment costs put industry in quest for a feasible method to valuate benefits. The prevailing evaluation methods are usually restricted to qualitative approaches, and thus are inefficient as decision aids. The paper presents a decision analytic approach to quantitative valuation of integrated operations.

The proposed valuation method is illustrated by a case from improving decisions’ quality in drilling operations in the North Sea. Improving the quality of operational decisions requires the drilling team to have access to the relevant information in a timely manner. The relevant information needs to be filtered, aggregated, and fused into decisions; and correspondingly represented to the decision-maker. Availability of new information allows making new decisions, and changing work processes. Adoption of a new tool, conformance to a new work process and trust in aggregated and shared information are typically critical success factors. The method is designed to qualitatively analyze changes in intangible capital and assess technology adoption under conditions of operational and economical uncertainties.

The method accounts for information quality improvements and related uncertainties management. In turn, decision analytical part of the method provides a means to relate observable improvements in Key Performance Indicators (KPIs) and uncertainties. Operational decisions are formalized using influence diagram, a.k.a. Bayesian decision network.

Implementation of digital fields and integrated operations is technologically and organizationally challenging. The functional steps of the established methodology and the decision analytic approach are significant contributions to understanding the quantitative value of these projects.
How an Enhanced HSEQ Management Leads to a More Internationally Mobile Workforce
Authors: van der Ende Jean-Paul , Ammous Nejib
Published: July 2010

Tunisia is an area of growing Oil and Gas activity. A number of National Oil Companies are active within Tunisia. This paper focuses specifically upon SEREPT, which has its head office in Tunis and its main operating base in Sfax. It has operations in the Gulf of Gabes (Offshore platform complex) and 2 smaller production sites in the West of the country, near the border with Algeria.

SEREPT was founded almost 80 years ago, originally focussing on exploration. In the 90’s it was operated by Elf Aquitaine (then Arco and Preussag), but since 2003 it is in a Joint Venture with the Tunisian ETAP (Entreprise Tunisienne d’Activites Petrolieres) and the Austrian OMV. Only within the last decade has HSEQ management become an integral way of doing things. SEREPT aligned with the OMV E&P HSEQ management systems, supported by ETAP, bringing about an enhancement in HSEQ management.

Improved HSEQ performance has been visible within SEREPT as evidenced through upward trends in achievement of HSEQ Objectives and overall HSEQ competencies in the workforce. Actual SEREPT HSEQ statistics since 2005 demonstrate this. This enhancement is a double edged sword in that it has led to an improvement in HSEQ performance for the company and HSE competence of its personnel. The adverse affect of this is the ongoing exodus of experienced and qualified local personnel to international operators. This effect has then created an HSEQ vacuum resulting in a gradual dip in HSEQ performance. So, the benefits of HSEQ improvement have had a knock-on effect for SEREPT and this need to be addressed. This paper will be supported by actual studies undertaken by third parties that have empirically demonstrated an improvement in HSEQ performance over the years, but also the emigration of key personnel, causing an HSEQ vacuum. It will also provide some suggestions as to how this problem may be reversed.
Analysis of Pressure Transient Date With Account of Influence Gas-liquid Compositions Flow In Inclined-directed Wells
Authors: Karnauhov M. L.
Published: July 2010

For regulation and management of development process of oil and gas fields on them various kinds of researches are continuously spent. In a complex of these researches the main things are well testing, which performance the periodic stop of well and carrying out of various regimes of it working and record the pressure build–up curves is required.

At the same time it is essential to raise quality of layer researches and reliability of the information on storage development of oil or gas. It would be possible at performance of continuous gauging well bore pressure in working wells. Complexity of carrying out of such researches is connected with necessity of performance of gauging for wells equipped pump installations.

There are various means of registration well bore pressure (remote gauges of pressure, temperatures, etc.). However such means basically are focused on an assessment of works of deep pumps and are not used as sources of the information
Laboratory Investigation on Gelation Behavior of Xanthan Crosslinked With Borate Intended to Combat Lost Circulation
Authors: Mokhtari Mehdi , Ozbayoglu Even M.
Published: July 2010

Crosslinked polymer gels have been extensively used in upstream petroleum industry for water shut-off, profile modification and hydraulic fracturing. The successful history of those applications has led to opening of a new frontier for solving one of the most severe and costly drilling problems known as lost circulation. Xanthan chains can be crosslinked by borate ions released from borax in appropriate pH conditions and consequently convert to a three-dimensional gel structure that can block thief zones.

Steady shear viscometry method was applied in which the gel system was under constant shear rate while apparent viscosity had been recording. Apparent viscosity is almost constant up to initial gelation time in which viscosity starts growing up. Initial and final gelation times, initial and final viscosities are parameters that can describe the behavior of a gel system and are reported in this paper. The effects of concentrations of xanthan blended with borax, a pH-controller, and magnesium chloride as well as mixing time, shear history and temperature were investigated. Moreover empirical models are suggested for prediction of initial and final gelation times/viscosities as a function of the above-mentioned variables.

Although the initial gelation time decreases when mixing periods increases, the summation of those is constant. In other words, the reaction causing gelation cannot be postponed by mixing. This is also true when the gel is at rest. On the other hand, it was observed that gels with high-shear rate history demonstrate similar initial gelation time as gels under 3 rpm steady shear. Moreover this low shear rate was found to not interfere in initial gelation time. Temperature and pH-controller reduce the time required for initiation of gelation. Magnesium chloride reduces the viscosity. Consequently the final gel is weaker and occurs in a longer time. Xanthan blended with borax contributes to the system mainly by increasing the viscosity. Finally the empirical models can be used to manage lost circulation treatment job. They help to have enough time to pump the pill with a known viscosity and wait enough on a gel with a desired quality.
Underbalanced Drilling Technology adds Reserves and Enhances Ultimate Recovery
Authors: Babajan Salar , Qutob Hani
Published: July 2010

The current world petroleum industry situation is that:➢Exploration is difficult and costs are increasing.➢The majority of hydrocarbons being exploited today are found in existing pressure depleted or complex and lower quality reservoirs➢Current oil prices are up-and-down

Thus, world circumstances have forced today’s petroleum industry to rethink both its operating methods and technologies aiming at improving recovery and reducing cost. It is believed that adoption of new technologies is the most important factor in adding reserves, enhancing recovery, reducing cost and increasing revenue. Underbalanced drilling technology is now seen as the way to achieve these objectives.
Realising Opportunities Using Integrated Production Modelling in Occidental of Sultanate of Oman
Authors: Al Lawati M.. , Al Salmi A.. , Al Kharusi A.. , Al Hajri S.. , Al Siyabi I..
Published: July 2010

Integrated Production Model IPM is a numerical simulation model using rigorous physics to describe the behavior of an entire production system and produce optimization soulutions of any operated field by integrating the reservoir models, well models and the surface network model.

Integrated production model using IPM suite (Petex) was implemented in field X mainly operated with gas lifted production system, which is located in the North of Sultanate of Oman. This is a distinguished, proactive and creative process of searching and realizing opportunities that are occuring in daily life of a producing gas lift field.

The process has included four phases. First phase was characterizing, predicting phase behavior and dynamic fluid properties of reservoir fluid. Second phase was building field reservoir models in MBAL using material balance simulation. This helps predicting reservoir pressure and forecasting senarios. Third phase was modeling all wells in Prosper including all subsurface mechanical components and generate the vertical lift curves to examine production performance of the well at different welltest and reservoir pressure conditions. The last phase was building surface network model GAP and link that to all the reservoirs and wells models. At this point system response was validated and calibrated to represent actual field status.

Going through the process of integrated production system modeling resulted in an increase of 8% of total field production by individual wells optimization. In addition more than 25% of gas lifted gas was saved through optimum distribution of lifting gas among the producers.
El Borma - Bright Water®: A Tertiary Method for Enhanced Oil Recovery for a Mature Field
Authors: Ghaddab F.. , Kaddour K.. , Tesconi M.. , Brancolini A.. , Carniani C.. , Galli G..
Published: July 2010

For some years SITEP and Eni have started to evaluate certain tertiary methods of enhaced oil recovery for El Borma, a mature tunisian field. A pilot project based on the application of a commercial chemical product called "BRIGHT WATER®" (BW), a trademark of Tiorco-Nalco, was chosen to verify on a real case its applicability and efficiency. The technology aims at the improvement of the oil recovery and at the reduction of the water production. This methodology is applied for oil mature fields, that are subjected to the water injection and that are presenting a heterogeneous reservoir with contrast of permeability. This paper describes the work performed to design a field test of such a technique in El Borma, with the twofold purpose to achieve the highest probability of success and gather as much information as possible to use in future applications. The project went through four phases: 1. Selection of one injector well and one producer; 2. Program of monitoring to verify the connection between the injector and the producer (injection of a tracer to determine the arrival time and simulation on a numerical model); 3. Injection of the polymerics and monitoring; 4. Application on the other zones of the field, in case of the success of the method. The first three phases were completed at the beginning of 2010. This work also describes the workflow which will be established to follow the improvements of the oil production.
Flexural Distortion Analysis of the Mandrel in an Orienting Rotary Steerable Drilling Tool
Authors: Jiang Shan
Published: July 2010

The design of orienting rotary steerable drilling tools needs to take both the location of the floating support points and flexural distortion of the mandrel into account. With consideration of the eccentric displacement and bias of offset components in such a biasing apparatus, a comprehensive mechanical model has been proposed in this paper to determine key parameters and to guide the design of orienting rotary steerable drilling tool. It is assumed this mathematical model that 1) the eccentric force is concentrated at one point of a mandrel; 2) one end of the mandrel is hinged; and 3) the other end may slide along the axial direction on the support point. The relationship between flexural distortion curve and the axial offsetting (λ) of a mandrel can then be found. The proposed model and the analysis can be used to guide the design of orienting rotary steerable drilling tools.
Establishment of a Sand Production Prediction Model for Inclined Casing Perforated Well
Authors: Xie Shuangxi , Yiwei Ren , Zhousheng Chen
Published: July 2010

Referring to the casing perforated wells and based on linear-elastic theory, the stress around borehole and perforations of deviated well is analyzed and the influence of stress distribution around borehole and perforations is also fully considered. In the paper, the conception of two formation stability coefficients respectively based on Mohr-Coulomb yield criterion and Drucker-Prager yield criterion is presented. Stress around perforations and Drucker-Prager yield criterion are used to establish a sand production prediction model and prediction software was programmed. Finally, the sand production is predicted for the well W1 by the model and the predicted result is almost identical with realistic situation.
Research for Horizontal Well Reasonable Drawdown Pressure of Heavy Oil Reservoir with Bottom Water
Authors: Li Tingli , Ge Lizhen , Zhao Chunming , Yang Qinghong , Liao Xinwu , Chai Shichao , Qin Wei , Xu Yuxia , Xiao Kun , Bie Xuwei
Published: July 2010

In this paper we detail the work done in rearch for horizontal well reasonable drawdown pressure of heavy oil reservoir with bottom water based on detailed analysis of the geological, reservoir, production history, horizontal well data and production conditions with the intent to enhance rate and recovery efficiency in a heavy oil reservoir with bottom water. We study the geological, reservoir, production history and horizontal well data relate to optimizing horizontal well reasonable pressure drawdown in a heavy oil reservoir with bottom water, like reservoir thickness, horizontal well standoff over oil water contact, honrizontal section length, barriers distribution and viscosity in-place oil. This paper breaks up the past development idea of controlling horizontal well drawdown pressure to delay bottom water conning, and a new theory to high efficiency develop bottom water reservoir is present. This new development theory comes from geology & reservoir and takes production conditions on sea into account, has strong base of theory and practicability.

A combination of geological, reservoir and production history is considered to optimize horizontal well pressure drawdown. Through the work done we are able to identify the reasonable pressure drawdown with every horizontal well including on production and planning. And we are able to identify how much these factors affect optimizing horizontal well pressure drawdown. There are 27 horizontal wells to develop heavy oil reservoir with bottom water at QHD32-6 Oilfield, and next step more horizontal wells will drilled. Some horizontal wells produce poorly because bottom water coning quickly, these wells obtain successful production after enlarging drawdown pressure and accumulative oil production exceed those wells with small drawdown pressure to delay bottom water conning.The rate and recovery efficiency in QHD32-6 Oilfield have been increased largely after this pressure drawdown optimization.

The paper details techniques for pressure drawdown optimization in heavy oil reservoir with bottom water, and indicates high efficiency recovery by horizontal wells in heavy oil reservoir with bottom water is obtainable. This development idea has been applied to several fields at Bohai bay including QHD32-6, CFD11-1, SZ36-1 and CB. Producing practice have testified that high recovery rate for horizontal well of heavy oil reservoir with bottom water is very successful.
An Effective Experience on Reducing the Power Consumption and Produced Water Drainage of Boxi Oilfields
Authors: Junxiong Yu , Zhehua Wen , Liang Geng
Published: July 2010

Part of the produced water of Boxi oilfields was separated from the produced fluid in the central platform to be treated, reinjected and drained, and the remained fluid was piped to the terminal onshore, then the remained produced water was treated and drained onshore. The amount of produced water drained onshore was getting more and more, and a target to reduce the amount of produced water drained, especially onshore, was set to meet the improvement on the environmental protection policy of the government.

In order to reduce the amount of produced water treated and drained onshore and to reduce piping energy consumption, by means of improving the capacities of the separation, treatment and reinjection offshore, most of the produced water in the main production platform was separated from the produced fluid and treated and reinjected through updating the process system in the crowded platform by means of gas and fluid separation by GLCC etc; and the efficiency of produced water treatment has been improved through updating the process system onshore and in the central platform.

The amount of produced water drained onshore was cut by more than 60%. The target to reduce the amount of produced water drained onshore was reached, and the piping energy consumption has been reduced accordingly.

It is an innovation in Bohai Bay to use GLCC to separate gas and fluid in the process system. The job has given an example of sustainable development for the oilfields in their later stage in Bohai Bay.
Pay Zone Protection during Drilling in Offshore Oilfield Producing with High Porosity, High Permeability and Low Pore Pressure
Authors: Deng Jianming , jianmin Deng , xiaocheng Zhang , wenbo Tang , zili Li , hailong Miao
Published: July 2010

When drilling infill wells in heavy oil oilfields of Bohai Bay after over teen years production, there are three challenges to achieve ideal production rate. The first one is wellbore stability in unconsolidated sandstone formation. The second one is risks of pollution and damage in pay zone with high porosity and high permeability. The third one is risks of mud loss and pollution in lower pressure pay zone after producing many years. CNOOC developed a reasonable technique according to the characteristics of pay zones, experiences of production and drilling. After successful applications, CNOOC formulated a good technique series which consists of membrane forming mud, completion fluid and flow-back in time. Production rate of the fifteen wells drilled achieved or exceeded the production allocation. This achievement is successful experiences to improve oil recovery rate and raise recoverable reserves and production rates.
Lessons Learned from a Well's Sand Control Failure in Bohai Bay
Authors: Chen S. H. , Deng J. M. , Fan B. T. , Li Bin , Xu R. Q.
Published: July 2010

This paper describes sand control failure of a well in Bohai Bay which has experienced four workovers and one acid treatment. This well adopted cased-hole premium screen completion initially, changed to another premium screen completion in the 2nd workover and gravel packed in the 4th workover. An extensive data collection and analysis were performed to relate the cause of sand control failure to reservoir data, formation sand characteristics, sand control method, premium screen sizing and so forth. Comparison between targeted well and offset wells has also been conducted to evaluate which kinds of sand control methods are appropriate for the given formation. A number of design and operational guidelines have been suggested for a suitable completion method.
Prediction of Hole Cleaning Efficiency Using a Simple, User Friendly and Better Performing Simulation Model
Authors: Qahtani Abdullah M. , Amanullah Md.
Published: July 2010

The effective removal of drill cuttings from the wellbore is one of the key factors to avoid different drilling problems such as poor ROP, associated cuttings bed formation in the presence of weak mudcakes, embedded cuttings bed formation in the presence of poor quality mudcakes, creation of hole pack-off and pipe sticking problems, significant change in mud properties, increase in the severity of formation damage potential of drilling muds, etc. Poor hole cleaning may also trigger induced loss of circulation, borehole instability, kicks, blowout and other borehole problems due to the direct or indirect consequences of improper hole cleaning. Therefore, an accurate and reliable prediction of hole cleaning efficiency of drilling mud in different drilling condition is an inseparable part of a safe and economic drilling operation. An improved prediction tool could provide the necessary guidelines to take appropriate measures while drilling to avoid drill cuttings associated borehole problems. This paper describes a simple, user friendly and more reliable simulation model to predict the hole cleaning efficiency of drilling mud in different borehole conditions using some critical parameters associated with drilling mud, hole geometry, subsurface condition, and the cuttings properties.
Ensemble Methods for Reservoir Life-Cycle Optimization and Well Placement
Authors: Leeuwenburgh Olwijn , Egberts Paul J. , Abbink Oscar A.
Published: July 2010

Several simple examples are presented that demonstrate the application of an ensemble-based method to production optimization. In particular, some practical aspects of the method such as ensemble size, perturbation, regularization and smoothing, and robust gradient estimation are discussed by comparison with an adjoint approach. The controls in the presented examples are inflow control valve settings for fixed time intervals or well position. We find that the performance of the method is clearly affected by the correlation time scale that is assumed for the controls, as reflected both by the quality of the gradient estimation and the subsequent optimization. The well placement optimization problem is studied for two cases: one is a homogenous reservoir with a sealing fault, and the other a non-homogeneous case. The ensemble optimization method is found to work well for both these simple well placement problems.
An Overview of Geomechanical Engineering Aspects of Tight Gas Sand Developments
Authors: Addis M. A. , Yassir N.
Published: July 2010

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

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

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

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

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

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

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

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

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

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

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

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.
Analysis of Capillary Pressure and Relative Permeability Effects on the Productivity of Naturally Fractured Gas-Condensate Reservoirs
Authors: Al Ghamdi Bander N. , Ayala Luis F.
Published: July 2010

Productivity of gas-condensate reservoirs can become severely impaired due to the appearance of condensate near the production channels, which in turn reduces the overall flow of fluids to the surface. The deliverability of gas-condensate reservoirs is controlled by transport properties, which include capillary pressure and relative permeabilities between the fluids in a pore-scale. In this work, the productivity of naturally fractured gas-condensate reservoirs is studied using a compositional simulation model that examines the effects of capillary pressure and relative permeability values on the recovery of gas-condensate fluids. A compositional simulation model was utilized for the evaluation of the influence of fluid characteristics on the severity of condensate coating while assigning tight matrix permeability of 0.001 md. The study utilized different reservoir fluid composition found within the gas-condensate spectrum and examined the performance behavior with and without capillary pressure effects. The parametric study showed that for the conditions under examination, capillary pressures did not significantly affect performance in terms of fluid distribution, movement, condensate evolution, and recovery. Relative permeability effects showed dependency on condensate content of the reservoir and extent of reservoir condensation