bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wellbore Stability analysis in UBD Wells of Iranian fields
Authors: Salehi S. , Hareland G. , Dehkordi K. Khademi 
Published: December 2007

Abstract
Drilling underbalanced is often used to prevent formation damage, avoid lost circulation, and increase rate of penetration. However, it is also risky and may lead to wellbore collapse due to lack of positive support provided by the hydrostratic wellbore fluid column. Hence, the application of underbalanced drilling (UBD) should be evaluated thoroughly through the use of in-situ stresses and rock mechanical properties to estimate under what hydraulic drilling conditions the wellbore is stable.
This paper presents a mechanical wellbore stability analysis for two depleted Iranian fields, named herein as field A and B. Depleted Iranian fractured carbonate fields are suffering from severe wellbore stability problems and lost circulation during overbalanced drilling conditions. The application of UBD in these fields with a pressure less than formation pore pressure brought on new wellbore stability problems like risk of shear failure and collapse of borehole wall. Using good geomechanical model description matching field characteristics in conjunction with rock failure criteria in some cases may lead to a good prediction for avoiding wellbore stability problems and choosing the optimum mud weight window. By analyzing cores, log and triaxial rock mechanical data, an elastoplastic model combined with a finite-explicit code was used in the wellbore stability analysis to estimatimate an optimum Equivalent Circulating Density (ECD) for these fields. Compared to some actual field data it was observed that using an elastoplastic constitutive model would be sufficient to analyze mechanical wellbore stability in these fields.
Pore Network Modeling: Analysis of Pore Size Distribution of Arabian Core Samples
Authors: Dong Hu , Touati Mustafa , Blunt Martin J. 
Published: December 2007

Abstract
We use X-ray microtomography (micro-CT) to image rock cuttings of poorly consolidated sandstone and vuggy carbonate from Saudi Arabian oil and gas fields. The cuttings are a few mm across and are imaged to a resolution between 3 and 12 microns. The details of the three-dimensional pore space can be clearly seen. A maximal ball algorithm is used to extract a topologically equivalent pore network: the largest inscribed spheres in the pore space represent pores, with throats representing the connections between them. The results are validated through comparison with networks derived by a different method from idealized sphere packings and Fontainebleau sandstone.
The aim of this work is to input the models into pore-scale network models to predict macroscopic properties such as relative permeability and capillary pressure. This acts as a valuable complement to special core analysis, enabling predictions of properties – such as three-phase relative permeabilities and the impact of wettability trends – outside the range of parameters probed experimentally. Furthermore, using microtomography, rock cuttings can be analyzed that are too small for conventional core flood experiments.
Accelerating Technical Competency Development to Meet Future Challenges: The Saudi Aramco Approach
Authors: Solares J. Ricardo 
Published: December 2007

Abstract
Saudi Aramco, as most other major oil companies around the world, will face a looming crisis when a large number of experienced and highly qualified engineer and earth sciences professionals are expected to retire and exit the oil industry within the next five years. In anticipation of this occurrence, the company has embarked on a number of initiatives all aimed at accelerating the development of technical competencies in young professionals to ensure a smooth "change of the guard" transition, and meet the ever-growing challenges of the future when implementation of highly complex technology will require well developed skills.
To confront these significant challenges, Saudi Aramco has developed and implemented a multi-strategy approach combining fit for purpose technical courses designed to reduce specific technical competency gaps, practical work experiences, formalized mentoring programs, special cross-training assignments, specialist skills development programs, knowledge sharing systems and others. Detailed individual long-term technical development plans are prepared for all technical personnel with clearly defined targets and expectations, which are then implemented and continually monitored to ascertain progress and make adjustments whenever required.
This paper elaborates on the Saudi Aramco approach, discusses results achieved to date, and shares ongoing way forward plans to strengthen the program and achieve its objectives.
The successful implementation of this effort will help the company mitigate the impact of losing experienced technical personnel to retirement, and will ensure that new generations are fully prepared to face a bright and challenging future.
Improving Formation Strength Tests and Their Interpretation
Authors: van Oort Eric , Vargo Richard 
Published: December 2007

AbstractVerifying pressure integrity of a casing string and the adjacent formation is an important requirement during drilling of a well. Crucial decisions on mud weight, kick tolerance, and the setting depth of the next casing string are based on the outcome of formation strength tests (FST) such as leak-off tests (LOT) or formation integrity tests (FIT). Moreover, government regulations usually require that a minimum integrity is guaranteed before a well may be deepened.Yet the majority of FSTs and their interpretation currently carried out in the field can only be characterized as inadequate. Commonly, FSTs lack quality and accuracy due to (in)sensitivity in the hydraulic system to subtle pressure effects in the wellbore, use of highly compressible synthetic or oil muds, non-linear thermal profiles, poorly-understood formation stress and strength behavior, or simply by poor data capturing (e.g. by hand-generated plots). This may have a significant negative impact on the drilling operation. For instance, when mud weight windows are incorrectly assessed after testing, lost circulation or well control problems may ensue on wells with tight drilling margins.Here, we highlight several of the problems underlying current FSTs and their interpretation, illustrating them with actual field examples (such as the discrepancy often observed between surface readings and downhole pressure-while drilling (PWD) readings obtained while testing), and show how test artifacts can be either avoided or accounted for. A case is made for the use of downhole recorded pressure data to correctly determine casing shoe strength.
Real-Time Digital Interpretation of Subsea Blowout Preventer Tests
Authors: Winters Warren J. , Burns Tim A. , Livesay Ronald B. 
Published: December 2007

Abstract
A computer based method expedites interpretation of pressure data during subsea blowout preventer (BOP) tests. This can reduce the time and cost of current subsea BOP testing practices in a safe and objective manner.
Presently, individual tests can require more than 1 hr. of shut-in time and a complete series of subsea BOP tests may comprise at least 12 individual tests.
The digital method employs computer software to produce an accurate model of the pressure decline behavior relatively early in each test. The model can thus predict if future pressures will stabilize at an acceptable level. With regulatory approval and a reliable method to forecast pressure, the duration of subsea BOP tests can be significantly reduced.
Comparison of the digital method to conventional subsea BOP testing on numerous field trials shows excellent agreement. If implemented the digital method could save hours of valuable critical-path rig time during every series of subsea BOP tests.
Working in concert with regulatory authorities to gain endorsement of this method is integral to the project. Functionality of the software, example results and implementation status are reported.
Application of Global Optimization Methods for History Matching and Probabilistic Forecasting—Case Studies
Authors: Choudhary M. K. , Yoon S. , Ludvigsen B. E. 
Published: December 2007

Abstract
Subsurface uncertainties have a major influence on investment decisions in major capital projects. By understanding and quantifying subsurface uncertainties better, investment risks can be reduced and decision quality can be improved. Quantifying subsurface uncertainties for a mature field involves history matching or solving the inverse problem, which is not only difficult but also non-unique in nature. A suite of acceptable history matched models, which have multiple combinations of model parameters, is required to obtain a probabilistic view of the reservoir performance. Once a suite of models that all match history has been obtained, they are calibrated for predicting the future performance and assessment of uncertainty and risk associated with a particular development plan. In this paper, we demonstrate a structured approach to history matching, uncertainty assessment, and probabilistic forecasting for mature assets through application of global optimization methods.
This work involves application of global optimization methods (Evolutionary Strategy and Genetic Algorithm) for history matching, uncertainty assessment, and infill well optimization. Specifically, the process involves re-evaluation of manually history matched models, investigation of the possibility of achieving multiple history matches, and quantification of the impact these results had on the decision process. Furthermore, the study used a workflow to determine P10-P50-P90 outcomes without using response surface (or proxy) methodology.
Results from application of our approach to two mature West African reservoirs are presented here. Both these studies explore various subsurface uncertainties to achieve a probabilistic view of multiple history-matched models and optimization of various development scenarios. The case studies also show how a computer assisted approach coupled with a structured workflow can speed up the forecasting and uncertainty assessment process.
Innovation in Coiled–Tubing Tractor Technology Extends the Accessibility of Coiled Tubing in Horizontal Wells, Allowing Better Possibilities for Well Intervention
Authors: Al Omari Mazen , Plessing Hans 
Published: December 2007

Abstract
Recent advances in horizontal drilling technology have allowed drilling longer horizontal sections in the reservoir more efficiently and economically. While operators benefit from the well-known advantages of horizontal drains, such benefits cannot be maximized during the lifetime of the well without a viable well intervention means for well service and monitoring operations. Coiled tubing has been recognized as an effective technique for such interventions but with limitation on the total length that can be accessed especially in extended reach wells. This paper summarizes the utilization of innovative coiled tubing Tractor technology to improve coiled tubing accessibility in long horizontal wells.
Enhanced Cementing Practices Address Unique Issues Found With Solid Expandable Tubular Applications
Authors: Heathman James , Arredondo Eduardo , Olufowoshe Akin 
Published: December 2007

Abstract
New and innovative technology has a way of significantly influencing peripheral products and processes. A case-in-point is the relationship between solid expandable tubulars and cementing practices. The early years of cementing expandable casing were filled with researchers working to develop novel chemistries and resourceful techniques for annular sealants that varied from modified conventional cements to highly-specialized non-Portland systems such as resins. Experience and time relegated many of these chemistries and systems to specific situations.
Instead of needing atypical techniques and unique products, the more effective and applicable approach with solid expandables consisted of modified placement practices, training, logistics, and refined engineering of conventional cementing methods. But, as solid expandable tubulars are installed in deeper and higher-angled wells, annular sealant methods and products will be required to function in more extreme conditions.
This paper will examine the evolution of cementing processes and products for solid expandable tubulars. Emphasis is placed on best practices and lessons learned, with the intent of giving the reader a practical field guide. Checklists for key slurry design issues and how they correlate with the job logistics of the expansion operation will be included. This paper will also discuss foreseeable application trends in expandable use and logical modifications and enhancements in cementing procedures, technology and chemistries.
Formation Evaluation While Drilling Of a Complex Khuff–C Carbonate Reservoir in Ghawar Field, Saudi Arabia
Authors: Al-Fawwaz Abdullah , Al-Musharfi Nedhal , Butt Parvez , Fareed Abdul 
Published: December 2007

Abstract
Within the Saudi Aramco organization, complex reservoir formation evaluation is regarded as a key discipline - fulfilling a critical role in maximizing production and facilitating accurate estimation of reserves. The timely acquisition of high quality and detailed petrophysical properties of the various reservoirs in Saudi Arabia is central to this role. Towards this end, Saudi Aramco Reservoir Description Division (RDD) introduced a new-generation multi-functional LWD (Logging-While-Drilling) technology into Saudi Arabia, has been directed to evaluation of on-shore complex carbonate reservoirs.
The traditional LWD measurements of propagation resistivity, gamma ray, density and neutron porosity along with advanced gamma ray capture spectroscopy measurements into a single compact collar. The electronic pulsed neutron source required for the spectroscopy measurements also provides a much improved neutron porosity measurement1.
This technology has been used in a number of Saudi Aramco horizontal wells in carbonate and clastic reservoirs. The data from these wells has been comprehensively evaluated. The results of the evaluation of the data acquired by the new tool and conclusions about the tool's introduction into Saudi Arabia are summarized in this paper.
Reservoir Modeling With Global Scaleup
Authors: Wu X. H. , Stone M. T , Parashkevov R. R. , Stern D. , Lyons S. L. 
Published: December 2007

Abstract
We present a new global scale-up technology for calculating effective permeability and/or transmissibility. Using this innovative technology, we apply global flow solutions to improve scale-up accuracy. Global scale-up was proposed in the 1980s, and its benefits are well-described in the literature. However, global scale-up has not been adopted by the industry due to significant technical challenges in its application to real reservoir models. These models are often characterized by complex features like faults, pinch-outs, and isolated geobodies. Here, we overview several novel technologies that we have developed to overcome these difficulties.
Numerical examples applying global scale-up to several reservoir models are presented. Comparisons with local scale-up methods currently used in the industry are made.
The examples demonstrate that our new global scale-up technology leads to significant improvements in scale-up accuracy. In particular, when applied to challenging models with complicated fine-scale connectivity, the global scale-up method preserves the fine-scale connectivity more accurately than local scale-up methods. Sometimes, dramatic differences are seen. Moreover, we note that global scale-up can be especially effective when used in conjunction with unstructured grids.
Accurate scale-up is a critical link between fine-scale geologic descriptions and coarse-scale reservoir simulation models used for development planning and reservoir management. Predictive reservoir models that are consistent with geologic and production data gathered at different scales are critical for these tasks. Global scale-up is a promising technique for building more accurate reservoir models.
Success Story of a Waterflood Project in a Geologically Complex, High Viscosity Oil Reservoir in a Major Brownfield in South Oman
Authors: Choudhuri Biswajit , Al-Rawahi Mahir 
Published: December 2007

Abstract
A major reservoir in a large brown field in South Oman has been on production for more than 25 years. The reservoir comprises glacial sandstones of Palaeozoic age and is highly heterogeneous with wide variation in reservoir characteristics at scales smaller than well spacing. These variations include impermeable diamictite and shale beds and multi-Darcy gravel or conglomerate beds. The reservoir geology is further complicated due to the presence of faults and fractures that often provide highly conductive vertical pathways to the aquifer. The reservoir crude has high viscosity (90 cp) and moderate to low API gravity (22 deg API oil).
The field has been developed using vertical and horizontal wells in different phases of development. Water-flooding is in operation in the reservoir for more than 6 years. Injectors comprise vertical injectors in five spot pattern, horizontal injectors and inclined aquifer injectors in the flanks. Different water injection philosophy for different areas of the field has been adopted considering factors like primary drive mechanism operative in the reservoir, presence or absence of vertical barriers to flow, pre-existing field development pattern and more importantly future development for maximizing recovery from the reservoir over the entire life cycle.
Despite the geological complexity of the field and adverse mobility ratio conditions under which water-flooding is being carried out, the reservoir has responded very favourably to water flooding. The production decline trend from the reservoir has been arrested and reservoir pressure has increased in most areas of the field after initiation of water injection.
The paper presents the success story of water-flooding in a geologically complex reservoir containing high viscosity oil. The paper clearly illustrates that the success of a water-flood in a complex reservoir rests on implementation of a tailor-made development plan with flexibility to make changes to the same based on data from reservoir surveillance. The importance of well and reservoir management to maximize the value of waterflood is clearly brought out.
An Integrated 3D Volume Interpretation Approach is Successfully Used to Characterize Barriers to Flow within a Carbonate Reservoir
Authors: Al Khowaildi Shakir , Soroka William L. , Al Mehairi Yousuf 
Published: December 2007

Abstract
A method to quantify reservoir heterogeneities that should be included in a reservoir model to more accurately characterize a subsurface reservoir was successfully developed. Using a 3D volume interpretation approach it was possible to build a model of dense low porosity bodies within a reservoir layer that act as barriers to fluid flow. Pressure data confirmed cases where water injection wells were having negligible effect on up-dip production wells. The barriers to fluid flow were identified as a system of tidal channels and tidal pools, which were filled with dense, low porosity material, located within the porous reservoir layer.
A number of detailed studies were conducted to further identify and explain the occurrences of these dense bodies. The results of four independent studies were successful at characterizing the tidal channel-pool complex. The methods included seismic interpretation; well log analysis, seismic attribute analysis, deterministic and stochastic inversion and acoustic impedance to porosity volumes. When the fine details of the different studies were compared it was recognized that the different approaches used to identify the dense bodies showed subtle differences in size, location and geometries of the dense bodies.
A 3D volume interpretation approach was successfully used to integrate the different results and produce a most likely dense body model. The 3D volume interpretation included 3D visualization, co-rendering of multi attribute volumes, seed detection and use of available well control. Several wells had been drilled through the dense tidal channels and ponds and where used as calibration points to validate the analysis.
The final 3D geo-body model was provided to the reservoir modelers for incorporation into the geologic model. The addition of these subtle geologic features in the reservoir model is important for improved well planning, simulation and oil recovery.
Permeability and Microscopic Displacement Efficiency of M_1 Bimodal Pore Systems in Arab D Limestone
Authors: Clerke Edward A. 
Published: December 2007

Abstract
Extensive and detailed studies of the pore systems of the Ghawar Arab D limestone have been captured in very large mercury injection capillary pressure data sets1–3 in which all data have been analyzed using Thomeer functions4–6. These data give new insight into the pore geometry dependence of the reservoir dynamical properties: permeability and imbibition oil relative permeability7 and yield ultimate recovery rock types with algorithms for rock type based reservoir simulation studies of ultimate recovery. New carbonate petrophysical concepts are established.
The dominant subgroup of the examined carbonate limestone pore systems comprise the major Arab D reservoir section are denoted as an M_1 bimodal pore system3. The M_1 bimodal pore system consists of a macropore system (M), with a well defined and wide distribution of pore throat diameters and geometries, in conjunction with Type 1 microporosity with equally well defined and narrow distribution of pore throat diameters and geometries. This bimodal M_1 pore system results in a mixed wet reservoir condition in the bulk of the reservoir.
The role played by the macro and micro pores of the M_1 pore system has been related to the reservoir dynamical properties: permeability and relative permeability7. This work demonstrates fundamentally new pore geometry based formulations for calculating permeability and imbibition oil relative permeability and therefore delineates the pore geometry based variation in microscopic displacement efficiency for variations within these systems. For these reservoir rocks, the appropriate pore geometrical parameters to perform ultimate recovery rock typing have been identified.
This paper presents data and formulations for improved pore system based models of permeability and imbibition oil relative permeability in the M_1 bimodal pore system that reproduce measured laboratory data over a range of oil relative permeability from 1 to 0.0001 for seven waterflood composites. The relative permeability formulation uses two attributes of the pore system: permeability (already shown to be a function of pore geometrical parameters) and the volume of Type 1 microporosity alone. Both of these can be extracted from appropriate processing of appropriate well log data. These results show that shifts of the oil relative permeability curve to increasing water saturation (the right) commonly ascribed to wettability changes, result in this case from increasing the amount of Type 1 microporosity in the M_1 bimodal system which add an "ineffective" water saturation to the relative permeability water saturation axis.