bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Environmentally Friendly Clay Stabilizer
Authors: El-Monier I. A. , Nasr El-Din H. A.
Published: July 2010

Clay stabilizers are means to prevent fines migration and clay swelling, which are caused by the contact of formation with low salinity or high pH brines. Previous clay stabilizers including: Al and Zr compounds and cationic polymers have several drawbacks. Al and Zr compounds can be removed by acids. Cationic polymers can cause formation damage in some cases, and their environmental impact is questionable. There is a need to develop new clay stabilizers that can work following acid treatment and are environmentally acceptable.

Laboratory studies were conducted on newly developed Al compound. Zeta potential and particle size measurements were used to determine surface charge of four types of clays: kaolinite, illite, montmorillonite, and chlorite; and to optimize clay stabilizer concentration. Coreflood experiments were conducted on Berea sandstone cores (1.5 in. diameter and 6.0 in. length) to assess the effectiveness of the new compound and determine the impact of acids on its performance. Atomic absorption was used to measure the concentrations of Al, Mg, Ca, and Fe in the core flood effluent.

The new clay stabilizer was very effective in mitigating fines migration. Zeta potential indicated that the isoelectric point at which complete shields of surface charge of clay particles was achieved at a stabilizer concentration of 0.2 wt%. Coreflood tests showed that this new chemical was effective, and unlike previous Al compounds, it did not dissolve in acids. In addition it is environmentally friendly compound, and also worked very well at 200°F. The behavior of the new stabilizer was much better when it was prepared in DI water than in brine.
Effectively Enhancing the Near-Wellbore Stimulation Treatment Using Fluidic Oscillation Technique
Authors: Kritsanaphak Kritsana , Tirichine Salah
Published: July 2010

Near-wellbore damage can cause severe reduction in effective permeability and production. A typical solution for near-wellbore damage removal involves wellbore cleanout and squeezing the treatment fluids into the formation through perforation with a conventional jetting-nozzle run on coiled tubing. However, there are numerous old wells in North Africa oil fields that have been completed with a slotted or preperforated liner and require an effective near-wellbore stimulation to remove the damage and restore the near-wellbore permeability and production.

A fluid-oscillation technique created by a fluidic-oscillator (FO) tool was applied successfully in conjunction with stimulation treatments, such as matrix acidizing, salt, and asphaltene treatment. The results from using this tool instead of the conventional jetting tool were significant. The post-stimulation production improved over previous stimulation gains when performed on the same wells. Recently, the fluid-oscillation technique was also applied effectively for near-wellbore stimulation treatments in horizontal wells without requiring matrix squeezing. Results from using this technique have been promising and have simplified the near-wellbore damage treatments. Several wells in this field were treated using this near-wellbore stimulation treatment, resulting in significant production gains. Using the matrix and near-wellbore stimulation in conjunction with the FO tool has become the preferred method to enhance the effectiveness of treatments.

The FO tool creates pressure waves within the wellbore and formation fluids that break up near-wellbore damage to restore and enhance the permeability of the near-wellbore area. As the damage is removed and the original permeability is restored, the pressure waves can penetrate deeper into the formation matrix for more complete damage removal. The direct comparative results from using conventional jetting nozzles and FO tools for several wells in a North Africa oil field are quite evident and are presented in this paper. This technique should help other operators enhance the effectiveness of near-wellbore treatments to achieve similar benefits.
An Analysis of CO2 Storage Prospects in Deep Saline Reservoirs
Authors: Huo Da , Jalali Younes
Published: July 2010

We analyze the prospects of CO2 storage in deep saline reservoirs. Our analysis indicates that the outlook for this method of CO2 storage is favorable. Although this is a subjective assessment, we attempt to clarify the factual trends underpinning this perspective. This includes the robust trend in growth of natural gas demand, severity of the sour gas problem, precedence in governmental action in the form of fiscal deterrents to CO2 emissions and stimulants for geological storage, and the large footprint of deep saline reservoirs.

It is therefore not surprising that the few industrial-scale projects implemented for direct storage of CO2 in geological formations all adhere to the same blueprint – sour gas fields in relative proximity of deep saline or bottom-water reservoirs, developed in countries where government is adopting a proactive approach to curbing CO2 emissions, by levying tax and by assuming the long-term liability of these projects.
Modeling of Crude Oil Asphaltenes Deposition: In-depth Colloidal Prospective
Authors: Al-Huraibi Nasser , Belhaj Hadi
Published: July 2010

Asphaltene deposition may occur during primary or gas miscible injection recoveries, taking place almost at any stage of production from the reservoir all the way to surface facilities. Change of reservoir oil chemical composition, temperature and/or pressure during depletion leads to a state of disequilibrium that induces asphaltene precipitation causing major production problems. Asphaltenes are the polyaromatic and polar components of crude oil that are insoluble in lower molecular fractions of oil but soluble in toluene and benzene. Numerous experiments and investigations have been performed on crude oils in an attempt to understand asphaltene precipitation phenomenon that profoundly affects the economics of oil production in many reservoirs around the world. However, the problem with these experiments lies in the fact that they predominantly apply identical approaches to investigate asphaltene short-term removal and not digging enough into preventive measures.

This study presents a novel approach to tackle the asphaltene deposition problem by virtue of applying a DC current on an oil sample to move the asphaltene colloids to one of the electrodes. Asphaltene colloid particles in this experiment proved to possess negative charges. Evidently, the asphaltene particles moved and deposited on the anode resulting in all the asphaltene being extracted from the oil. The use of an electric current in this experiment shows that this approach can be implemented in the reservoir by drawing all the negatively charged particles to a dumpster well as discussed below. Results from the experimental work and analyses are very encouraging for more investigation that might lead to something that sought for the longest time.
Novel Fluid Formulations to Remove Mud Filter-Cake without Affecting Rock Mineralogy
Authors: Fakhreldin Y..
Published: July 2010

Removing filter-cake is essential for reducing the formation damage caused by drilling activities in various production and injection wells. These filter-cakes typically contain bio-polymers such as xanthan gum, poly-anionic cellulose, starch, along with bridging agents such as sized calcium carbonate particles. A novel chemical series was applied in laboratory tests; it perfectly degrades the filter cakes. Different performance tests showed that the filter cake was entirely removed after being treated with the novel chemical series. A direct reaction between the drilling mud and the novel compounds resulted in a complete loss of mud viscosity. Encouraged by the above data; core flood analysis were performed to test the effectiveness of the novel compounds on sandstone cores. The scenarios, which might occur in field applications, were simulated in the laboratory under controlled conditions and the responses of the core samples under these conditions were measured. Return permeability were approximately 100% after treatment with the new compounds. There was no swelling of the interstitial clay component of the formation plugs over a remarkable duration of time and wide range of temperatures.
Hydraulic Fracturing in Iran-Lessons From Four Case Histories
Authors: Heydarabadi F. Roshanai , Moghadasi J.. , Safian Gh. A.
Published: July 2010

From decades ago till now, most oil wells in Iran produce using their natural flow potential and they don’t need to be fractured. This is why few cases of hydraulic fracturing are recorded in the history of Iranian oil industry. This paper reviews the three cases of acid fracturing previously conducted in an Iranian oil field based on the available data. In addition, a mere propped fracturing was also designed to be carried out but due to some problems the whole operation was cancelled. As time goes by, the reservoir pressure depletes and the need for hydraulic fracturing as stimulation practice arises. Studying the previous fracturing jobs is beneficial when designing a new treatment, thus lessons can be learnt from them.

The status of the candidate selection of these wells is discussed firstly in this paper. It is important to choose appropriate wells for such an expensive stimulation practice as hydraulic fracturing. Through modeling the wells the effects of fracturing on the production performance, i.e. production rate, of these wells are considered. A successful hydraulic fracturing should improve the productivity of the well. The available build-up tests are also investigated to diagnose any induced fracture in the formation. Fracturing the formation changes the flow regime around the wellbore and this change can be distinguished through analyzing pressure transient testing data.
Hybrid AI and Conventional Empirical Model for Improved Prediction of Log-Derived Permeability of Heterogeneous Carbonate Reservoir
Authors: Weldu Tadesse , Ghedan Shawket , Al-Farisi Omar
Published: July 2010

Proper permeability distribution in reservoir models is very vital for reliable full field development and optimization in terms of well placement and completion strategy, managing wells’ and field’s production and injection rates in addition to estimating the recovery factor. Despite its importance, however, it is still one of the most difficult petrophysical properties to model or predict accurately.

Reliable permeability data are those derived from core measurements conditioned to well-test permeability. In most cases, however due to cost and other issues, no more than 10% of the reservoir wells are cored. To fill the gap, many approaches have been undertaken to predict permeability in the non-cored wells from log data.

Besides conventional empirical techniques, recent studies show that Artificial Intelligence (AI) technologies can predict permeability from conventional well logs with better accuracy. This study employs hybrid of both approaches to improve the prediction of permeability of a very heterogeneous carbonate reservoir.

This study was conducted in three main phases. In the initial phase, reservoir layers were grouped considering data availability and layers’ lithology, and petrophysical data. Then each group was divided into at least three clusters depending on porosity and core permeability cross-plots. In the second phase, Adaptive Neuro Fuzzy Inference System (ANFIS) has been designed to predict the index of the rock clusters based on wells’ GR, Rxo, and Porosity logs. The final phase encompassed the utilization of conventional curve fitting techniques to predict the permeability. This prediction was further improved by introducing corrections depending on the core versus predicted permeability cross-plots. Considering the heterogeneous carbonate reservoir under study, this hybrid approach proved to be superior over applying either the conventional approach or the Artificial intelligence method. Plots of depth versus core and predicted permeability shows very good match for all wells considered in this study.
Expanding the Role of Resistivity Image Logs Using Improved Acquisition and Interpretation Techniques
Authors: Kuchinski Robert , Kalathingal Paul
Published: July 2010

The use of the resistivity image data is becoming a more common tool in the search and development of hydrocarbon accumulations. Regardless of the resource type, play type or environment of deposition, image data is becoming more important in order to assess the potential of these reservoirs.

This paper will discuss the advances in technology on the hardware side that allow for the acquisition of higher quality image data in routine and extreme borehole environments. The use of improved processing techniques will also be discussed which allows for improved reservoir characterization in a wide range of reservoirs compared to only using the conventional open hole log suite. The high resolution quality of image data compared to the basic open hole data, for example will allow for fracture visualization down to 2mm. Other petrophysical analysis using basic open hole data will average out the fine details of the fracture and its effects on porosity and permeability. Image based petrophysics known as "Image petrophysics" allows for the conversion of high resolution image data to high resolution petrophysical properties which provides greater understanding of the impact of the fractures on reservoir characterization. The use of image data calibrated with either core data or basic open hole data allows for the derivation of high resolution porosity distribution. Permeability derivation can also be achieved using image data calibrated with core data. This process can also be extrapolated to wells that are un-cored.

This paper will also discuss the challenges of acquiring image data from challenging borehole environments by employing memory based image tools that can be conveyed using a broad range of conveyance techniques.
A Decision Support System for Cost-effective Assessment of Sand Production Risk and Selection of Completion Type
Authors: Rahman Khalil , Khaksar Abbas , Kayes Toby
Published: July 2010

Mitigation of sand production is increasingly becoming an important part of field development as the petroleum industry is expanding its production operations in more challenging unconsolidated rocks and depleted reservoirs with more complex well completion architecture. Reliable sand production assessment methods are essentially based on geomechanical approaches that integrate in-situ stresses, reservoir pressure and its depletion trend, rock strength, well trajectory, completion type and planned drawdown. Use of grossly empirical, often unreliable, methods to infer sand production risk could result in either unnecessary an upfront sand control cost or sand management cost during production due to unpredicted sanding.

This paper demonstrates by application to a field case in South East Asia how to develop and use a decision support system for credible sand production assessment and completion selection. Once a geomechanical model is built and sand production assessments have been carried out for a few wells by a robust sand production prediction model, the knowledge and information can be converted into a decision support system for new wells in the field. Provided the field Earth stresses and the reservoir pressure are applicable, the system then needs only a log-derived rock strength profile for sanding evaluation and decision making for new well trajectory and completion configuration. Using the existing geomechanical model, calibrated log-derived rock strength profiling and field supported sanding prediction, a simple flow chart is developed to assist well engineers to decide the completion type by taking into account the risks of sand production and hole collapse during production. The availability of such a decision support system assists the well and production engineers to follow a quick, cost-effective, simplified but sound approach for sand production assessment and completion selection as opposed to being grossly empirical, or too rigorous.
Unlocking the Low Frequencies for Improved Relative Impedance Inversion
Authors: Martin Iain , Helmore Steve
Published: July 2010

Seismic inversion techniques aim to estimate impedance and hence the Earth’s rock properties. Due to the band-limited nature of seismic data, estimates of absolute impedance require a low frequency scalar model estimated from horizon interpretation, well data and stacking velocities. Whatever deterministic inversion algorithm is employed, model assumptions and artefacts are embedded in an absolute impedance result.

Relative impedance inversion workflows avoid the pitfalls of a low frequency model by employing the seismic data alone, and are a fast and cost effective alternative when absolute impedance is not required. A typical workflow can be summarised by: Zero phasing of the seismic data by well ties or statistical methods; Relative impedance (‘Coloured’) inversion by spectral shaping and 90 degree phase rotation; Horizon based amplitude extraction and calibration.

The spectral shaping process applies a filter to the seismic reflectivity data to match it to the local well impedance spectrum. By wedge modelling we show that the range of bed thicknesses consistently imaged by the relative impedance is affected by the impedance wavelet characteristics, particularly the characteristic decay (α) of the spectrum with frequency, the low frequency cut-off, and the high frequency cut-off.

The decay (α) is determined by the local fractal layering of the earth and hence the log impedance spectrum. The degree to which the high and low frequency events can be imaged by seismic is limited by noise, and we can extract maximum value from the relative impedance result when the inherent impedance wavelet has high bandwidth.

Impedance data is particularly rich in low frequencies as a natural consequence of the Earth’s layering, and it is this low frequency bandwidth that new post-processing techniques aim to improve. Simple relative impedance inversions suffer from the amplification of low frequency noise if the shaping operators are pushed to their limits, creating a characteristic ‘curtain’ effect. We show how two recent processing techniques have solved this problem, extending the low frequency bandwidth often to as low as the acquisition low frequency cut-off.

The first innovation is to design and apply the inversion operator before migration, which reduces the problem to a 1D convolution and reduces low frequency noise. We demonstrate the improved performance of Coloured Inversion using this technique and the added value to a data set from West Africa.

The second innovation involves the application of structurally oriented filters to selected (low) frequency bands to improve signal to noise conditions prior to applying the inversion operator. We illustrate this technique with an example of relative impedance elastic inversion from the UK North Sea.

Using these pre-processing techniques on seismic data it is possible to produce products with high bandwidth and correctly estimate relative impedance over a large range of bed thicknesses, delivering valuable insights to the interpreter.
Evaluation of Triazine-Based H2S Scavengers for Stimulation Treatments
Authors: Al-Duailej Yaser K. , Al-Mutairi Saleh H. , Al-Humaidan Adel Y.
Published: July 2010

Acidizing fluids perform their functions through complicated processes, hence, require additional additives to achieve wanted goals and prevent harmful side effects. Examples of these additives are diverting agents, corrosion inhibitors, surfactants, de-emulsifiers, and iron control agents. These additives should be designed to perform in a compatible and synergetic way with other additives. In this paper, triazine-based hydrogen sulfide scavenger was investigated for its scavenging capacity in various fluid formulations and its compatibility with several additives.

To determine the scavenging capacity of the scavenger, an experimental method was developed. In this method, hydrogen sulfide (H2S) was generated by reacting hydrochloric acid (HCl) with iron sulfide (FeS), passed through a solution containing a triazine-based scavenger, and trapped in cadmium sulfate (CdSO3) solution. Then, the scavenging capacity was measured using gravimetric method. Furthermore, several testing parameters were investigated including amount of generated H2S, flow rate, concentration of scavenger, and type of solvent. All experiments were carried out in and aquatic neutral and acidic solutions at an anaerobic atmosphere and ambient conditions.

The second part of investigation was the compatibility of hydrogen sulfide scavenger with common acidizing additives. The objective was to determine the damaging or hindering effect caused by these additives. Tested additives were mutual solvents and quaternary ammonium corrosion inhibitors.

Water was found to be a suitable solvent for the tested scavenger. In contrast, the scavenging capacity declined dramatically when HCl was used. Therefore, optimum scavenging capacity, using water as solvent, was determined based on extensive testing that included parameters such as concentration of scavenger, amount of H2S, and contact time. Also, the tested additives were found to reduce the scavenging capacity.
A Novel Fracture Characterization Approach: Mini-DST Using a Wireline Formation Tester
Authors: Widjaja Danang R. , Alhuthali Ahmed , Guerrero Rodolfo Phillips , Lyngra Stig , Rourke Marvin
Published: July 2010

A good understanding of the fracture characteristics is essential for a successful development of a tight, heavily fractured reservoir. The fractures play a major role for both reservoir fluid flow and well productivity. An efficient fracture characterization is required to understand the recovery mechanism, which is critical for field development and optimal production strategy decisions. It is imperative that state-of-the-art dual-porosity/dual-permeability models are populated with accurate fracture descriptions to provide reliable forecasts.

This paper describes a novel approach to characterize fracture properties by using image logs, formation tester with straddle packers, and pressure transient analysis (PTA). The image logs are used to identify fracture systems along the wellbore. The formation tester with a straddle packer is used to isolate each system shown on the image logs for separate pressure drawdown and buildup testing. The fluid type filling the fractures can be identified during drawdown. The acquired pressure responses are interpreted by PTA to calculate the fracture properties and to determine the fracture role in the recovery efficiency.

Several essential results have been obtained. Range of matrix anisotropy, kv/kh, has been concluded. Role of small scale fractures on recovery mechanism has also been better understood.
Improving Seismic Whitening and Seismic Inversion Workflows Using Frequency Split Structurally Oriented Filters
Authors: Helmore Steven , Martin Iain
Published: July 2010

This paper describes a seismic processing method that uses dip-steered filtering to improve the performance of subsequent seismic whitening and relative impedance inversion. Given favourable acquisition and processing parameters, the availability of high frequency signals is ultimately limited by poor Signal/Noise ratio (S/N) at high frequencies. Managing this noise is key to accessing the high frequency information.

We show that although spatial filters applied to broadband seismic data mainly affect the central pass-band, a frequency splitting approach can specifically benefit targeted high frequency ranges in the spectrum. The dip steered filters trade spatial resolution for increased S/N, but only in targeted frequency bands that are boosted during the subsequent whitening process.

The S/N of the low frequencies can be improved using a similar process prior to acoustic impedance inversion. In a relative impedance inversion workflow, de-noising the low frequencies allows accurate inversion of thicker beds. Applying the technique prior to full-bandwidth inversion allows the use of lower seismic frequencies, and reduces reliance on a pre-existing background model.

We can apply frequency split dip-steered filtering to pre-stack common offset volumes or partial stacks in a similar fashion. This delivers frequency balanced partial stacks with lower noise and increased resolution, ultimately leading to a reduction of offset dependent tuning and higher resolution elastic inversion products.

Logs are not required for the process but independent well ties demonstrate the validity of the technique and are used to QC the products. The value of increased resolution in the seismic data volumes is illustrated with several case histories from different surveys and reservoirs.
Leveraging Slim Hole Logging Tools in the Economic Development of the Ghawar Fields
Authors: Ariwodo I. , Al-Belowi A. R. , BinNasser R. H. , Kuchinski R. S. , Zainaddin I.
Published: July 2010

Traditionally, brown field developments have often required the plug back and sidetrack of existing drain holes, to target any nearby opportunities. With advances in drilling technology, there is a general preference to drill small diameter wells due to the comparative cost advantage.

In the recent times, this preference has led some wireline service companies to start to offer open hole formation evaluation services with slim tools having a diameter in the 2" to 2½" range. At present, most of the traditional petrophysical measurements can be acquired utilizing slim tools. In addition, several "specialized" measurements, such as cross dipole sonic, formation pressure testing, and resistivity imaging can also be acquired. The use of battery and memory technologies has allowed these tools to be deployed using a broader range of conveyance techniques allowing for reduced risk in the entry of slim wells.

The provision of slim hole logging services has created an opportunity in the industry to leverage these tools for the economic development of brown fields. Therefore, short horizontal sidetracks and well re-entry’s to test deeper horizons can be drilled and logged successfully. Saudi Aramco has been able to leverage these tools in its continued development of the giant Ghawar field. Some of the development projects are listed below: Some horizontal sidetracks with 3⅞" hole sizes have been drilled under higher doglegs than was previously possible, and logged successfully.It is now possible to run well completions in newly drilled wells that have a well control problem. A provision is made to subsequently log these wells with slim wireline logging tools.It is now possible to run a complete suite of wireline logs across some old wells that were previously completed without a full formation evaluation logging suite.Slim hole formation resistivity imaging services are now being provided, to aid in the identification of borehole breakout and fracture features that might affect the well’s productivity.Slim hole formation pressure testing has been acquired in slim wells to generate a pressure gradient, determine oil mobility, and define oil-water contacts.

Several case studies will be used in this paper to demonstrate how Saudi Aramco has leveraged these slim wireline tools to realize some development opportunities. Also, examples will be used to show that these slim tools do not compromise the quality of log data acquisition.
A Novel Command Activated Sandface Valve To Improve Wellbore Productivity
Authors: Adam Malcolm , Coull David
Published: July 2010

A novel command activated sandface valve was developed that has significantly improved productivity by enabling improved wellbore clean up, particularly in high angle and open hole completions. The sandface valve technology has now seen 35 valves installed with a functional 100% success rate. Further wells are planned for a North Sea field utilizing this technology. The command activated sandface valve development was taken from concept to installation in 5 months including operator engineering reviews.

Inefficient wellbore clean up of highly deviated completions is common in production wells. Current solutions include Smart well technology or time consuming clean up procedures that are both expensive and difficult to implement. Poor clean up can lead to loss in well productivity, restricted access to reserves and in some cases a requirement to sidetrack the well.

An operator in the UK had observed no flow from the toe of the well while experiencing high drawdown at the heel section due to the dominance of high productive intervals.

The command activated sand face valve was developed from an operator’s requirement for more time control when selectively cleaning up/flowing the reservoir sections. The key objectives of the valve were to allow sequential clean up of the reservoir section from the toe to the heel without intervention or incremental rig time. The valve would be activated by a pressure recognition signal and also had to deliver the functionality of a sliding side door for future water shut-off capability along the well bore. The paper will present an overview of the technical challenges, detail development of the tool and processes used for assurance, and include results of the field trials.

The valve design combines a field proven timer activation mechanism, a transducer and conventional sliding sleeve technology. The tool was developed without external resource and cost often required for product development. Development of the valve was closely monitored by the operator which included a technical assurance review and failure mode and effects analysis process. The result is a successfully field proven completion tool that is the basis for a new completion technique that has application in high angle wells in all oilfield applications.
Value of 3D Geomechanical Modeling in Field Development - A New Approach Using Geostatistics
Authors: Holland M. , Brudy M. , van Der Zee W. , Perumalla S. , Finkbeiner T.
Published: July 2010

In recent years, the petroleum industry achieved marked advances in the development of full 3D and 4D geomechanical models. If robust, these 3D/4D models provide the benefit for more accurate well and field development planning in structurally complex settings such as areas with significant topography or/and faulting, when substantial depletion is likely to cause changes in the in situ stress field accompanied by reservoir compaction and even surface subsidence, or due to the presence of salt diapirs or other frictionless bodies/layers with different material characteristics. In most cases, these 3D/4D geomechanical models also require advanced finite element modeling coupled with reservoir simulation. In these instances, in particular understanding the in situ stresses, pore pressure, and material properties and their variability (lateral, in depth as well as with time) is of critical importance to better evaluate and mitigate risk during the drilling, completion, and production phase of a field development.

However, not all fields require the finite-element approach. In this paper, we demonstrate how a 3D geomechanical model can be build in a structurally relatively straightforward setting based primarily on an existing structural model and augmented with well data under application of appropriate geostatistics techniques to map and interpolate rock properties (such as density, rock strength, internal friction, etc) along the structural grid directly linked to the field's stratigraphy. This type of 3D geomechanical model has a clear advantage over a 1D depth-stretched model by honoring structural and stratigraphic constraints. This is particular important when an operator plans to drill a high number of directional or even horizontal wells and needs to capture varying stresses, pore pressures, and rock properties on the field scale to optimize well integrity. At the same time, this geomechanical model also provides benefits over 3D numerical modes in terms of timing to build the model, cost, flexibility to update the model (with data from additional offset wells) and accessibility across disciplines in the asset team. For example, it is straightforward to export data along planned trajectories for conventional wellbore stability analyses.
Effect of Temperature and Pressure on Interfacial Tension and Contact Angle of Khuff Gas Reservoir, Saudi Arabia
Authors: Okasha Taha M. , Al-Shiwaish Abdul-Jalil A.
Published: July 2010

Knowledge of reservoir fluid properties is essential during the development phase, and to implement an optimal reservoir management strategy for properly exploitation of tire reservoirs. Interfacial tensions (IFTs) of reservoir fluids, as well as the contact angle are important parameters for many reservoir engineering studies. Examples are imbibition studies and calculation of fluid saturation in the gas-oil transition zone.

Both IFT and the contact angle of the fluids/rock system affect the distribution of fluids within reservoir rock material. The fluids distribution strongly affects the flow behavior and hydrocarbon recovery. Most of the available data, contact angle and IFT for crude gas/brine systems are for room temperature and atmospheric pressure. Since actual values of reservoir temperature and pressure are frequently encountered in oil field simulation models, a need to study IFT and the contact angle at reservoir conditions was recognized. This paper is an investigation of the influence of temperature and pressure on IFT and the contact angle of Khuff gas and condensate fluids.

Experimental results of IFT for Khuff-C gas/brine system and condensate A, B and C/brine system over a range of temperatures and pressures are reported. Also, results of the contact angle for various samples of condensate/brine/rock material systems are documented. The IFT between Khuff-C gas and brine decreased with increasing temperature at the maximum system pressure of 3,000 psi. Condensate composition effects on IFT were seen for various condensate samples (Khuff-A, B and C ). The contact angle values for Khuff-C gas/brine/rock material system decreased with both temperature and pressure.
Determination of Reservoir Rock Wettability by Thin Layer Wicking Approach
Authors: Yildiz Hasan O. , Oztorun F. Bahar , Sirkeci Ayhan A.
Published: July 2010

The present study was an attempt to investigate the possibility of contact angle determination of two immiscible fluids in contact with the solid surface of a porous material with heterogeneous mineralogical composition. Since the contact angles are measured on a single mineral’s crystal, the question of how representative the results of wettability of the rock containing many different constituents arise. Due to the roughness, heterogeneity, and absorption ability of porous surfaces of reservoir core, the direct measurement of contact angle is not applicable. When contact angles cannot be directly measured, the measurement of capillary rise in a bed of particles can be used to quantify wetting characteristics of the solid. The main objective of this study was to investigate the determination of rock wettability by Thin Layer Wicking approach. The application of the Washburn equation for dynamic measurement of contact angle and the method of Thin Layer Wicking were described. Experiments were conducted on the powdered samples of different sandstone and limestone rock samples and also their representative pure minerals such as quartz and calcite, respectively. As a wicking test liquid, distilled water, 2% NaCl brine, kerosene, and mineral oil were used, and their contact angles with respect to the sample’s solid surface were calculated. Powdered sample of quartz mineral was proved to be more water-wet than powdered sample of calcite mineral. Furthermore; the contact angle values of carbonates are closer to that of calcite while the contact angle values of Berea and Bentheim sandstone are closer to that of quartz. This study is the first Thin Layer Wicking study in Petroleum and Natural Gas Engineering Field, and it can be a leading survey to attempt new investigations in this subject.
Effect of Borehole Inclination, Annular Clearance, on the Hole Cleaning Efficiency for Water Based Drilling Muds
Authors: Noui-Mehidi Mohamed N. , Amanullah Mohamed
Published: July 2010

In the case of deviated, horizontal, extended reach and multi-lateral wells, the existence of a particle bed and also the formation of a partially or completely buried cuttings bed can be problematic for borehole cleaning. As a solution increasing the drilling fluid velocity can help in eroding the deposited bed substantially above a critical velocity, which depends on several flow parameters. For instance pipe rotational speed can enhance particle transportation at flow velocities lower than the critical annular fluid velocities as reported in the literature. The consequences of pipe rotation on the fluid transport ability are also subject to the inclination of the drilled section. The present paper discusses the results of numerical simulations of water based drilling fluid flows regarding the inclination effect, the fluid viscosity, the clearance between the pipe and the borehole and the resulting pressure losses.
Azimuthal AVO in Coal Beds, Western Canadian Basin: A Promising Method for Characterizing Fractures in Unconventional Gas Reservoirs
Authors: Al-Duhailan Mohammed A. , Lawton Don C.
Published: July 2010

Seismic analysis was conducted to predict the orientation of the dominant fracture (cleat) system in a Cretaceous coal bed gas reservoir within the unconventional Coal Bed Methane (CBM) play in central Alberta, Canada. The extension of the method of analyzing the variation of seismic amplitude as a function of offset (AVO) to include analysis of amplitude variation as a function of azimuth (azimuthal AVO) was utilized. This technique was applied to characterize seismic azimuthal anisotropy, which indirectly predicts fracture system orientations.

The study focuses on identifying the azimuthal variation of the AVO response of the coal bed. By calculating three azimuthal AVO gradients from 2D multi-azimuth walkaway vertical seismic profiles (VSPs), the study revealed the existence of azimuthal anisotropy. A mathematical solution using these calculated AVO gradients defines the direction of the maximum change in amplitude with offset. This direction is always perpendicular to the orientation of the dominant fracture system.

The reliability of the approach used in this study demonstrates a promising method for characterizing fractures in unconventional gas reservoirs.
Production Optimization of Multi-Lateral Wells Using Passive Inflow Control Devices
Authors: Hembling Drew , Berberian Garo , Al-Mumen Adib , Simonian Sam , Salerno Giovanni
Published: July 2010

Passive ICDs (Inflow Control Devices) are being used to enhance performance of horizontal wells in unfavorable enviromnents such as non-uniform permeability and/or pressure variations along horizontal sections. This is the first ever attempt, to the best of our knowledge, at using ICDs to manage inflow from two laterals connected to a motherbore. Furthermore, this well is a 3 7/8" openhole multi-lateral with a 2 7/8" ICD completion.

This paper presents how passive ICD completion technology is used to optimize well productivity in a multi-lateral well. This carbonate well was sidetracked to increase reservoir contact and create tire required multi-lateral. Subsequently, the ICDs were run, and to confirm the inflow profile along the length of the of the ICD completion, a PLT survey was conducted. The actual rate and inflow profile compared favorably with the predictions as per design of the ICD completion. This paper will show the well design, the actual PLT vs modeled results, and discuses future utilizations for this technology.

The key factor in the success of this project was the use of the 2-7/8" ultra-slim ICD completion, which was optimized based on numerous wellbore hydraulic simulations, to determine the appropriate number of ICD units and compartments to balance the required off-take from each lateral, and from individual compartments in the motherbore section.
Optimized Field Development of an Offshore Carbonate Reservoir in Saudi Arabia
Authors: Dismuke Carl T. , Jokhio Sarfraz A. , Mubarak Hassan K. , Shuaibi Anas A.
Published: July 2010

A relatively large carbonate reservoir located offshore Saudi Arabia was developed over the last several years to augment production capacity. The objective was to raise the Field-A oil production capacity by an additional 25% to help offset downtime occurring on existing production platforms due to workover and facilities upgrading operations. In this paper, the development project scope, implementation, simulation, use of technology and drilling activities that resulted in a successful implementation of the development plan for the Field-A Reservoir-4, as well as the initial results, will be discussed.

The development was placed on a fast implementation schedule and was carried out during a high oil demand period (2006-2009) that placed large constraints on delivery of new equipment and platforms. The production increment was successfully brought onstream within a 3-year timeframe. The development plan included the installation of three platforms for both oil production wells and power water injectors as well as several sidetracks to add sustainable production capacity. Key wells were equipped with permanent downhole monitoring systems to monitor reservoir pressure performance in real time and the newly drilled producers were completed with electric submersible pump (ESP) lift systems. In addition, the first application in Saudi Aramco of a distributed temperature sensor (DTS) system was deployed in an injector to obtain real time flow profiles along the wellbore section.

The overall development project utilized a number of existing assets to minimize the development cost and trial testing of the innovative applications, such as using existing wells for on-platform water injection that consists of a water supply and an injection well combination while both located on the same platform, and an inverted ESP assisted water injection.

Reservoir simulation studies were used to optimize the wellbore placement and indicated the oil production plateau could be sustained for an extended period.
Using Inter-Volume Similarity Measures as a QC Tool for Seismic Data Processing
Authors: Dossary Saleh A. , Al Garni Khalid , Cunningham George , Al Saad Riyadh
Published: July 2010

Five seismic attributes are proposed to efficiently compare seismic volumes. Two attributes are derived directly from the input datasets, three are derived from a cross correlation of the datasets. All attributes are calculated in a time-sliding window.

The proposed method can be used to verify that consistent phase, e.g. between marine and land datasets, has been used or how attributes such as phase, amplitude or time have changed during a processing workflow. We show the effectiveness of our method by applying it on synthetic and a real datasets.
A Case Application of Geostatistical Inversion of 3D Seismic and Well Data for Enhanced 3D Reservoir Property Modelling
Authors: Udofia Abasiubong , Olotu Sam , Onyekonwu Mike O.
Published: July 2010

A major challenge in reservoir property modelling is integrating the resolution obtained in well logs and the lateral reach of seismic data to obtain a representative model. The seismic data and well logs are recorded as independent pieces of data, each giving subsurface information with different attributes. Recently, solutions to this challenge have emerged in a number of ways. In this case study, implementation was based on a Stochastic Simulation procedure that populated the inter well space with reservoir properties directly linked to 3D seismic and well data. Basic construction principles were geostatistical, though different from conventional geostatistical practices in the sense that in addition to honouring the available well log data, the simulation was conditioned to fully honour the existing seismic data between the wells.

Converting petrophysical properties into acoustic properties that are related to seismic attributes required detailed univariate and multivariate analysis of reservoir properties and acoustic impedance relationships and geostatistical analysis of rock properties at the well log scale.

This approach provided the petrophysical properties in the inter well volume from the absolute acoustic impedance volume. The acoustic impedance volume was derived from geostatistical inversion of the 3D seismic volume and using the vertically detailed impedance realisations as secondary data, and the well porosity as hard data a sequential Gaussian cosimulation was carried out for generation of the porosity models. 3D permeability model was also built from the mean porosity cube utilizing a regression equation

The case study demonstrates the robustness of this approach. A lateral prediction of petrophysical properties was carried out for the reservoir sands in two Niger Delta fields and the resulting acoustic impedance cube and property cube were used to constrain the reservoir static model. These fields have highly stratified clastic reservoirs. The fields structural style consists of complexly faulted collapse crest roll over anticline.

3D porosity and permeability model were built, the seismic constrained property models using geostatistical inversion captured distinctively the heterogeneity and small scale variations in the interwell region.
Rapid Identification of Oil‐Contaminated Soils Using Visible Near‐Infrared Diffuse Reflectance Spectroscopy
Authors: Chakraborty Somsubhra , Weindorf David C. , Morgan Cristine L.S. , Ge Yufeng , Galbraith John M. , Li Bin , Kahlon Charanjit S.
Published: July 2010

In the United States, petroleum extraction, refinement, and transportation present countless opportunities for spillage mishaps. A method for rapid field appraisal and mapping of petroleum hydrocarbon–contaminated soils for environmental cleanup purposes would be useful. Visible near‐infrared (VisNIR, 350–2500 nm) diffuse reflectance spectroscopy (DRS) is a rapid, nondestructive, proximal‐sensing technique that has proven adept at quantifying soil properties in situ. The objective of this study was to determine the prediction accuracy of VisNIR DRS in quantifying petroleum hydrocarbons in contaminated soils. Forty‐six soil samples (including both contaminated and reference samples) were collected from six different parishes in Louisiana. Each soil sample was scanned using VisNIR DRS at three combinations of moisture content and pretreatment: (i) field‐moist intact aggregates, (ii) air‐dried intact aggregates, (iii) and air‐dried ground soil (sieved through a 2‐mm sieve). The VisNIR spectra of soil samples were used to predict total petroleum hydrocarbon (TPH) content in the soil using partial least squares (PLS) regression and boosted regression tree (BRT) models. Each model was validated with 30% of the samples that were randomly selected and not used in the calibration model. The field‐moist intact scan proved best for predicting TPH content with a validationr2of 0.64 and relative percent difference (RPD) of 1.70. Because VisNIR DRS was promising for rapidly predicting soil petroleum hydrocarbon content, future research is warranted to evaluate the methodology for identifying petroleum contaminated soils.
Oxidative dehydrogenation of isobutane over supported V-Mo mixed oxides
Authors: Mitran Gheorghiţa , Marcu Ioan-Cezar , Urdă Adriana , Săndulescu Ioan
Published: July 2010

Vanadium-molybdenum oxides supported on Al2O3, CeO2 and TiO2 were prepared by a ?wet? impregnation method, characterized using DRX, N2 adsorption, UV-Vis spectroscopy, electrical conductivity measurements and tested in the oxidative dehydrogenation of isobutane. The catalytic performance in the oxidative dehydrogenation of isobutane at 400-550?C depended on the nature of support and on the content of VMoO species on the support. The catalysts supported on alumina were more active and selective than those supported on ceria and titania.