bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-Stage Acid Stimulation Improves Production Values in Carbonate Formations in Western Canada
Authors: Baumgarten Dan , Bobrosky Doug
Published: May 2009

Over the past few years, a new multi-stage, multi-jet fracturing technology has improved the acid fracturing of the Wabamun formation located in south central Alberta.

The Crossfield member of the formation, found in the Swallwell field, has a large original oil and gas reservoir with low recovery factors to date of 2.4% for oil and 5.2% for natural gas. A 1% increase in recovery factors would yield an additional 875,000 bbls and 851,000 mcf of gas.

Use of multiple mechanical isolation points in the new technology has demonstrated average initial production increases of 77 to 102% and final production increases of 12 to 28% compared to historical wells. The micro to very fine crystalline dolomite of the Crossfield member has average permeability ranges from 0.1 and 0.3 mD; therefore, acid stimulation is required in order to economically extract the resource.

This paper will discuss the planning and design processes that led to the implementation of the multi-stage, multi-jet technology. It will outline the lessons learned during deployment of the completion, and will highlight the stimulation treatment execution and post-stimulation results. The text will detail examples from the case studies and will outline the benefits of this technology.
Minimizing Dynamic Dysfunctions Sets New Drilling Performance Benchmark in Saudi Gas Application
Authors: Brackin Van , Doster Mike , Mounzer Fadi , Alfonzo Luani
Published: May 2009

The myriad drilling problems associated with dynamic dysfunctions, including substandard performance and premature bit and downhole tool failure, have been well documented in the literature. Alleviating these problems and potential failures requires a systems approach that brings together improvements in the bit, BHA, and operating practices.

This paper describes one such approach where a new-generation 16-in. PDC drill bit was applied in tandem with a newly engineered 12 ¾-in. positive displacement motor (PDM) and hard rock drilling techniques. Further, the high RPM and low weight-on-bit (WOB) recommendations inherent in old-school shale drilling gave way to hard rock parameters that maximized depth of cut. Consequently, impact fractures and abrasive wear were reduced, thereby maintaining the bit in an overall sharper and more efficient condition. Through this systems approach, the operator successfully avoided premature bit and motor damage and achieved record ROP and reduced costs in a Saudi Arabia project.

Historically, most sections have required a cleanout run with a roller cone bit, followed by a PDC bit for drilling the first 4,800 ft, and another PDC bit to complete the interval. The combination of the new tools and precise drilling techniques has eliminated the complexity and costliness of such runs. In a rare shoe-to-shoe run, the combination drilled out the 18 5/8-in. casing to TD at a record ROP of 33.8 ft/hr, replacing the three planned bit runs and saving the operator US $249,000.

The authors will explain the advances in PDC bit technology that focused on minimizing cutter damage, thus allowing bits to drill further at faster ROP. Further, they will examine ongoing initiatives aimed at improving performance and reliability in demanding drilling conditions that resulted in the development of the new and more robust PDM that provides higher torque output at available flow rates and pressures. They will describe how the new PDC bit technology and higher torque PDMs, combined with a change in operating procedures that focused on minimizing dynamic dysfunctions, resulted in a step change in performance.
Experimental and Numerical Study on Production Performance: Case of Horizontal and Dual-Lateral Wells
Authors: Amro Mohammed M. , Benzagouta Mohamed S. , Ayyad Hazim A. , Hussain Mofazzal
Published: May 2009

Current drilling technology is moving towards maximum reservoir contact (MRC) by means of extended-reach horizontal and multilateral wells in all types and shapes. Horizontal and Multilateral applications become more commonplace to improve the well productivity by providing maximum reservoir contact, minimizing operating costs, lowering the pressure drawdown and maximizing profitability. This paper presents the results of a numerical study performed to determine the production performance of dual opposed laterals compared to horizontal wells. With a total section exposed to the reservoir equal in both types, an experimental model has been built for the purpose of studying the production performance of the abovementioned well configurations. Production performance, in both systems, has been compared using numerical and physical model.

Results have proven that the dual-lateral well configuration accelerates the oil recovery by 90% in the early stage of production, compared to the horizontal well. Thus, the oil recovery using dual-lateral remains higher than that of horizontal well as water cut increases. Production performance for both configurations becomes equal in case of complete water production.

However, the numerical model shows that the dual-lateral accelerates the oil recovery by 10% compared to the horizontal well performance. Nevertheless, the results of the experimental runs indicate higher recovery values at early production stage compared to the numerical mode results. Such results confirm that dual-lateral wells are more efficient compared to the horizontal wells, where the optimum horizontal length is exceeded. Details of the optimum horizontal well length are presented. The paper provides also advantages of drilling dual-lateral wells compared to the horizontal wells exceeding the optimum lengths.
Production Enhancement of Cased-Hole Wells Using Mesophase Fluids
Authors: Christian Chad F. , Quintero Lirio , Clark David E. , Jones Tom A.
Published: May 2009

Formation damage is a by-product of the drilling, completion and production process that can be attributed to many factors. In cased-hole wells, the reservoir pressure and hence hydrocarbon flow may be impeded by various damaging mechanisms caused by the drill-in fluid filtrate, in-situ emulsions, water block, and organic deposition.

Mesophase chemistry has been developed to remove near-wellbore skin damage in perforated cased-hole applications. This fluid chemistry can be utilized as a perforating fluid and/or be applied during remediation operations to remove the formation damage around the perforation tunnels and/or fracture channels. The physical properties of this mesophase fluid include high oil solubilization, high rates of diffusion through porous media, and the reduction of interfacial tension to near zero between organic and aqueous phases, making them excellent fluids for removing formation damage.

This paper presents the development and case histories from numerous field applications that demonstrate the efficiency of mesophase chemistry to reduce skin damage and improve well productivity.
Successful Utilization of Fiber Optic Telemetry Enabled Coiled Tubing for Water Shut-off on a Horizontal Oil Well in Ghawar Field
Authors: Al-Zain Ahmed , Duarte Jorge , Haldar Surajit , Driweesh Saad , Al-Jandal Ahmed , Shammeri Faleh , Bugrov Vsevolod , Sarfraz Tashfeen
Published: May 2009

Water control is the key to prolong well life for economical and efficient oil recovery. When water reaches certain levels, oil production profitability decreases dramatically and even goes to negative. One feasible option in this case is a rigless water shut-off treatment, which involves an intensive process, starting from candidate selection and finishing with post-treatment well performance analysis. This kind of operation becomes more challenging for horizontal wells with open hole completion. Well A, a horizontal open hole producer with 2,440 ft of reservoir contact, was drilled and completed in November 2000. The last well production profile was determined by a Flow Scan Image (FSI) log, which showed 51% of water cut and the entry of most of the water was from the toe of the horizontal section. Based on economical and technical feasibility, fiber optic telemetry enabled coiled tubing (CT) was selected for an accurate and effective way to isolate the water producing interval, reduce water cut and enhance oil production.

The advanced and intelligent CT enables real time downhole measurements via fiber optic telemetry system. The system consists of surface readouts including dynamic interpretation software, fiber optic cable, and bottom-hole sensors, which provides Casing Collar Locator (CCL) readings, Distributed Temperature Survey (DTS), temperature, internal and external CT pressure measurements. Permanent zonal isolation, utilizing an inflatable packer with a cement plug above the packer, was successfully performed using CT conveyed fiber optic system. The availability of CCL, temperature and differential pressure readings enabled precise depth control, proper packer inflation and optimization of the cement design.

This paper highlights the application of a CT equipped with fiber optic advanced technology on a rigless water shut-off job. The paper also discusses the water shut-off (WSO) job design and execution challenges.
Differentiating Well Placement Expectations in Saudi Arabia with Production from Stringer Sand Reservoirs
Authors: Warran Phil , Mishrafi Nidal , Dossari Saleh M. , Butt Parvez J. , Javalagi Mohan , Jawad Waleed
Published: May 2009

Saudi Arabia is blessed with the world's largest onshore and offshore reservoirs. Currently Saudi Aramco is aggressively pursuing production increment ventures, one of the main components being the development of stringers which are present among all the major offshore oil fields. One of the technology contributions to Saudi Aramco's effort is proactive geo-steering using Directional and Deep Resistivity technology to maximize the net sand delivered from each well.

The drilling of development wells in sand stringers involves very thin and sinuous targets. These targets are the channel sand stringers and contain a substantial amount of hydrocarbons. Optimal well placement is a requirement for these very thin reservoirs in order to drain them in a cost effective manner.

Conventional well placement has met with limited success in stringers and thus resulted in low production figures. PeriScope has persistently proven that a proactive well placement technology can be translated into maximum reservoir contact, minimum well-bore tortuosity and a facilitator for optimal production.

Due to the uncertainty that is inherently present in the distribution of the channel sands, the prediction of the azimuth of channel meander can now be confidently solidified with new deep and directional electromagnetic measurements. By detecting the upper and lower conductive shale boundaries the wells can be steered in this very challenging environment of channel sands.

In the past two years Directional and Deep resistivity technology has delivered over 110,000ft of challenging reservoir to Saudi Aramco. This has also been an enabler for multi-segment collaborations and is now seen as a premium well placement service within Saudi Arabia. This paper will highlight how these innovative technologies have impacted the stringer sand reservoir development in multiple offshore oil fields of Saudi Arabia.
Cleanup of Oil-Based Mud Filter Cake Using an In-Situ Acid Generator System by a Single-Stage Treatment
Authors: Binmoqbil Khalid H. , Al-Otaibi Msalli A. , Al-Faifi Mohammad G. , Al-Khudair Waleed S. , Al-Aamri Ali D.
Published: May 2009

Near-wellbore formation damage is expected during the drilling operations. Minimization, prevention, and removal of near-wellbore damage are essential to maximize well productivity. One of the major sources of skin damage is the residual filter cake developed by reservoir drill-in fluid (DIF). Therefore, an efficient filter cake cleanup method should be considered to enhance well productivity. Oil producers in sandstone reservoirs are being drilled with invert emulsion DIF during oil reservoir drilling. Standard completion of oil wells is with stand-alone screens. Although screens stabilize the wellbore and address sand control issues, it can also act as a trap for filter cake, resulting in high drawdown pressure. An in-situ acid-precursor technology, which generates organic acid, was proposed to be used. The prime advantage of this technology, especially in long horizontal wells, is the uniform distribution of acid during precursor to remove oil-based mud (OBM) filter cake by a single-stage. A special surfactant blend was incorporated in the cleanup fluid to alter the wettablity of the oily filter cake, and therefore, facilitate the reactivity of the produced acid with calcium carbonate particles. Detailed lab studies were conducted to evaluate the efficiency of the in-situ acid generator technology. The lab studies include various tests to evaluate filter cake removal efficiency, return permeability on real core samples, compatibility with formation fluids, and strength of dissolving calcium carbonate particles. Based on lab results, it was recommended to spot the single-stage filter cake cleanup fluid as a treatment for an oil well. This paper will discuss in detail the laboratory work that was conducted to evaluate the filter cake cleanup fluid performance.
Case Study: First Successful Offshore ESP Project in Saudi Arabia
Authors: Al Zahrani Ahmed R. , Al-Nasser Redha H. , Collen Timothy W. , Khade Sudhakar
Published: May 2009

The Electrical Submersible Pump (ESP), a form of artificial lift technology, has proven to be a durable solution for delivering the required rates from Saudi Aramco fields. Therefore, this form of artificial lift was selected to increase production rate from one of the offshore fields, while optimizing offshore producing facilities. This offshore field has favourable conditions for ESP application, producing from carbonate reservoir with no anticipated fines production, low GOR, low temperature, low bubble point pressure and high API gravity.

All new installations were carried out without interrupting the ongoing production target. The project has completed a four-years operating cycle while continuously maintaining the field production rate with an acceptable ESP failure and run life.

So far, 41% of the originally installed ESP systems are operating more than 4 years and 20% are operating in the range of 3-4 years run life. The cumulative average run life of operating ESPs is 2.7 years and that of failed ESPs is 1.74 years. To maintain required production target, an effective ESP replacement program is a core element of field production strategy. Therefore, several measures such as replacement of underperforming ESP systems and upsizing of the pumps have been implemented. Furthermore, Dismantle Inspection and Failure Analysis (DIFA) of pulled ESP systems were conducted to evaluate the root cause of the failures and remedial actions were implemented to prevent such occurrences in future. Increasing Motor Lead Extension cable thickness, utilization of tandem seals and new wellhead penetrators are also expected to further enhance the ESP run life.

New applications to minimize ESP failures due to human intervention and ensure proper equipment handling during installations are being pursed. In addition, tandem ESP completions and different types of wellhead penetrators are being pursued to reduce rig utilization, increase producing life and minimize failures.
Gel under Dynamic Stress in Porous Media: New Insights using Computed Tomography
Authors: Al-Muntasheri Ghaithan A. , Zitha Pacelli L. J.
Published: May 2009

Crosslinked polymer gels are widely utilized to reduce water production from oil and gas producing wells. Zitha et al. (2002) developed a theory accounting for the basic mechanisms of gel extrusion by water through matrix porous media, i.e., compression, yield and flow. Their model predicted pressure drop and saturation changes over the gel-treated porous media during gel yield and extrusion by brine. The pressure drops were successfully compared to yield and displacement of an organically crosslinked gel formed insitu by water from Berea sandstone cores. This paper reports for the first time the measurements of saturation changes during such yield, and displacement experiments using X-ray Computed Tomography (CT) scanning. The experiments were performed using Bentheimer sandstone cores treated with gels containing 3 wt% polyacrylamide polymer (PAM) and 2 wt% polyethyleneimine crosslinker (PEI) shut-in at 55°C (131°F) for 22 hours under high pressure drops up to 89 bars (1,291 psi). Total organic carbon analyses indicated that no polymer retention or adsorption took place during gelant placement into Bentheimer sandstone cores. CT images indicated that the displacing brine saturations were independent of position, although, saturations increased with time. In addition, the breakthrough pressure occurred at a relatively later time compared to the critical pressure. New insights into the existing saturation models are given, which will provide a better understanding of the pressure and saturation changes with time.
R&D Role for Sustainable Production Operations
Authors: Guerillot Dominique R. , Al-Taie Ihsan , Pauchard Vincent , Raju Krishnam , Sanders Peter , Sherik Abdelmounam , Vilagines Regis
Published: May 2009

This paper reviews some of the Saudi Aramco R&D Projects for increasing the asset life expectancy of its production facilities. The ultimate objective is to deliver innovative solutions to address actual or anticipated problems encountered by operations. The Research and Development Center in Saudi Aramco has developed a generic delivery model consisting, for each project, of the identification of the following four main components: business need, value created, internal competencies and partners to provide solutions in a timely manner

The portfolio for the Upstream R&D Program for the production facilities is composed of several projects: The Crude Oil Separation project to improve the separation of the production into oil, gas and water phases.The Emulsion Mitigation project to handle specific problems related to emulsion from the near wellbore to the separation vessels included.The Water Systems project built with a holistic approach, to handle produced and injected water, and associated phenomena such as bacterial control and corrosion.The Scale Mitigation project to prevent and mitigate scale in oil and gas wells, for better injectivity and productivity.The Pipeline Integrity project, which includes a variety of issues such as sulfur deposition and blister control.The Black Powder Management project, a multi-disciplinary project to address this specific issue caused by corrosion for sales gas pipelines.

This paper will summarize the goals and deliverables of these projects. Further potential R&D projects for Production or Midstream related issues are also listed.
Horizontal Open Hole, Dual-Lateral Stimulation, Using a Multilateral Entry with High Jetting Tool
Authors: Amorocho Jose R. , Solares J. Ricardo , Al-Mulhim Abdulmohsin , Al-Saihati Ali , Kharrat Wassim
Published: May 2009

The number of multilateral gas producers drilled in the Ghawar field has significantly increased over the past few years as part of the reservoir development strategy to maximize well productivity through maximum reservoir contact. Although these wells are expected to require little rigless intervention to conduct surveillance or productivity enhancement work, the effective options available to selectively access each of the laterals are limited. Thus specialized tools and techniques are required but the complex nature of these deep wells, combined with the high pressure and temperature characteristics of the reservoir, makes their application difficult and the outcome of the well intervention procedures uncertain.

One of the techniques that has proven successful in different fields around the world, is the use of a lateral accessing tool to selectively access the desired lateral to then perform a stimulation treatment, run a production log, or any other operation. Combining lateral accessing and high-pressure jetting tools to access and stimulate two under-performing laterals a world first, was done in Well A, a producer drilled in a carbonate reservoir in Saudi Arabia's Ghawar field. The stimulation treatment was successful and the well achieved a two-fold rate increase.

This paper provides details about the pre-job research and testing conducted, the methodology, equipment and procedure successfully applied in dual-lateral Well A, and lessons learned throughout the operation. The post-treatment performance of the well was better than anticipated, which encouraged Saudi Aramco to further utilize the technique for different applications.
Use of Auto Diverter Valves in ESP Completed Oil Wells Which Produce Sand and Solids
Authors: Sipra Iqbal , Shotter Paul
Published: May 2009

This paper is intended to present the experiences of PDO Oman using Pumptools’ ADV valves (Automatic Diverter Valve) in ESP completed wells that have sand and solids production. Short run times were repeatedly experienced in Oman due to the sand and solids falling back on top of the pump after the ESP had been switched off or tripped. Upon restart the sand plug on top of the pump caused damage and premature failure of the ESP.

The Pumptools Patented ADV was designed from the outset to address these route cause issues which have plagued ESP users for many years. This new technology tool is designed to enhance the run time of ESPs in sandy wells. The Tool was used in several fields in Oman where sand was being produced. This paper outlines the improvements seen as a result of utilizing the Pumptools Auto Diverter Valve (ADV).
Smart Well Production Optimization Using an Ensemble-Based Method
Authors: Su Ho-Jeen
Published: May 2009

Recently, the ensemble Kalman filter method (EnKF) has been successfully applied in assisted history matching. It is a very powerful tool and can handle a very large number of reservoir parameters, up to millions. The method is a Monte Carlo type formulation, and employs a covariance matrix and maximum a posteriori estimate theory. This new technology has been implemented into an industrial parallel reservoir simulator.

In this paper, we show its application to optimize two horizontal wells equipped with an inflow control valve (ICV) in a sector model of 200,000 cells. One hundred layers were used to capture geological heterogeneity. The two wells were drilled parallel to the edge-water boundary. The optimization objective is to minimize cumulative water production over a 10 year production period.

Encouraging results have been obtained. Cumulative water production was reduced 50% after only five optimization iterations. The optimized ICV opening variation over the entire production history is described. Verified by simulated water production results, the ensemble method did a satisfactory optimization job, better than a trial and error approach could provide. The fully-automated optimization process can be completed within a few hours under a parallel computing environment.
Development of Generalized Porosity-Permeability Transforms by Hydraulic Units for Carbonate Oil Reservoirs in Saudi Arabia
Authors: Shenawi Shamsuddin , Al-Mohammadi Hisham , Faqehy Muteb
Published: May 2009

There are several types of porosity-permeability transforms to determine permeability from well log-derived porosity in uncored oil and gas wells. Widely used typical transforms, either by geologic zones or by facies, do not provide satisfactory permeability to be distributed in reservoir simulation models. Hydraulic Unit (HU), which is a technique of rock typing of reservoir, provides far superior transforms than typical transforms. In this work, available routine core data, from major carbonate oil reservoirs located in eight different oil fields of the Kingdom of Saudi Arabia, are assembled to develop improved generalized porosity-permeability transforms by Hydraulic Units (HU).

Improved transforms by HUs were developed for major carbonate oil reservoirs in eight different oil fields. Correlation accuracy (R2) of each transform by HU was very good (>0.9). Then all data from eight different fields were combined to develop generalized transforms by HU technique. This technique provided excellent transforms for various HUs regardless of rock fabrics—either limestone or dolomite.

Developed generalized transforms by HUs were tested for their accuracies on acquired core data in two wells, completed in the same major carbonate reservoir, but in two different oil fields. Applicability of generalized transforms was also tested with the core data from a different secondary carbonate reservoir. Calculated permeability by HUs matched very well with the tested core data which enhanced the reliability of developed generalized transforms.

Similarly, generalized vertical permeability transforms by HUs were developed for the same major carbonate reservoirs in eight fields. Calculated vertical permeability by HUs matched very well with core data as well. Then vertical to horizontal permeability ratios (kV/kH) by HUs were calculated using both generalized transforms for vertical and horizontal permeability. The kV/kH ratios for most of the HUs are found to be almost one under the laboratory condition.
Model Ranking and Optimization of Fractured Reservoir Using Streamline Simulation, Case Study a Gas Condensate Reservoir
Authors: Askari Amir Abbas , Bashiri Golamreza , Kamali Mohammad Reza
Published: May 2009

Nowadays the oil and gas industry is increasingly facing the difficulties associated with fields characterized by the presence of natural fractures. These difficulties are due to uncertainties in geological model especially in the fracture distributions. To successfully address these challenges, it is paramount to improve the characterization and simulation of those reservoirs. This can only be performed through the fully integration of all available data for generating stochastic DFN model and then using streamline simulation approach for fast history matching.

In this paper, using interpretation of image logs closely was related best productive zones with open fractures and then their correlation with other parameters (including lithology and petrophysical logs) were determined through reservoir. Three main fracture direction set were defined by fold-related fractures. A discrete fracture network (DFN) was generated using inferred parameters from outcrops, FMI logs and cores. Then, permeability of DFNs developed was calibrated with available well test permeability. After that, a streamline simulation due to high computation speed, high accuracy and good visualization was used to repeated history matching multiple equi-probable of a dual porosity model in gas condensate reservoir. So, with running streamline simulation, three realizations (High, Medium and Low) ranked based on the objective function values. In final, comprehensive history matching will be done as optimally for the three-selected realizations.

The overall goal in this study was to develop representative fluid flow simulation model for reservoir management as gas cycling scheme in enhanced condensate recovery. This method due to using actual fracture parameters has great application in the high resolution fractured reservoir modeling for model ranking, screening and optimum dynamic model calibration for reduction of the history matching effort without fabricated by reservoir engineer.
Fracture Lineament Validation using Streamline Simulation in a Giant Middle East Field: An Innovative Approach
Authors: Al-Najem Abdullah A. , Al-Thuwaini Jamil S. , Al-Omair Abdulatif , Jilani Syed Z.
Published: May 2009

With the advancement in streamline simulation technology in modeling fractured reservoir and streamline associated well allocation factors, now it can be used as an effective tool to validate fracture lineament through visualization of streamline-based flow pattern and injection allocation between each injector and producers. Such capability has made streamline based history matching very attractive and more reliable in expediting history matching of simulation project.

The objectives of the study are to improve the history match by validating fracture lineaments and then optimize Injection-Production Ratio (IPR). This study involves the conversion of a finite difference black oil Dual-Porosity Dual-Permeability (DPDP) history matched model into a Dual-Porosity Single-Permeability (DPSP) streamline simulation model and history match results are improved. Based on field-wide streamline flow patterns map, the field is divided into several independent regions. Within these regions, the fluid flow patterns between individual producers and injectors are also identified by the generated streamlines. In addition, an injector efficiency software is used to calculate actual water contribution of each injector to each producer from the well allocation file generated by the streamline simulator.

This paper documents the procedure on imporoving water cut matches by validating fracture lineaments. This novel procedure involves the tracking of water saturation and Time of Flight (TOF) of injected water along streamlines, its respective main contributing injectors, fracture/matrix cells carrying the flow, fracture cells to be connected and/or disconnected with other fracture cells and where fracture/matrix cells require permeability enhancement or reduction.

After improving the history match level, Injection Production Ratios (IPR) are optimized and considerable amount of incremental oil production is obtained.
The Use of Capacitance-Resistive Model for Estimation of Fracture Distribution in the Hydrocarbon Reservoir
Authors: Delshad M. , Bastami A. , Pourafshary P.
Published: May 2009

Capacitance-resistive model is a new method to quantify communication between vertical wells in a reservoir. This method is based on the contribution of each injector on each producer. Capacitance-resistive method uses production and injection rate data to develop and calibrate a model to predict the future performance of the producer wells. The proposed procedure uses a nonlinear signal-processing model to provide information about the connectivity between wells and presence of flow barriers and fractures.

In this paper, we present a new method to estimate the fracture distribution in the reservoir using Capacitance-resistive model.

We focused on the analysis of the relation between each injector/producer pair. We analyzed the connectivity weight factor of each injector and the neighboring producers to quantify the fracture distribution at each section of the reservoir. Hence, the developed model provides the fast estimation of the fracture distribution using only the flow rate data.

The developed model has been tested for different synthetic fractured reservoir case studies. The results are in good agreement in comparison with the fine grid numerical simulation results. It showed that our new approach has the capability to compute the fracture distribution much faster and cheaper than the numerical simulations.

By the new developed model, it is possible to estimate the fracture distribution easily and accurately in reservoirs, which has an important role in the field development, drilling new wells and future injection schedule.
Minimum Miscibility Pressure Determination for Systems Carbon Dioxide + Heavy Hydrocarbon (N-Eicosane) + Light Gas (Ethane or Propane) Using Peng-Robinson Equation of State
Authors: Al-Marri Salem S.
Published: May 2009

An important parameter used to determine the feasibility of miscible displacement is the minimum miscibility pressure (MMP). In oil recovery, gas injection can be a very efficient method for improving the productivity of the wells, particularly in the case when miscibility develops during the displacement process. Extensive use of carbon dioxide mixed with light hydrocarbon such as ethane and propane for this purpose has the secondary benefits of being a temporary means of sequestering these green house gases. MMP at which a gas should be injected into the reservoir in order to obtain a multicontact miscible displacement has consequently attained a very important status in enhanced oil recovery studies. MMP can be estimated from phase equilibria data using pseudo-ternary conceptualization of Benham et al. The full advantages of the use of carbon dioxide as a selective solvent can only be realized through knowledge and understanding of its phase behavior and equilibria with different hydrocarbons. In this paper binary and ternary phase equilibrium studies involving a heavy hydrocarbon such as n-eicosane, light hydrocarbon such as ethane and propane with carbon dioxide was performed. Peng-Robinson equation of state with binary interaction parameters were applied to represent vapor-liquid equilibria and to optimize the representation with minimum use of ternary parameters. The experimental data obtained was used to predict the MMP using pseudo-ternary conceptualization of Benham et al. and examine its variation with nature and amount of light hydrocarbons in the injected gas.
Integrating Reservoir Characterization and Fracturing Analysis to Understand the Pressure Transient Response of Frac Packed Wells
Authors: Al-Naimi Khalid , Al-Thawad Faisal , BinAkresh Saud , Bartko Kirk
Published: May 2009

The Unayzah-A in field T is an Aeolian sandstone formation with high sanding tendency requiring stimulation using the frac pack technique. Modified Isochronal Tests (MIT) and pressure buildups (PBU) were conducted on several wells in field T, to assess the reservoir and to evaluate the frac pack technique. During the analysis of the MITs and PBUs, several consistent trends were observed in the pressure derivative plots of field T wells, such as the absence of the fracture signature and the decrease of reservoir quality away from the wellbore. This consistency in the behavior of the pressure derivative was investigated in this study. Analytical and numerical well testing models, reservoir characterization, and fracturing analysis assisted in investigating the observations in PBUs. The investigation showed that to capture a fracture in the pressure derivative plot of high permeability formation, the fracture half length has to be extremely long, and there should be significant contrast between the fracture and the formation conductivities. The investigation also showed that the created fracture and the reservoir heterogeneity due to changes in geologic facies dictate the shape of the pressure derivative plot.

This paper will discuss how the reservoir characterization and the fracturing analysis were used to help in analyzing the pressure transient response of frac packed wells. Two pressure buildups (PBUs) and four MITs were used in this study. This paper will also shed some light on the frac pack results, and the non-Darcy flow effect.
Productivity of Fractal Reservoirs
Authors: Jelmert Tom Aage
Published: May 2009

A fractal reservoir may be thought of as having a spatial dimension that falls between the Eucledian space dimensions 1, 2 and 3. This concept may be unfamiliar to many. The objective of this study is to show that a model based on a fractal concept may be a useful complement to conventional models. To this end we investigate the productvity of wells in fractal reservoirs. The productivity index has a clear economic significance. Unfamiliar ways of characterizing rock properties are discussed by use of simplified models.

For clarity, we discuss steady state flow in a naturally fractured reservoir. A steady state condition depends on a constant pressure outer boundary. We investigate analytical solutions. These include the conventional ones as special cases. The application of the proposed solutions will be in well testing, estimation of natural flow, economic modelling and reservoir characterization.

The fractal model leads to rock properties of powerlaw dependence on the spatial variable. We find that this description may reflect the length scale of the elementary volume, REV. Fracture architecture; changing flow area and stress sensitivity may also contribute to powerlaw dependency. The analytical solutions obtained are valid for any reservoir that may be characterized by simple powerlaw expressions whether fractal or not.

We find that equation for the flow efficiency of a fractal reservoir depends on three dimensionless parameters. The flow efficiency is sensitive to a parameter (the difference between the fractal dimension and the conductivity index), dimensionless distance and skin.
Performance of Thermal Recovery Processes in a Middle Eastern Reservoir
Authors: Algharaib Meshal , Alajmi Abdullah , Gharbi Ridha
Published: May 2009

Primary oil recovery is usually very low which leaves large quantities of oil retained by capillary and viscous forces. Enhanced Oil Recovery (EOR) techniques are used to recover these retained hydrocarbons volumes. Thermal recovery is an EOR technique which is usually used to enhance oil production from heavy oil reservoirs. In thermal recovery methods, hot fluids, such as steam or hot water, are injected into hydrocarbon strata to reduce the retaining forces responsible for oil entrapment and enhance recovery efficiency. In Middle East, heavy oil deposits are encountered in many countries. The maturity status of the current major oil producing fields in addition to the current high energy demands are main contributors to the current interest in developing heavy oil resources. Therefore, the need to predict the performance of thermal EOR processes in these heavy oil accumulations is of a major importance.

The targeted reservoir in this study occurs at shallow depths, ranging from 500 – 1000 feet and is widely spread. Apart from two cyclic steam stimulation pilots conducted during the 80';s, this reservoir was left undeveloped for the past years due to the high sulfur content and extraction cost. The findings of these pilots indicate the suitability of this reservoir to thermal recovery methods. In this paper, the performance of hot water flooding, in a sector area of the targeted reservoir is simulated under different well arrangements. Various reservoir/design parameters were considered to evaluate the cumulative oil recovery in terms of the cumulative heat injected. The results show some cases where the economics of thermal recovery applications can be improved by a proper heat management. Moreover, the paper highlights the functional relationships between cumulative oil recovery and cumulative heat injected under the investigated reservoir/design parameters.
Optimal Transformations for Multiple Regression: Application to Oil Viscosity Correlation Above and Below Bubble Point Pressures
Authors: Al-Marri Salem S.
Published: May 2009

Reservoir oil viscosity is one of the important reservoir fluid properties used for many petroleum engineering calculations such as evaluating hydrocarbon reserves, planning enhanced oil recovery methods, calculating fluid flow rate through reservoir rocks, etc. Therefore, achieving an accurate reservoir oil viscosity value is very crucial for petroleum engineers. Viscosity of reservoir oil can be obtained by a laboratory measurements and empirical correlations. Many of the common correlations in use were developed using data collected from different regions of the world.

The literature contains many different viscosity models, the viscosity models found in the literature range from highly theoretical to simple empirical correlations. Two typical viscosity correlations are applicable to both liquid and gas phases; the Corresponding States Method (CSM), semi-empirical, and the empirical Lohrenz-Bray-Clark (LBC) method. In this paper, the applicability of both models were tested to predict the experimental viscosity measurements for pure n-eicosane, ethane/n-eicosane, propane/n-eicosane binary systems. After normal quality checks, nonlinear multiple regression with linear partial correlation coefficient techniques were applied to develop friction theory and binary interaction parameter were used to modify the representation of friction theory model. The comparisons among LBC, Corresponding State Principle (CSP), general model of friction theory and modified friction theory (using binary interaction parameter) were performed. Based on the error statistical analysis results, the developed friction theory model has shown to provide accurate estimates of viscosity in all pressure regimes.
Practical Application of CFP Technology to Resolve Complex Near Surface Problems and to Estimate Velocity-Depth Model
Authors: Almomin Ali , El-Marhfoul Bouchaib
Published: May 2009

Complex topography and highly variable weathering layers in the near surface can severely degrade the quality of seismic data and result in a distorted structural image of the deeper subsurface reflectors. The objective of this work is to compare seismic image quality after application of the Common Focus Point (CFP) redatuming with images generated using more conventional static techniques. The CFP method resolves near surface effects on seismic data by considering the wave propagation phenomena, based on data-driven focusing operators, independent of any velocity model.

Focusing operators are required to describe the kinematic phenomena of the wave field as it passes through the near surface. The focusing operators are automatically estimated using a parametric inversion procedure that assumes the focusing operators can be described with a smooth parameterization. Using these operators, a complete wave field redatuming can be performed moving the data recorded at the surface to a new datum underneath the complex near surface. The results represent data as it would have been measured underneath the complex near surface, with the sources and receivers on the datum reflector. In a second step, these focusing operators can be input to a tomographic inversion process to obtain a velocity-depth model. This model can then be used for converting the redatumed results to depth.

The results from the CFP-based redatuming showed significant improvements over results from traditional statics methods for both synthetic and real data. The continuity of the deeper reflection events was improved and a more reliable time image was obtained of the deeper structure.
Advanced Processing of Walkaway VSP Data, Offshore India
Authors: Jindal Nidhi , Jyothi Prativadi , Tiwari Sanjay , Biswal Ajoy , Sanghvai Pranaya , Barakat Saleh
Published: May 2009

Walkaway VSP (WVSP) data plays a major role in reservoir delineation and characterization. High-resolution VSP data can be integrated with surface seismic data to provide detailed descriptions of formation properties and identification of reservoir compartments, which are not possible with surface seismic data alone. This present study is from an area in the deep water of the Krishna-Godavari basin. Advanced processing of deep water WVSP data has been done to delineate the small scale faults, if any, which may interfere with the fluid flow and cannot be clearly visible on surface seismic data and to understand compartmentalization and fluid continuity within the zone of interest.

From the WVSP pre-survey modeling, 28 geophone levels at 10 meter receiver spacing and 2 profiles of 8 km. length were designed. A vector migration algorithm was applied to image the 3 component VSP data, to enhance the image quality. Multiple-View migration has been applied, which produces a much wider image zone then conventional VSP migration using primary reflections only.The image result presented in this paper shows how the walkaway VSP is able to identify detailed stratigraphic and structural geological features with greater resolution than surface seismic data.
Lessons Learned from 100 Intelligent Wells Equipped with Multiple Downhole Valves
Authors: Mubarak Saeed , Dawood Naseem , Salamy Salam
Published: May 2009

The last decade has been marked by the emergence of intelligent field technologies. Many E&P companies have moved from the piloting and trial-testing mode towards strategic implementation demonstrating that these technologies have shown their capabilities. While the current deployment of these technologies represents only a small fraction of the overall installation, the trend is indicative of the shifting of attitudes and preferences within companies. Among those companies, Saudi Aramco has deployed fit-for-purpose technologies such as intelligent wells equipped with multiple downhole valves, as part of its best-in-class practices (Figure 1). Continuous assessment of these technologies is important to provide reassurance on their values.

The resulting performance of this technology is a function of multiple factors spanning from reservoir parameters, completion schemes to surface infrastructure. Understanding and assessing the impact of these factors is complex due to the wide variation of variables.

This article summarizes the lessons learned from more than one hundred deployments in wells equipped with multiple downhole valves. These lessons illustrate the advantages of these applications and should provide insight for improved performance. As there is no "one size fits all," then proper design should be emphasized for maximum effectiveness.
Materials Selection for Smart Well Completions in Conjunction with Expandable Casing Technology
Authors: Choi Ho Jin
Published: May 2009

Materials selection is critical to ensure the life expectancy and cost-effectiveness of smart well completions in conjunction with expandable casing technology in Saudi Aramco re-entry multilateral oil wells for effective hydrocarbon recovery. Linking these two leading-edge technologies, Saudi Aramco has successfully completed more than 20 oil producing wells since 2004. Knowing well corrosivity and corrosion resistance of materials is critical in selecting cost-effective downhole equipment. This paper proposes a guideline for materials selection of downhole production tubing in oil and gas producing re-entry wells for maximum reservoir contacts, based on results of field and laboratory corrosion studies in sweet and sour services.
First Saudi Aramco Use of Retrievable Downhole Pressure and Temperature Gauges Monitoring System: A Cost Effective Technology Solution to Manage Maturing Oil and Gas Fields
Authors: Chatriwala Shaizad A. , Al-Subaie Fehaed M. , Al-Shehri Dhafer A. , Soremi Adeyinka X. , Reaux James
Published: May 2009

The trial test of Wireline Retrievable Side Pocket Surface Read-Out Permanent Downhole Monitoring System (SPSRO-PDHMS) was successfully conducted in a newly drilled well in a giant oil field in Saudi Arabia. In the wireline retrievable PDHMS system, the downhole gauges sit in a side pocket mandrel; if the downhole gauges malfunction, they can be retrieved and replaced easily with wireline. Conventionally these gauges are run on tubing and in case of gauge failure, a workover rig is required to replace the malfunctioning gauge (there are 6 wells with malfunctioned/failed gauges in the operated field). The WL retrievable option would eliminate the $500,000 rig cost per well to replace malfunctioning or damaged gauges.