bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions Between Uronic Acids and Chromium(III)
Authors: Cettn Zeynep , Kantar Cetin , Alpaslan Musa
Published: March 2009

Laboratory ion-exchange experiments were performed to investigate the complexation behavior of Cr(III) with uronic acids, such as galacturonic, glucuronic, and alginic acid (main constituents of bacterial exopolymeric substances). The experimental data were analyzed with a chemical equilibrium model in FITEQL to determine the reaction stoichiometries and stability constants for the formation of Cr-ligand complexes. Analysis of ion-exchange data with a chemical model indicates that the accurate description of Cr(III) complexation with both glucuronic and galacturonic acids requires postulation of a mixture of 1:1/1:2 complexes between Cr(III) and ligands under the experimental conditions studied (e.g., pH 4), but that the Cr-alginic acid binding can be modeled based on a reaction stoichiometry of 1:1 Cr-alginic acid complexes. Because of the complex nature of alginic acid, a nonelectrostatic, discrete ligand approach was used to determine proton and Cr binding with the functional groups of alginic acid. In this approach, alginic acid was conceptualized as being composed of a suite of two monoprotic acids (HL1 and HL2) with arbitrarily assigned pKa values of two and four, respectively. The results indicate that Cr binding with uronic acids mainly occurs through carboxylic groups under acidic to slightly alkaline pH conditions (e.g., pH < 8). The overall results of the present study indicate that the formation of such Cr-ligand complexes may have a pronounced effect on Cr(III) transport, solubility and bioavailability in natural systems.
Evidences for New Attractive Gas Exploration Targets in Abu Dhabi Upper Permian Section
Authors: Taher Ahmed K. , Al Suwaidi Ahmad S. , Al Habshi AbdulRahman
Published: March 2009

The great Paleozoic system of the Arabian Gulf forms one of the most prolific hydrocarbon producing systems in the world. The Primary elements of this system like source, reservoir, seal and traps are extended throughout the eastern Arabian Peninsula and have exceptional scale and quality. Modeling of the structural growth history, in conjunction with the hydrocarbon generation and migration in the area, has shown that early growth and charge were essential conditions for the formation of economic hydrocarbon accumulations.

The recent basin modeling of the Silurian Hot Shale source rock showed that the gas generation deadline was during the Late Tertiary (20 Ma), while the onshore fields main phase of structural growth was during the Late Cretaceous Semail Ophiolite Obduction. Also, the potentiality of gas accumulations was further enhanced by the Late Tertiary tilting. The tilting resulted in spilling and migration of gas from the palaeo-structures in the east towards the giant structures in central Abu Dhabi.

The Upper Permian Fluid Inclusion Volatile (FIV) analysis proved the presence of strong gas migration through much of the Abu Dhabi area and based on that, no source risk is present as previously suggested for the Upper Permian and Lower Permian reservoirs. The fluid inclusion analysis generally observed more mature source that resulted in drier gas in the onshore area and wetter gas to the northwest in the offshore fields.

The drilling results evaluation indicated the presence of significant hydrocarbon shows while drilling the Upper Permian porous carbonate intervals. Also, the log data indicated the presence of high hydrocarbon saturation that ranges between 50 and 90% in most of the onshore Upper Permian drilled structures. However, the longer diagenesis process and the deeper depth of the burial of onshore structures have greatly affected the reservoir properties and possibly resulted in high non-hydrocarbon content.

The causes of failure of some Upper Permian reservoirs in Abu Dhabi are most probably related to the limited data and experience at that time; which resulted in drilling and testing difficulties that possibly caused formation damage of the Upper Permian reservoirs. Also, the seal preaching and the limited charge could not be ruled out as negative factors for lack of gas accumulations in the Upper Permian section. However, the current technology improvement in basin modeling, deep drilling and tight reservoirs testing may turn the Upper Permian negatively tested reservoirs in Abu Dhabi fields to an attractive exploration targets.
A New Approach For Improving Permeability Estimation by Integrating Sequential Gaussian Simulation (SGS) With Co-Active Neuro Fuzzy Inference System (CANFIS) Network
Authors: Rafiei Yousef , Mirkalaei S. M. Mousavi , Masoudi Rahim , Ataei A. , Khordoo Mahmood
Published: March 2009

This paper shows that geostatistical modeling integrated with Artificial Neural Network (ANN) can be effectively used to estimate permeability when limited amount of core and log data is available.

The goal of this study is to create a good calibrated data set, and then designing a proper network for permeability estimation in one of Iranian oil reservoir. In this reservoir coring have been done only in one well. Therefore due to widely scattered and limited number of data, conventional methods of permeability estimation such as empirical equations and multi linear regressions gave poor prediction.

New approach was developed in which, geostatistical modeling is performed to create comprehensive data set. After that this data set will be used to design and train neural network for prediction of permeability.

In this work, at first the reservoir has been classified in to two different flow units to overcome the extreme heterogeneity of the reservoir. Then Sequential Gaussian Simulation (SGS) was performed to obtain very fine permeability distribution versus depth and log data in cored intervals of each flow unit of the reservoir. After that uncertainty analysis has been done to create data set by selecting the best points with highest probability and lowest value of standard deviation. These data were input to design and train the Co-Active Neuro Fuzzy Inference System (CANFIS) Network. This network is based on Fuzzy Logic algorithm that its parameters obtained from learning rules of neural network. Then core data are used to test the network. The results show the acceptable estimation of permeability. Finally network can affectively be used to estimate permeability in uncored but logged wells.
Applying Precision Drill Pipe Rotation and Oscillation to Slide Drilling Problems
Authors: Gillan Colin , Boone Scott , Kostiuk Greg , Schlembach Catherine , Pinto Jason , LeBlanc Marc
Published: March 2009

The paper describes how a computer controlled top drive can address slide drilling problems and reduce rigfloor personnel exposure using precision pipe rotation and oscillation. It presents the advantages of such a system in solving the problem of setting a downhole toolface orientation and compares itself with the current practice. The paper explains further improvements in drilling efficiency and toolface control in the slide drilling mode in four case studies using field data and log analysis. A case history discusses how an operator was able to use the system to drill complex 3D wells using mud motors where previously only rotary steerable systems were capable. A section presents how the system reduces personnel exposure on the drill floor. The system is compared to other techniques of improving drilling performance in highly deviated directional wells.

In the current drilling environment, operators are constantly seeking to reduce costs, improve drilling efficiency and ensure the safety of all personnel. This application adds efficiency to the drilling process in reducing rig flat time caused while establishing downhole toolface settings for directional control. It also adds efficiency by delivering more effective weight on bit in highly deviated directional wellbores and in providing a digital method of controlling downhole toolface while drilling. The improved toolface setting procedure via a touch-screen computer removes the need for directional personnel to chalk drill pipe and spend time on the rotary table, working instead with the driller from the doghouse or control cabin to achieve the required pipe rotation and toolface. The directional steering control system can also be used to maintain a desired toolface setting across drill pipe connections, dramatically reducing the flat time per connection. In these key elements, this system provides significant time saving advantages over the current practices.
Innovative Solution to Isolate Cross Communicating Reservoirs in Short Radius Wells
Authors: Al-Mumen Adib A. , Balghoneim Hatem F. , Al-Amri Khalifa M. , Al-Baggal Zaki A.
Published: March 2009

Cross communication between reservoirs is a common phenomenon in oil fields worldwide. The cross communication not only hampers production but also alters reservoir properties which affects the future recovery targets. Isolation of these cross communicating reservoirs in short radius application has always posed a serious challenge to drilling engineers worldwide. This paper will describe two challenging remedial workovers where the window was successfully isolated and squeezed after isolating the short radius curve section. The first well is a bare foot completion while the second well was more challenging as it is completed with production equalizer liner. The paper will also highlight the evaluation process and risk assessment of the other options with economic analysis. Moreover it will shed some light on the limitations of the available retrievable isolation plugs in short radius applications. At the end the paper will emphasize the time and cost saved in achieving the objectives and will show production results of the two wells after the remedial work.
Improved Method for Compositional Modeling Using a Fine Scale Geological Description Within Gas Injection Pattern in Carbonate Reservoir
Authors: Obeida Tawfiq , Gibson Adrian , Al-Hashemi Hussain , Baruah Bikram
Published: March 2009

The objective of this paper is to address the challenges that are frequently encountered in simulation studies when using local grid refine (LGR) within upscaled models. The difficulties mainly arise due to the unreliability of populating the fine grids with reservoir properties and attributes.

Dynamic modeling of a pilot is an important task to predict fluid flow and reservoir behavior which is a major step of pilot design. Dynamic models usually have many limitations when it comes to geological description due to the upscaling of fine-grid static model. Using local grid refinement (LGR) alone for the pilot area within a coarse dynamic model also would not enhance reservoir description of the pilot area without a realistic reservoir description. This work was aimed to provide an improved method for the proper simulation of pilot project in order to optimize the design of the pilot injector, borehole location and length. Furthermore, the model would be used to plan an efficient reservoir monitoring program including an optimized well data gathering with sponge coring for defining the remaining oil saturation.

To overcome these limitations, the proposed method introduces a special fine scale LGR covering the pilot area within the upscaled dynamic model. Whereas the upscaled model has 36 layers, the LGR contains exactly the same fine-scale layering scheme and reservoir properties as the static model with 160 layers. Thus, it eliminates the upscaling process within the LGR. This process will ensure a better quality history match, for example the TDTs and RSTs derived saturations when compared against the fine layer LGR from the dynamic model.

The dynamic model in this study is a large sector model (Nx 167, Ny 98 and Nz 36) with a detailed LGR (Nx 130, Ny 145 and Nz 160). The fluid properties were calculated from a 10-components equation of state (EOS). After the addition of the LGR, the model history match was updated. Several prediction cases were then studied to optimize well location (injector and observation wells) in order to convert the existing inverted five-spot gas pattern into water injection line-drive. Several saturation maps and profiles were generated to predict the breakthrough time for each observer and utilized to design the future pilot monitoring program. The new data will be utilized for future updates of the history match and performance of pilot under the optimum scheme of sweep and thus well spacing.
Advanced Technologies for Critical Drilling Applications
Authors: Jellison Michael J. , Spoerker Hermann F.
Published: March 2009

This paper provides a review of recent technology advancements and addresses practical considerations associated with drill pipe and drill stem components for extreme drilling applications. Ultra-high torque double-shoulder rotary connections are often employed in these applications potentially complicating proper design and material selection for cross-overs, top-drive subs, pup joints and other accessories These new connections often employ materials with higher strength requirements than the standard API connections they replace. The paper outlines recommendations for material strength and design parameters for various drill stem accessories. High-performance connectors' impact on BHA design is also addressed. Weight tapered drill string designs with double-shoulder connections can result in mismatched connection bores or ID's. Guidelines to accommodate this mismatch along with supporting finite element modeling results are presented.

Proper hardband selection, application and maintenance are essential to successfully and safely drill world-class UD, ER and deep-water projects. Hardband system trends for critical applications are highlighted, and recent hardband casing wear and tool joint protection test results obtained using an advanced hardband wear machine are discussed.

Due to the dramatic increase in oil prices the industry has seen a re-emergence of deep and ultra-deep drilling projects that encounter H2S gas. The paper provides initial results from a study of the effect on S-grade drill pipe samples to various H2S exposure concentrations, representing typical conditions when circulating a gas kick to surface.

The surge in critical drilling has led to an increasing trend of drill stem friction heating failures. The paper includes characteristic features of these failures along with case histories and prevention methods. High-speed telemetry (wired) drill pipe has been successfully deployed on critical drilling applications in various parts of the world. The paper provides an update on this exciting technology and reviews recent case histories.
Permeability Estimation Using Log Data, Abu Dhabi Offshore Field, UAE
Authors: Bazara Magdi , Salman Salman M.
Published: March 2009

One of the major elements used to evaluate an oilfield reservoir is the rock Permeability. It's also used in many other aspects such as reservoir simulation, rock type definition, etc. There are many methods utilized to measure / predict formation permeability (Well Test, MDT, Core analysis…).

Rock Permeability indicator significantly increases with porosity for the intergranular-type formation (not applicable for noninterganular rock, such as formation containing solution channels, vugs or fracture); however it is also quite dependent on the surface area presented by the grains. On the other hand, irreducible water saturation reflects the surface area. Therefore a function of porosity & irreducible water saturation can help in prediction of the absolute permeability. In our case study, the actual Sw (initial) were used in this function, hence the Permeability obtained actually represent the effective rather than absolute value.

Through the petrophysical evaluation of an offshore oilfield in Abu Dhabi, it was noticed that by applying a function of Water Saturation, Porosity & other coefficients, there were a good match between the Permeability estimated using open-hole log data & Permeability measured from the core sample in the laboratory. A step further of this quality check to this function is taken by comparing these results to the wells test & having an overall comparison over the full field data in-hand.

This paper focuses on establishing a correlation between open-hole log data interpretation & permeability measurement from the core sample that resulted in generating an empirical equation capable of predicting the permeability from the open-hole log data.
An Update and Perspective on Field-Scale Chemical Floods in Daqing Oilfield, China
Authors: Pu Hui , Xu Qinglong
Published: March 2009

Chemical enhance oil recovery(EOR) like polymer flooding and Alkaline-Surfactant-Polymer(ASP) flooding have been applied throughout the world for more than 20 years. However, few large-scale successes with these processes have been reported, except in China. To date, polymer flooding has been successfully applied industrial scale in Daqing since 1996. Polymer flooding alone contributed more than 10 million tons of oil in 2006, which occupied 25% yearly rate of Daqing. Incremental oil recoveries of up to 14% of OOIP have been obtained in the field. Much experience and lessons have been learnt on large scale polymer flooding including: major factors that influence the recovery and methods to increase the recovery; measures to obtain a uniform polymer injection profile; and how to lower the costs of polymer flooding.

Also Daqing performed researches on other chemical floods application, such as surfactant flood, micellar-polymer flooding(MP), alkaline flooding, alkaline-surfactant-polymer flooding(ASP), alkaline polymer flooding(AP), ASP-foam, especially ASP. Those chemical floods were field tested or are testing to increase oil recovery, to study the feasibility, to provide technical and practical experience for expanding, and to find suitable post-polymer flooding enhanced oil recovery EOR technology. Through tests, the injectivity and productivity of ASP systems, the best technique of artificial lift and stimulation measures for low efficiency wells, chromatographic separation analysis in condition of different well spacing, and economic analysis of chemical EOR were all studied. Pilot test results showed that over 20% OOIP recovery can be obtained over that of waterflooding, and is both technically and economically feasible.

Overall, experiences and lessons learned in field applications of chemical floods in Daqing are extremely valuable not only for expanding chemical EOR to other areas of Daqing, also for other countries.
Mechanical Earth Model (MEM): An Effective Tool for Borehole Stability Analysis and Managed Pressure Drilling (Case Study)
Authors: Afsari M. , Ghafoori M. R. , Roostaeian M. , Haghshenas A. , Ataei A. , Masoudi R.
Published: March 2009

As a borehole is drilled, hydraulic pressure of the drilling mud must replace the support lost by removal of the original column of rock. But mud pressure being uniform in all directions cannot exactly balance the earth stress. Consequently, rock surrounding the borehole is distorted or strained, and may fail if the redistributed stresses exceed rock strength. The bottom line for the drilling engineer striving to maintain stable hole is choosing the right mud weight.

The aim of this study is to build a Mechanical Earth Model using available data for one of the Iranian oil field to evaluate wellbore stability and to choose optimum mud weight.

For making MEM different sources of data including, drilling data, logging data, DST, MDT, LOT, FIT, etc were used. After making MEM with available data, suggestion for selection the right mud weight for each interval to prevent the common instability problems (lost circulation, borehole breakout) was made.

MEM for this field can now be used to predict not only the safe mud weight window and possible drilling hazards, but can also be used for studies like sand production and perforation stability and so on.

Numerical modeling has been carried out using MEM data for comparing analytical and numerical wellbore stability analysis to select optimum mud weight, to investigate the feasibility of managed pressure drilling for problematic formations, and to determine the most effective azimuth for drilling horizontal wells into the reservoir section.
Understanding of Oilfield Souring and Effective Monitoring: Two Cases Study
Authors: Nengkoda Ardian , Mandhari Musallam , Hajri Mohammed , Barhi Hilal , Qasmi Liali , Hofland Ron
Published: March 2009

In the X oilfield Sultanate of Oman, water has been injected since June 2001 for EOR purposes. The water supply sources, was used through 4 dedicated injection wells, at a maximum total rate of 4000 m3/d in early 2003. By end of April 2003 the injection water source was switched to produce water, and separated at in line separator. The production wells suddenly turned to produced high H2S, while the well injectivity decline around 50% and levels have caused concern for on going Field Development scenarios. Meanwhile, in opposite, in Y oilfield, when discovered, the field was found to be sour, hence production facilities were designed for sour service. Occasional monitoring confirmed high H2S levels to prevail, but also showed an alarming increase with time, casting doubts on future integrity assurance. As the materials used in the X and down stream receiving facilities are not to be NACE 175 souring compliant and consider H2S released are hazard for safety. Starting December 2005, production chemistry and reservoir study have initiated an integrated H2S Monitoring and implemented a Mitigation Program by improving H2S onsite measurement and method revision, adopted instrument calibration accuracy, established frequent surveillance teams, investigated the caused of souring by Sulphur Isotope methodology for both X and Y field, and monitor the produce solid. Overall its improved business performance, HSE awareness, saving the plant upgrade cost, and finally now days in November 2008, the H2S level from X Field become traces and the area is safe for full field development.
Sulfur and Asphaltene Deposition During CO2 Flooding of Carbonate Reservoirs
Authors: Zekri Abdulrazag Y. , Shedid Shedid A. , Almehaideb Reyadh A.
Published: March 2009

Simultaneous sulfur and asphaltene deposition in porous media as a result of CO2 injection may significantly reduce the CO2 flooding injectivity and create plugging problem and might affect the recovery efficiency of the process. Accurate assessment of sulfur and asphaltene deposition during CO2 is critical information for the design of viable CO2 flooding process.

The main objective of this work is to investigate the simultaneous deposition of sulfur and asphaltene in the porous media during CO2 flooding. To achieve this objective, the influences of water saturation, type of flooding process i.e. slug and continuous, CO2 injection rate, and permeability of the system on the oil recovery and the losses of sulfur and asphaltene in the reservoir rocks were investigated. Nine experiments were carried-out using one of UAE oil reservoirs crude oil. The results indicated that both sulfur and asphaltene were precipitated in the system and in general higher sulfur loses to the pores media as compared to asphaltene was observed.
The Use of Tracers for Reservoir Characterization
Authors: Anisimov L. A. , Kilyakov V. N. , Vorontsova I. V.
Published: March 2009

The use of tracers in the reservoir studies shows that this is the best method to evaluate the downhole region of the well and interwell space. Traditionally, the reservoir studies have combined the integration of the geological, geophysical, and well tests as well as geochemical data and production history to construct geologically realistic models. Tracer methods give new opportunities to evaluate the fluid-flow properties and continuation or compartmentalization of reservoirs. Radioactive and chemical tracers have been used in Volgograd Region to construct hydrodynamic models of clastic and carbonate reservoirs.

The method of radon indication has been used for downhole region evaluation. After radon injection, the permeability along the vertical section in a well can be calculated according to the level of radioactivity on a log. The convective nature of tracer-tests provide additional information about the reservoir. The following parameters are used for interwell space evaluation: tracer velocity (time of flight from injection to production wells) in a reservoir; tracer concentration as the consequences of tracer dissolution in formation fluid flow; frequency of the tracer presence in samples – a number of tracer pathways from injection to production wells. The use of tracer survey method can evaluate the vertical fluid flow barriers, reservoir continuity in every block, fluid-flow properties, and understanding of the reservoir architecture in the interwell space. The main result of tracer method is the ability to detect the ultra high permeability zones that cannot be found by other methods of reservoir analysis.
Integrated Fracture Study using Formation Micro Imager, Stoneley Waves and Formation Evaluation Results in Carbonate Reservoir at Gulf of Suez, Egypt
Authors: Bassim Essam A. E. A. , Yamaguchi Kaoru , Juandi Dedi , Emam Mahmoud , Ali Aziza
Published: March 2009

The carbonate reservoirs in Gulf of Suez area have complex geological structure due to the existence of fractures associated with faults. Thus, fracture characterization of this complicated area is very important to understand the reservoir behavior and hence assigning the best completion intervals for the producing wells.

In this paper, we developed a workflow of integrating formation micro imager, Stoneley waves and petrophysical analysis for better fracture characterization and selecting the best perforation intervals for a producing well. This workflow is applied on well NWO-1, in the Northwest October Concession in the Gulf of Suez area over the carbonate reservoir.

The well was drilled on the peak of anticlinal feature created by fault propagation fold of a normal fault that located nearby the well. The main objective was to determine the structural geology features (i.e. fractures), its orientation and the diagenetic features (i.e. vugs) using formation micro imaging tool. Also, to quantify the effectiveness of fractures as fluid conduit mainly in the carbonate reservoirs either in Thebes or Mokattam Formation via Stoneley waves derived from processing result of sonic measurement. This is combined with the petrophysical interpretation using the elemental spectral device data and other conventional open hole logs to provide a comprehensive petrophysical formation evaluation.

The study reveals that the highest average fracture density is over (Layer-A & B) at the upper most interval of Thebes Formation around 2.2 fractures/ft and (Layer-C) at the bottom around 1.77 fractures/ft. These fractures were proved to be of good fluid conduit based on both Stoneley waves and the petrophysical interpretation. The two layers A and B were recommended to be tested and the DST (Drill Steam Test) results proved the higher productivity than layer C which confirms the outcome from our integrated study.
Awareness and Expectation—Gender in the Workplace
Authors: Lau Richard , Lau Laura , Al Hasani Nadia
Published: March 2009

One of the most important legacies of the late President, Sheikh Zayed Al Nahyan left to the people of the UAE was his insistence that women participate fully and equally in the growth and prosperity of the UAE. This paper examines the readiness of students, professors and professionals to accept women in professional roles in the oil and gas industries in the UAE.

Working at the Petroleum Institute in Abu Dhabi, the researchers train both men and women to become future engineers for the Abu Dhabi National Oil Company (ADNOC). In this study, future and present professionals were asked to rate their opinions about working with women in integrated work places. To solicit these opinions, a survey of seven questions, with a place for comments, was distributed to various age groups in various job categories. Distributed in educational institutions and local petroleum societies, the survey asked participants to rate their willingness to hire, mentor, work with, promote, and work for a woman engineer.

This paper analyzed a seven-statement survey. Finding that although most respondents agreed that greater numbers of women would be welcomed into the workplace, the researchers noted a stubborn minority of both men and women who did so with reservations. Looking for a plausible explanation, they concluded that stereotyping might be a motivator.described ways that included mentoring, presenting women role models, demanding academic parity, engaging in professional activities, etc. to combat stereotyping to ensure a smooth transition of more women into the work place.examined roadblocks, like [1) low number of women, 2) retaining and promoting women employees and 3) understanding differences] that companies needed to be alert to for a successful diversified culture and then listed five strategies [1) women-to-women mentoring 2) empathy vs. advice 3) anger management 4) working through problems 5) healthy environment] that must be addressed if companies want to hire and, more importantly, retain women.concluded that while programs to address the needs and attitudes of future women engineers are in place or being established, programs for future men engineers are not. This might be the first place that women and men should look for parity.
Minimizing Risks, Maximizing On-Bottom Drilling Time: Turbodrilling with Impregnated Bits Improves Efficiency and Circumvents Trouble Time, Southern Oklahoma
Authors: Langille Peter , Deen Aron , Klassen Jay
Published: March 2009

Drilling in the Anadarko Basin in southern Oklahoma can present a number of distinctive challenges including fractured formations, conglomerates and other eccentric geologic phenomena. In this unpredictable drilling environment, it is difficult to optimize/refine the bit/tool and BHA selections, resulting in unacceptable or inconsistent drilling performance.

To maximize on-bottom time and cut costs, operator and service-company engineers conducted an in-depth analysis in an attempt to improve section economics. They selected a consistently troublesome application where inconsistencies in the use, performance and dull conditions of bits in close offsets were driving up field development costs. From this group, a specific interval was selected for analysis and the data compared with direct offset runs. In the study, engineers considered bit design/materials, turbodrill and BHA stabilization and drilling parameter optimization. Finally, turbodrill/impreg limitations were considered.

The analysis determined that turbodrilling with impregnated bits was a viable option to create savings and could effectively optimize drilling in applications where:

specific lithology/formation tops are difficult to define/predict deviation is caused by hard formations encountered at severe dip angles high probability of bit/tool damage from impact/abrasion excessive fishing/tripping issues hole stability/quality may be compromised by frequent trips roller-cone and fixed cutter bit performance is inconsistent

The new-style turbine/impreg BHA was run with outstanding results. The test interval was successfully drilled, eliminating multiple bit trips and reducing overall days. Cost savings were substantial versus a direct offset well that experienced 38 days of trouble time through the same formations. This trial run gives considerable strength to the hypothesis that impreg/turbine drilling can significantly reduce risk compared to traditional BHAs used in direct offsets. The operator plans to further explore the turbodrill/impreg BHA in the near future.
A Composite Seepage Model for Fractured Reservoir
Authors: Jinde Feng , Ruilan Luo , Linsong Cheng , Yuwen Chang , Lijun Yu
Published: March 2009

For fractured low-permeability sandstone reservoir, it is very difficult to use the conventional method to handle the stochastically distributed natural fractures, which do not connected with the wells, in the theoretical study of the naturally fractured reservoir. To study the seepage law of the fractured reservoir, a fractured heterogeneity composite reservoir seepage flow model is proposed by using the equivalent flowing resistance method. With this model, the effects of natural fracture parameters on productivity and formation pressure were investigated. The results indicate that the fractures within 10m to the wellbore will have great impacts on pressure distribution and productivity; and the impacts of fracture length, fracture aperture and fracture number on pressure distribution and productivity will decrease after they are greater than some certain value. The study clarified theoretically the reason that fractures improve the productivity.
Execution Success in a Platform Drilling Campaign
Authors: Burmaster Kolby , Chando Jesse M. , Vaczi Kenneth
Published: March 2009

This paper presents the results of a five-well extended reach drilling (ERD) sidetrack program in offshore California. The challenges of drilling the ERD sidetracks were compounded by potential drilling hazards, the limited capability of rig equipment, and extensive activities required to restart a cold stacked platform rig. Despite these challenges, the program was delivered 138 days ahead of schedule and 44% under budget.

This case history describes the key elements of the project that contributed to execution success, including:Early identification of technical challenges and solutionsPlanning processes that ensure alignment across functionsAn active goods and services quality initiative to maximize equipment reliabilityIncorporation of key learnings from other teams around the worldContinual redesign from well to well based on lessons learned during the execution phaseTechnical solutions that balance potential risk and reward

Specific cold start and ERD sidetrack practices are discussed, as well as the work processes that were effective in establishing a mindset of continuous improvement and flawless execution.

Introduction

Due to the significant cost of drilling, it is critical to apply a rigorous and disciplined approach to planning and execution. Maintaining a mindset of flawless execution facilitates improved performance by identifying optimization opportunities while balancing potential risk exposure (Newman 2005). The success of the operator's platform drilling campaign can be attributed to having the right team of people in place using proven planning and execution processes. These processes drove an understanding of the technical challenges and potential solutions early in the project, and ultimately delivered a five-well ERD sidetrack program ahead of schedule and under budget.

Field Overview

The Santa Ynez Unit (SYU) is located approximately 20 miles west of Santa Barbara, California. Operations in SYU comprise an oil and gas processing plant at Las Flores Canyon and three offshore platforms located in federal waters in the Santa Barbara Channel, as illustrated in Fig. 1. The three production platforms (Hondo, Harmony, and Heritage) range from 5 to 9 miles offshore and lie in water depths of 850, 1,200, and 1,075 ft, respectively. Each platform has a company-owned drilling package installed. All electricity for the drilling and production equipment is generated onshore and transmitted offshore through subsea power cables. The oil and gas produced offshore is transported through subsea pipelines to the Las Flores Canyon processing plant. These fields produce primarily low-gravity 12- to 20º-API sour crude from the highly fractured Monterey chert formation (Walker 2008).
Achieving Improved Performance Through Drilling Optimization and Vibration Management at a GoM Development Project
Authors: Plutt L. A. Jacobsen , Pere A. L. , Pardo N. O. , Rodiguez E. M.
Published: March 2009

The presented Gulf of Mexico (GoM) field presents drilling and evaluation challenges common to sub-salt deepwater plays. These include directional control, drilling efficiency, wellbore integrity and vibration management. Expandable reamers are used to drill challenging thin-bedded alternating sands and shales. This drilling configuration can result in high levels of vibration that can be detrimental to measurement while drilling and logging while drilling (MWD/LWD) tools. Worldwide estimated costs for vibration-related failures are in the order of $300 million per year.

A multidisciplinary team worked to deliver continuous improvement in drilling performance and risk management for the presented field during the last two years. This continuous improvement cycle has been based on comprehensive pre-well planning, downhole data acquisition with real-time diagnostics and thorough post-well analysis. This systematic approach provided the team with an accelerated learning curve from each well by enabling quick, informed decisions and learning from data, rather than failure patterns.

Although this cycle has been used throughout each well, it has proven particularly critical in the intermediate interval, which combined directional work and reaming while drilling using expandable reamers. In offset wells, before this drilling optimization approach was introduced, no well in this interval had been successfully drilled in one run.

State-of-the-art technology to monitor downhole environment in real time was introduced and enabled field personnel to react immediately to damaging vibrations by adjusting drilling parameters and applying best practices for improved borehole quality and drilling performance. As a result, this section was drilled in one run in the seven consecutive wells drilled, and all formation evaluation data acquisition and directional objectives were met with low hole tortuosity, facilitating casing placement.

This paper provides an overview of the challenges, drilling optimization process, lessons learned and best practices derived from advanced bottomhole assembly (BHA) modeling, and real-time vibration mitigation management.
Experimental Study of MSE of a Single PDC Cutter Under Simulated Pressurized Conditions
Authors: Rafatian Navid , Miska Stefan , Ledgerwood III L. W. , Ahmed Ramadan , Yu Mengjiao , Takach Nicholas
Published: March 2009

The downhole pressure environment is one of the most important factors affecting the rate of penetration. It is believed that impermeable rocks experience high differential pressures due to shear dilatancy and become stronger and thus more difficult to drill. However, recently performed atmospheric and pressurized single-cutter experiments show that contrary to this belief, even at low pressures (100–200 psig) and even with permeable rocks, significant increase in Mechanical Specific Energy (MSE) is observed compared to atmospheric tests.

The experiments were carried out in a single-cutter high-pressure testing facility refurbished with high-precision sensors and data acquisition system. In the experiments, a 13-mm PDC cutter was used to cut Carthage marble and Indiana limestone samples with depths of cut ranging from 0.025 to 0.050 in. More than 70 high precision tests were performed on these two rock types under confining pressures ranging from 0 to 1000 psig. The confining fluids were either water or mineral oil.

Unexpectedly, analysis of the MSE consistently showed that increases in the confining pressure as small as 150 psig can increase the MSE of the cutting process significantly and reduce the cutting efficiency by half. These reductions in the cutting efficiency that were even more dramatic in the permeable and saturated Indiana limestone could not be explained by the strengthening of the rock under confining pressures.

Upon analysis of the results of experiments (cutting forces, volume of cuts, visual inspections of cuttings, etc), a new theory is proposed to explain this unexpected behavior. This new theory, based on the frictional forces and the cutting mechanism under pressure, gives useful insights into the physics of cutter-rock interaction. Such insights are invaluable to the improvements of drilling practices selection (WOB, type of drilling fluid and its properties, etc) and the rates of penetration.
Real Time Production Monitoring Uncovers Potential for Recovery Optimization, Field Case Study, Western Desert, Egypt
Authors: Hanafy K. M. , Elsherif T. A.
Published: March 2009

With the dramatic increase in oil prices, oil operators are not only concerned about oil production, but also, they are aiming at the optimum oil production. Optimization of an oil producer is not easy as it might seem to be.

Moreover, oil price increase promoted for technology improvement, and set the unconventional techniques of the past to be conventional nowadays. This boom in technology application permitted high margin of investments to optimize wells/fields production, and gave production/reservoir engineers a good hand in obtaining better data for decision making.

The most important part of well/field production optimization is identifying candidates, and to recognize potentials we need to have efficient reservoir/production data. Because the whole process starts with formation inflow performance which determines how far we can go with this formation without having production problems such as; water conning, erosion induced by solid production, etc.

In this paper we are illustrating the various steps that we have taken to optimize a well producing from naturally fractured carbonate reservoir with active water drive, using a combination of modern technologies in combination with real time production monitoring systems, we were able to double this well production without entraining any problems, in addition capturing pressure transient data which enabled us to manipulate these success story with the rest of the wells in that field.
Roller Reamers Improve Drilling Performance in Wells Limited by Bit and Bottomhole Assembly Vibrations
Authors: Sowers Steven F. , Dupriest Fred E. , Bailey Jeffrey R. , Wang Lei
Published: March 2009

Stick-slip and whirl are vibrational problems that commonly limit drilling performance in hard formations and extended reach wells. The introduction of roller reamers has resulted in significant performance improvement in a number of the operator's drill teams with chronic stick-slip or whirl-induced borehole features.

Whirl is a dysfunction characterized by lateral vibration that may occur both at the bit and in the bottomhole assembly (BHA). When whirl becomes severe, lateral vibrations cause significant side forces in stabilizers. Frictional drag resulting from these side forces causes high levels of torque to be generated at stabilizers and can result in stick-slip (a condition characterized by fluctuations in the rotational speed of the BHA). The operator refers to this as "coupled stick-slip" because the condition is caused by whirl in stabilizers. When these conditions exist, the replacement of stabilizers with roller reamers significantly reduces the potential for torque-generation at the contact points. Consequently, more torque becomes available to the bit and the driller may raise weight on bit (WOB). This results in reduced levels of bit whirl and improved rate of penetration (ROP). The reduction of bit whirl and elimination of stick-slip prevent damage to bit and BHA components.

Roller reamers are also seen to serve the historical purpose of conditioning the borehole. The operator's field experience indicates that the need for conditioning is often due to whirl-induced features in the borehole. These features include spiraling and ledges. The use of roller reamers greatly reduces the prevalence and impact of whirl features.

This paper details the conditions where roller reamers provide benefits allowing improved performance. A conceptual model for coupled stick-slip is provided as well as a summary of whirl-induced borehole features which may be mitigated with roller reamers. Representative examples are provided that show drilling performance improvements using roller reamers to mitigate these conditions.
Improvements in Completing and Testing Multi-Zone Open-hole Carbonate Formations
Authors: Brooks Robert T. , Scott Philip , Scott Steven
Published: March 2009

This paper presents a methodology for executing multi-zone well tests in an un-cemented open-hole completion. Hydraulic isolation between zones is achieved using casing annulus packers rather than cement. Sliding sleeve port collars provide a means of selective interval testing, when used with polished bore receptacles and seal stacks to allow well control and test string spacing.

The techniques described here eliminate cementing and perforating across reservoir intervals; therefore it is an improved method of testing multiple zones in fractured and low permeability carbonate reservoirs. Multiple zones can be individually tested and retested, in any order, on a single trip in the hole with drill stem test tools, representing a significant step change in well testing methodology.

Performing well tests on single zone wells can be done in open-hole or cased hole. Open-hole well tests are usually preferred because they exhibit lower skin damage and improved productivity, especially in low permeability, fractured carbonate reservoirs. For multiple zone testing, cementing and selectively perforating are more common.

A well test performed in an exploratory well in Qatar used the basis of this approach. Subsequent to this, well tests in China and Oklahoma, (USA), used this approach successfully. One common well test objective was to establish sufficient flow allowing the chosen reservoir to be evaluated, without the need to stimulate. Although stimulation was not entirely eliminated in this test case, a reduction in test time was achieved. The reduced number of trips in the hole also reduced HSE exposure. This last improvement was particularly important in one well as the well flow stream contained H2S. Although some operational difficulties were encountered and overcome, the system was proven technically viable, and has the potential for significantly reducing completion and testing time for a multi-zone well, as well as mitigating HSE hazards.
New Alternative to Selectively Fracture Stimulate Extended-Reach, Horizontal Wells
Authors: Surjaatmadja Jim B. , Sierra Leopoldo
Published: March 2009

The requirements of oil and gas producers to maximize hydrocarbon recovery in low-permeability environments have often been satisfied by drilling longer cased or openhole horizontal sections, or by maximizing reservoir contact by perforating multiple laterals or branches to the main bore. As production declines, these complex well completions have brought many challenges to well interventions and stimulations.

The number of such complex wells and the number of selective packerless fracture stimulations in long horizontal sections has increased significantly in the last few years, especially in Saudi Arabia in oil/gas producing wells, and eventually, for improving injectivity of water-injector wells. The selective and packerless fracture stimulation technology in wells completed with long, horizontal openholes or cased holes has not been possible until now, especially when coiled tubing is used. This is because the coiled tubing, when equipped with the selective fracturing tool, will not be able to reach the entire horizontal section without the use of mechanical tractors or agitators and because of the incompatibility of the tool assembly and tractor/agitator systems.

This paper presents, for the first time, the new tool designed to make tractor/agitator systems compatible with the selective fracturing tool. It presents a detailed job design and considerations used to perform the first field application of the tool in Saudi Arabia.