bluuebunny/crossref_metadata_2025_split huggingface dataset:
Waterflood Pilot in a Mature Fractured Carbonate Reservoir
Authors: van Schijndel L. A. E. , Swinkels W. J. A. M. 
Published: December 2007

Abstract
This study focuses on a giant fractured carbonate field in the Middle East where large undeveloped oil volumes reside in a reservoir that is currently producing via Gas-Oil-Gravity-Drainage. An inverted five spot pilot is planned to address the viability of waterflooding this reservoir, to increase production rates and ultimate recovery.
Three issues determine the success of waterflooding this reservoir. Firstly, there is a sharp contrast between the relatively homogeneous and unfractured low-permeable bottom part of the reservoir, which is the main target for water flooding, and the heterogeneous, highly fractured upper part. Secondly, the ongoing GOGD development and the associated gas injection have resulted in considerable uncertainty in the current oil and gas saturation distribution in the fractures and the matrix. Finally, the uncertainty on vertical to horizontal permeability has a major impact on the waterflood recovery in the bottom part of the layer.
Reservoir simulation of a pattern element shows scope for an additional 20 % recovery in unfractured reservoir units. This is limited mostly by the reduction in sweep efficiency due to water shortcutting through the high permeable layer. Another key uncertainty is free gas production caused by the ongoing GOGD development.
The results of the element model simulating a field wide pattern were compared with the results of a second unconfined reservoir model representing the pilot five spot.
The unconfined pilot will show lower production rates than the full pattern development due to insufficient pressure support. Not appreciating this phenomenon can cause underestimation of expected pattern water drive performance.
On the other hand pattern drive performance can be overestimated on the basis of the pilot, since gas will migrate out of the unconfined pilot area and oil mobility in the pilot is less affected by the presence of free gas in the pilot.
The pilot five spot is currently being drilled and its results will be used to predict performance of the full field pattern waterflood scheme.
Numerical Simulation to Design and Analyze Pressure Transient Tests in a Shaly, Interbedded Reservoir
Authors: Sinha S. P. , Al-Qattan R. 
Published: December 2007

ABSTRACT
Analytical methods of pressure transient analysis are based on idealized well and reservoir configurations. As such, they have a limited scope in describing the reality. In practice, there is a need to interpret pressure transient tests with complex well completions, reservoir shapes, layering and complex reservoir structures. This is facilitated by the high precision modern pressure gauges, which can reveal details. Numerical simulation becomes a necessity in such complex cases as shaly interbedded reservoirs of Greater Burgan Field with moderate to high heterogeneity.
In the present work, two cases of pressure transient tests in an interbedded reservoir have been discussed. The first case is that of multiple perforations in multiple permeability zones having variable cross-flow. The second case is also that of well completed in an interbedded reservoir but with the presence of a fault and nearby oil-water contact (OWC). The analysis has been attempted using analytical methods, numerical simulation with PEBI grid and radial model. The results have been analyzed to discover the superiority of numerical simulation with PEBI grid over other methods of analysis.
The main results and conclusions of this paper are as follows: The analytical methods provide initial model review and should remain an integral part of the workflow for doing numerical simulation with speed.The PEBI grid based numerical simulation of pressure transient test provides the best answer in wells completed in an interbedded reservoir with heterogeneity. This may be due to the accurate computation of inter-block transmissibility for heterogeneous formations.The automatic meshing and fast solver for finite element simulation provides speedy simulated responses even in a complex case.An appropriate test design of pressure transient test is achieved using the numerical simulation. The test duration and rate scheduling should be pre-determined to achieve the test objective.
Gas Hydrate Production Technology for Natural Gas Storage and Transportation and CO2 Sequestration
Authors: Masoudi R. , Tohidi B. 
Published: December 2007

Proposal
Gas hydrates (or clathrates) are group ice-like crystalline compounds, which form through a combination of water and suitably sized ‘guest’ molecules under low temperature and elevated pressure conditions. Within the clathrate lattice, water molecules form a network of hydrogen-bonded cage-like structures, enclosing the guest molecules, which generally comprise of low-molecular diameter gases (e.g., methane, ethane, propane, carbon dioxide (CO2), etc).
Although hydrate formation can pose serious flow assurance problems in oil and gas industry, gas hydrates have great potential for positive applications – turning a long standing problem into a potential benefit. Two important properties of hydrates are their very high gas to solid ratio, 1m3 of hydrate may contain up to 175m3 of gas (at standard conditions), and self preservation effects which make them feasible to be transported at atmospheric pressure. They thus present a novel means for gas storage, transportation and delivery, with consequent potential applications in a wide variety of areas, including exploitation of remote gas fields, CO2 sequestration, etc. However, a major barrier to the development of hydrate technology is the current lack of an economical means for the mass-production of solid hydrate in a manageable form.
In this communication, a literature review with a critical evaluation has been conducted on the various reported hydrate production techniques to better understand the production process and identify any shortcomings of such techniques. In addition a new technique is proposed to produce hydrate in which dry hydrate is formed in especially designed reactor in the presence of excess gas. The technique has been applied to production of NG hydrate for NG storage and transportation purposes and CO2 hydrate for application in CO2 sequestration. The preliminarily promising results of series of tests carried out on a NG and CO2 hydrate formation are presented along with an evaluation of atmospheric hydrate self-preservation and dissociation rate versus time and temperature.
A Novel Technique to Acidize Multilateral Open Hole ER Horizontal Wells Drilled in Carbonate Formations
Authors: Nasr-El-Din H. A. , Al-Habib N. S. , Al-Khamis M. , Jemmali M. 
Published: December 2007

Abstract
A new development strategy used by Saudi Aramco for carbonate reservoirs is to drill multilateral, extended reach, horizontal and fishbone wells. This strategy has a significant impact on reducing the development cost per bbl of oil produced, by drilling less wells and requiring less offshore platforms. This is also applied for the development of carbonate reservoirs in highly populated areas.
Drilling multilateral wells is intended to maximize reservoir drainage and minimize water production due to water coning. However, inherent problems with these wells are poor accessibility and uneven acid distribution during matrix acidizing, especially in reservoirs with high permeability streaks. This paper discusses an innovative approach to treat multilateral wells. This technique comprises mechanical diversion in the wellbore and chemical diversion in the formation.
In the past, reentry access to sidetracks from an open hole main wellbore was not possible. This prevented remedial operations on individual laterals and precluded effective reservoir management. To selectively enter and stimulate the desired lateral, a coiled tubing conveyed orienting tool was used. This ensured better acid distribution over the wellbore. To enhance acid diversion in the formation, a viscoelastic surfactant-based acid system was employed.
Well "A" is an offshore dual open hole multilateral horizontal well with a motherbore length of 2,256 ft and a lateral section of 3,558 ft. The lateral was rotary jetted with acidic brine during the completion phase, but the well did not sustain flow after a nitrogen gas lift.
A special CT conveyed multilateral tool was successfully used to enter the lateral. A viscoelastic surfactant-based acid was utilized to remove formation damage induced by drilling fluids, and to enhance the permeability of the formation in the critical wellbore area.
The well responded to the acid treatment and its production exceeded expectations. Challenges, design criteria, field treatment and evaluation, lessons learned, and recommendations are discussed in this paper.
New Methodology to Effectively Stimulate Water Disposal Wells Drilled in Acid Sensitive Sandstone formations in Saudi Arabia
Authors: Nasr-El-Din H. A. , Al-Habib N. S. , Zoraia G. H. , Nasser A. H. , Sunbul A. , Jemmali M. 
Published: December 2007

Abstract
Acid treatments for sandstones differ significantly from those for carbonate rocks. Unlike carbonate acidizing where HCl reacts with carbonates to generate reaction products soluble in water, sandstone acidizing using mud acids produces reaction products that may precipitate and reduce rock permeability. The challenges of sandstone acidizing are to optimize damage removal while minimizing formation-damaging precipitates.
Understanding formation mineralogy and the nature of damage is critical for designing a proper acid treatment. Sandstone acidizing has been always a challenging task, especially if the formation is acid-sensitive. Traditionally, sandstone reservoirs in the Northern Area of Saudi Arabia are not stimulated due to their negative reaction to acidizing.
Wells A and B were drilled and completed as vertical cased hole wastewater disposal wells for a refinery in the northern area of Saudi Arabia. They have been used to dispose the refinery wastewater since 1998. The injectivity of Well A was maintained since it was placed on injection, whereas well B showed low injectivity with a skin damage of + 20.
The major minerals found in the sandstone reservoir are quarts, dolomite, and calcite with kaolite and smectite. The latest analysis of the refinery injection wastewater showed that the wastewater contained suspended solids (iron sulfide) and oil. After several negative clean-up trials by flowing the well back in order to restore injectivity and maintain adequate wastewater disposal capacity of the refinery, it was decided to stimulate or sidetrack the well.
A new design methodology with extensive lab testing was applied to design a tailored treatment to address these challenges. It included a pre-flush of aromatic solvents, then stages of 10 wt% HCl, 9:1 HCl:HF acids. To achieve better acid diversion for the long perforated intervals (200 ft) with high permeability contrast, foamed diverter stages (quality 70%) were incorporated in the treatment.
A carefully designed train of treatment fluids was applied to remove formation damage induced by drilling and injection fluids. Injectivity tests before and after each step of the treatment was recorded and evaluated. Proper design and execution of the stimulation treatment almost doubled the well injectivity index from 47 to 86 b/d/psi. The maximum injection rate increased from 50 to 92 BPM, at 1,500 psi injection pressure. Challenges, fluid selection, design criteria, field treatment, lessons learned, and results of the acid treatments will be discussed in this paper.
Formation Evaluation and Remaining Oil Saturation Estimation with Pulse Neutron Logging Inside Tubing
Authors: Nacache R. , Saad I. , Guru U. , El Mahdy R. 
Published: December 2007

Abstract
Through-tubing carbon-oxygen (C/O) logging is a popular means for reservoir monitoring since a slim logging-inside-casing tool was introduced. The tools are available in 2.5 inch and 1.6875 inch outer diameters. Both the tools log inside of casing to quantitatively determine fluid saturation within the formation. In the absence of any other external information, the C/O technique has limitations when the survey is carried out inside the tubing. However, at times this becomes necessary when the reservoir to be evaluated is covered with both tubing and casing.
There has been limited use of the slim logging-inside-casing tool for completions with both tubing and casing. This application has augmented the C/O methods of saturation estimation for measurements made inside the tubing.
The present work documents the results of a pulse neutron logging operation carried out for estimation of the remaining oil saturation of a reservoir covered with tubing and casing. Both the inelastic capture and the sigma survey were recorded in this well. Careful planning was carried out for achieving an oil saturation precision of around 7 saturation units. The interpretation of the lithology from both the open and the cased hole logs is discussed. A new method was used for estimating the permeability from the cased hole spectroscopy logs. The saturation profile estimated from the C/O log is integrated with the estimated permeability results.
The saturation results are in agreement with field observations and also demonstrate that bypassed reserves can be estimated on the basis of pulse neutron logging carried out inside tubing.
Tuning EOS Using Molecular Thermodynamics to Construct Asphaltene Deposition Envelope (ADE)
Authors: Fahim M. A. , Andersen S. I. 
Published: December 2007

Abstract
The objective of this work to calculate ADE of asphaltene from molecular thermodynamics. Aphaltenes and resins are represented by pseudo-pure components, and all other components in a crude oil are presented by a continuous medium that affects attractions among asphaltene and resin molecules. Model parameters are evaluated systematically from average properties of asphaltenes and resins in crude oils, and from dispersion-force properties of the oil medium. Given the composition of the medium, and asphaltene and resin concentrations, the molecular-thermodynamic, calculated results for the effects of oil composition and pressure on asphaltene precipitation are in good agreement with experimental measurements for differentreservoir fluids, for several crude oils.The absolute average error was 9.8%
Novel Completion Technology Eliminates Formation Damage and Reduces Rig Time in Sand Control Applications
Authors: Garfield G. , Van Sickle E. 
Published: December 2007

Abstract
Formation damage caused by the perforating process is often found to be one of the leading contributors to poor productivity. Fractured and compacted zones, perforation gun debris, and broken formation blockages are common types of damage that can occur inside the perforation tunnel.
Reducing or eliminating initial perforation damage can result in a more productive well over its lifetime. This paper examines a completely new technology for completing wells in unconsolidated formations that eliminates explosive perforation discharges and its associated formation damage risk.
The new technology also provides a means for effective sand control while eliminating the need for conventional sand control processes. The tool system uses telescoping tubes that extend from the liner to the formation by hydraulic pressure and mechanical force. Once the tubes are extended (or telescoped), the liner is cemented in place. The tubes form a conduit from the formation to the casing ID and contain sand-control media which eliminate or restrict the flow of formation sand. This new completion method eliminates gravel packing and minimizes intervention in completion operations, saving substantial rig time. The system does not require large fluid-pumping treatments with high horsepower requirements, which simplifies operational logistics especially in remote or offshore environments.
Formation damage can also be caused by drilling mud and fluid-loss control measures after completion. This new perforating method eliminates both of these highly damaging mechanisms because the tubes extend out past the damage and into the formation, even in a washed out hole.
Application of the new technology will significantly reduce the cost of well construction by eliminating the need for perforating by allowing the production liner and primary cementing equipment to be run in a single trip with an effective means of sand control.
This paper describes initial field test results of the new system, cost comparisons with existing methods, and expected economic benefits over the lifetime of wells in typical applications of this new technology.
Economic Development of "Three Low" Oil Reserves
Authors: Chang Y. , Xu Q. , Tang W. 
Published: December 2007

Abstract
The effective development and utilization of the "Three Low" reserves will bring remarkable economic effects for oil companies. Since PetroChina's IPO, economic limits for development investments and operation costs in oilfield companies have been specified definitely to ensure high rate of return on investment and maximize shareholder's value. Within these limits, only high grade oil reserves with low cost per ton of oil can be produced normally while the "Three Low" reserves with high early investment and high operation cost can be produced hardly.
On the basis of study on the present status and future production trend of the "Three Low" reserves in PetroChina, this paper proposes following three view points through analysis and study on the existing economic provisions, operational modes and the existing national oil and gas laws, regulations and policies: first, production operator can take the advantage of the preference offered by the existing economic provisions in the "Economic Evaluation Methodology and Parameters for Petroleum Development Construction Projects" to reduce the early development investment and enhance the integral economic effects; second, by means of further flexible operation mechanism and amendment & completion of contract modes for cooperation, PetroChina will enhance the development extent of the "Three Low" reserves; Finally, the national macroscopic preferential policy for encouragement of rational development and utilization of the "Three Low" reserves will be proposed based on study on the national oil and gas laws and regulations, especially on the policy for oil and gas taxation.
Expanding Advanced Production Logging Operations to Short Radius Horizontal Wells
Authors: Kelder O. , Chatriwala S. A. , Ma S. , Al-Shammari F. , Fontanilla J. P. , Al-Towijri A. , Al-Shammari B. , Murray A. K. , Herz U. 
Published: December 2007

Abstract
This paper discusses the first successful coiled-tubing-conveyed production logging operation in a short radius horizontal well in Saudi Arabia. The production logging tool (Polaris[TM]) was modified with knuckle joints to pass through the severe well dogleg of 58 degrees per 100 ft in openhole. Subsequently, the tool was conveyed an additional 1400 ft in the horizontal section. The logging objective was to determine the flow profile for oil and water and identify the water entry points. The major challenge was tool deployment in this short radius well to gain access to the horizontal section. Monitoring of short radius horizontals has been almost nonexistent due to high dogleg severity. Because of the rigid tool length of conventional production logging systems, tool modifications were crucial and extensive job planning preceded the operations. Planning included modeling maximum rigid tool length, tool modifications, simulations for job feasibility with 1.75 in coiled tubing, and tool string bending moment tests. Prior to the main run, a dummy tool was successfully conveyed through the high dogleg to determine the feasibility of the operation. The successful completion of the log allowed the generation of a flow profile and identification of the major fluid entry poiints. These will help determine the most efficient way of sidetracking wells in the Ghawar Field to maximize reservoir sweep efficiency and to aid in planning future short radius horizontal wells.
A Case Study of a Successful Matrix Acid Stimulation Treatment in Horizontal Wells Using a New Diversion Surfactant in Saudi Arabia
Authors: Chatriwala S. A. , Al-Rufaie Y. , Nasr-El-Din H. A. , Altameimi Y. M. , Cawiezel K. 
Published: December 2007

Abstract
Matrix acidizing of horizontal and multi-lateral wells is a challenging taskfor several reasons. First, oil reservoirs are heterogonous in nature and thepresence of high permeability streaks is common. Proper diversion technique isalways required to better distribute the injected acid across the target zone.Secondly, stimulation of horizontal wells requires injection of large volumesof acids. This will require using an effective corrosion inhibitor package thatcan protect down hole tubulars and coiled tubing, especially in sourenvironments. Thirdly, recovering large volumes of spent acid is a concern,especially in tight formations. Acid treatments should be designed to addressthese issues in a cost effective way.
Currently, there are a limited number of chemicals that can divert the acidinto the formation. This paper introduces a new viscoelastic surfactant whichwas used to form stable foam during matrix stimulation of a seawater injector.The length of the target zone was 1,500 ft, and the average permeability of thecarbonate was 700 mD. A 1.75-inch coiled tubing was used to better distributethe acid in the open hole section (6.125-inch in diameter).
As with previous viscoelastic surfactant systems, the surfactant moleculesform structures in solution in the presence of salts. These structures enhancethe viscosity of solution significantly and can be broken by dilution withinjection water or by adding mutual solvent (3-5 vol%) to thepreflush/postflush stages.
Unlike previous viscoelastic surfactant-based systems, the new surfactantbuilds viscosity faster and its gel breaks down in a shorter period of time.
This paper examines the results of extensive lab testing that led to thedevelopment of this improved self diverting system. It will also give detailsof the first field application of this system. Following the acid treatment,the well injection rate improved by five folds, from 16,000 to 80,000 BPD.Benefits and improvements introduced by the new diversion technique will bediscussed in detail.