bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Analysis on Subsalt Wellbore Stability in the Vioska-Knoll Deepwaters of the Northern Region of the Gulf of Mexico
Authors: Shen Xinpu , Bai Mao , Smith Russell
Published: July 2010

The goal of this paper is to present a best practice for deep water sub-salt wellbore stability analysis. Conventional one-dimensional analytical tools and three-dimensional nonlinear finite element method (FEM) software were used jointly in an integrated manner in which the former was used to predict pore pressure with logging data, and thus provides input data for FEM analysis. Numerical results of sub-salt wellbore stability analysis were presented for the Viosca Knoll field in the deepwaters of the Gulf of Mexico. To obtain accurate stress field information around the salt, it is necessary to begin by performing an analysis at the field scale. This analysis presents correct boundary conditions for wellbore stability analysis at the wellbore-section scale. Submodeling techniques were used to manage the field-to-reservoir scale discrepancy. A field model, 10 km in depth and width, was built, and a pan-cake-shaped salt body with a diameter of 7 km was embedded in the model. Trajectory optimization was performed once the vector distribution of principal stresses was provided. At the wellbore section scale, a submodel was built and the minimum safe mud-weight gradient was numerically predicted. A variation in the axial direction of the wellbore was performed to determine the optimized wellbore direction at the salt exit. The proposed integrated approach of jointly using conventional analytical tools with FEM software offers an effective method and best practice for deepwater sub-salt wellbore stability analysis.
Integrated Geology, Geophysics and Petrophysics Data to Describe Lateral and Vertical Reservoir Heterogeneity to Optimize Field Development Plan Limau Field, South Sumatra Basin, Indonesia
Authors: Nugroho Susanto Budi , Hartono Yedi , Ardianto Reza Nur
Published: July 2010

Limau Field is located in South Sumatra Basin, form as anticlinorium elongated from West – East. Limau Field are divided into 8 blocks and separated by normal fault and have been produce since April 1951. Description reservoir is needful in detail either lateral or vertical that can describe reservoir heterogenity in process designing and proposing a field development plan. Build a 3D model in Limau Field are challenge, which caused by complexity in stratigraphy and restrictiveness data. Integrated of multidiscipline science are needful to construct a static 3D model that can describe heterogeneity reservoir in Limau Field.

Interpretation detail in geophysics and geology were doing by integration between petrophysics and core data. Seismic enchantments are conducted to increasing a quality of 2D seismic data in Limau Field and used to build an attribute seismic Pseudo-GR and Acoustic Impedance. Attribute seismic pseudo-Gamma Ray and Acoustic Impedance map were used to describe generally in lateral distribution reservoir. Log data and Biostratigraphy were integrated to decide depositional environment furthermore the correlation geology was built by sequence stratigraphy concepts. Identification of lithofacies was built by integration between log data and petrography, and those data are applied to wells that have no in core data; it will be used to estimate a distribution of reservoir properties in throughout field. Analysis of log is use to found a reservoir properties which validated by core data. Synthetic of logs (Neutron & Density) are approach by neural network concepts then obtainable the sufficient data for analysis of log in wells that have incomplete log data. Relation between porosity, permeability, and vclay are using as phenomenon to define flow unit with the result that estimation of permeability can be done throughout field.

Fine geology model are build for 50 zones with total grid cell 97.886.742 with large scale of geology model; influences of variability regional toward reservoir quality can be seen. Application of geostatistic are use to build a model of lateral distribution and lithofacies vertical which guiding by attribute seismic map and facies pie from well as a trend and probability of distribution. Reservoirs properties are distributed by constrain sand zone and llithofacies. 25 of realization models are building by geostatistic application for each zone furthermore by blind test model is use as a validation of lithofacies distribution model and reservoir properties. Based on suitability of well production data then 5 final models have been chosen.
A Comparison of the Cultural Impacts on Leadership Preferences Between Overseas Chinese Petroleum Professionals and GLOBE Scores
Authors: Li Y. , America B. P. , Duncan P. , Green M.
Published: July 2010

From 1978 to 2008, almost 1.4 million of Chinese students have benefited from China's "open door (to the West) policy" and have studied in the U.S. and other Western universities. This group of scholars truly crossed the globe and brought with them diversity of culture from the East to the West. Among the Chinese professional group, the Chinese petroleum professionals have led the way for this movement. The purpose of this study was to meet the cross-cultural research and business needs in global business and leadership development. In particular, the study focused on a group of Chinese petroleum professionals who grew up in mainland China, were educated first in China (undergraduate level), immigrated to U.S., achieved higher education in the U.S. (graduate level), and have been integrated to U.S. society. This group of scholar-practitioners plays important roles in their organizations not only through technical expertise, but by also understanding first-hand the cultural impacts of globalization in the oil industry and the other organizations. This study focused on cultural and leadership behavior preferences of the study group and compares the global leadership preferences of this group against the reported Chinese culture and leadership scores in the GLOBE study. This research found significant differences between the two groups, and it further demonstrated differences between the study group's scores and the GLOBE study scores for the U.S., Taiwan, and Hong Kong. The comparisons attempted to establish the cultural impact of context on the leadership preferences from this focus group.
High-Temperature Conformance Field Application Through Coiled Tubing: A Successful Case History
Authors: Ramirez G. , Arredondo G. , Chapa J. , Macias R. , Soriano J. E.
Published: July 2010

Jujo Teco is one of the most important oil fields located in southern Mexico. It produces an average oil gravity of 35 API, which is combined with the heavy oil from offshore Mexico to enrich the Mexican oil blend. Sustaining oil production rates is one of the main targets for this mature field, and controlling the water produced is one of the primary challenges to keep the oil production up to the desired levels. Performing conformance treatments in this field is also a major challenge. Formations to be treated are naturally fractured carbonates averaging depths of 19,000 ft with bottomhole temperatures above 300°F. They are completed in openhole sections with typically 300 ft of exposed formation. It is especially difficult to address if the water-control treatments are bullheaded because there is no way to distribute and place the fluids in the right zone without the risk of sealing off the oil producing sections.

Using coiled tubing for placing these types of treatments has been a viable alternative to increase the rate of success on these deep, openhole completions in conjunction with the introduction of a high-temperature conformance polymer. The cases presented in this paper show how the water cut has remained almost zero in some instances, even when the treatment was performed three years ago.
Application of Heavy-Duty Wireline Fishing Tools and Techniques Solves Complex Problem and Restores Well to Production
Authors: Trujillo G. J. C. , Vincent J. M. , Robertson N.
Published: July 2010

The Oropendola Field is located in the Llanos Basin of Colombia and production from the wells is typically augmented by means of artificial lift methods, particularly the jet pump. During a recent routine wireline campaign to install a jet pump in a sliding sleeve, difficulty was experienced in releasing the assembly from the running tool and so it was extracted, but became lodged and eventually the running tool released leaving a fish in the hole. There followed several unsuccessful attempts to recover the fish but with each successive attempt the situation kept deteriorating and so fishing operations were suspended while the options were considered: Continue with fishing operations to try to clean up the well.Work the well over.

The latter option was considered financially unattractive so the former choice was made but the situation was so complex that it was decided to bring into the country a heavy duty Wireline fishing specialist to assist. His brief was to evaluate the well along with the client and the local wireline personnel, to put a plan in place for the recovery process to begin and to supervise operations to clean the well up. After a full review of the equipment available and the number and type of fish that needed to be recovered, an operational plan was compiled and operations begun using the on site wireline unit and ancillary equipment. Early problems with the relatively low strength of standard pulling tools lead to a further review of tooling and a set of heavy duty fishing tools being imported, upon receipt of which operations continued. After a total of 59 trips into the well, with no miss-runs and no failures, all of the fish were successfully recovered and a new jet pump assembly was run and landed successfully allowing the well to be brought back into production 26 days after arrival of the specialist on site.

In this paper the authors will review the operations that lead to the complex fishing problem, the tools imported and the reasons for them. They will go on to describe in detail the fishing operation which utilized equipment with lower than ideal load capabilities and the detailed evaluation process of each wireline tool string run which eventually lead to the well being cleaned up and its production capacity restored
Pioneer Coiled Tubing Intervention Onboard Floating Production Storage and Offloading Vessel (FPSO) Offshore Brazil
Authors: Pinto J. C. , Guimaraes Z. , Almeida V. A. , Raimundo L. S. , Bessa J. A.
Published: July 2010

FPSOs (Floating, Production, Storage and Offloading vessels) are ships with capacity to process, store and transfer oil. On the deck of the ship, there is a processing plant which separates and treats fluids from the wells. After separation, the oil is stored inside the vessel cargo tanks and, periodically, it is offloaded into a shuttle tanker through loading hoses.

The biggest FPSOs have capacity to process about 200 thousand barrels of oil per day. They are a good solution to develop exploration projects in offshore oil fields, especially in deep water, due to the comparatively low initial investment, short time for installation and great operational flexibility. However, FPSOs can experience problems arising from scale deposition in flexible sub-sea hoses.

Recently, in order to explore giant offshore oil fields in Brazil and to avoid the high installation cost of a great number of sub-sea pipelines, VLCCs (Very Large Crude Carriers) have been converted into FPSO's.

Over time, some of these converted floating plants have suffered production drops due to the obstruction of both production and gas lift lines by hydrate or scale depositions.

In many of these FPSOs, the reduced space and the lack of cranes in the areas close to the flow line access points were a barrier to restoring lost oil production. In some cases, it was necessary to shut-in production from some lines for several months to allow for the installation of a work-over rig. The financial consequences of such shut-in's were extreme.

In order to restore production faster and with lower cost, a pioneering method of intervention in FPSO production and gas lift lines was developed based on the use of coiled tubing.

This paper presents case histories of successful jobs that cleared two production lines and a gas lift line, including the description of logistics, rig-up process and operation of coiled tubing units in FPSOs. With minor modifications this method can be used in a wide variety of floating production vessels.

The FPSO is a floating, production, storage and offloading ship-shaped vessel. Production facilities are mounted on raised supports above the vessel deck. Reservoir fluids pass from subsea production wells, via flowlines and risers, up into the turret and then to the production facilities. Produced oil is stored in the vessel cargo tanks and periodically offloaded onto a shuttle tanker via a loading hose.
Lubricity of Brine Completion and Workover Fluids
Authors: Ke Mingjie , Foxenberg William
Published: July 2010

As the industry increasingly develops extended-reach, high-angle and deepwater wells, one of the considerations is fluid lubricity when designing a completion or workover fluid. Fluid lubricity plays an important role in choosing the optimum fluid for the operation.

This paper presents lubricity or coefficient of friction data for various completion and workover brines. Two commercial brine lubricants were also evaluated to determine their effectiveness in increasing brine lubricity. Results indicate that lubricity of brines varied with the type and concentration of salt, but generally increased with increasing salt concentration. For example, sodium and potassium brines behave differently as compared to calcium brines with regard to lubricity. Also, zinc bromide containing brines show very high lubricity, suggesting that using a lubricant is generally unnecessary. Furthermore, practical guidelines are provided to better design brine completion and workover fluids for well operations where reducing torque and drag is required. Case histories are also presented which successfully applied one of the lubricants in the fields.
Temperature and Salinity Effects on Drag-Reduction Characteristics of Polymers in Coiled Tubing
Authors: Shah S. N. , Vyas A.
Published: July 2010

Coiled tubing applications include drilling operations, hydraulic fracturing, well completions, removing sand or fill from wellbore, etc. These applications involve pumping fluids at high temperatures and salinity. Due to curvature effects in coiled tubing, huge pressure losses occur limiting the maximum flow rate achieved. By adding specific chemicals known as drag reducers to the fluids, these pressure losses can be minimized to a great extent.

Previously, several authors have published their results for fluid flow through coiled tubing but only a limited number of studies have been reported related to temperature and salinity effects on drag reduction in fluids flowing through coiled tubing.

This paper discusses experimental study of two commonly used drag reducers ASP-700 and ASP-820 flowing through coiled tubing with different salinities and temperatures. Both small-scale and large-scale flow loops have been utilized in this study. The small-scale flow loop includes a ½-in. OD smooth coiled tubing while the large-scale flow loop includes 2⅜-in rough CT. Elevated temperature tests and salinity tests are conducted using optimum concentrations of drag reducers in fresh water, 2% KCl, and synthetic seawater.

The flow data thus gathered were analyzed and used to develop correlations that can predict drag reduction at different salinities and temperatures. The developed correlations show reasonable agreement with experimental data.
Coiled-Tubing Intervention and Drilling System Using Cost-Effective Vessels
Authors: Millheim K. K. , Williams T. E. , Yemington C. R.
Published: July 2010

Deep water and ultra deep water intervention of wet trees has been a huge challenge for oil and gas producers. Currently, the only realistic way to do intervention is to use a conventional Mobile Offshore Drilling Unit (MODU) or intervention vessel (which is usually a smaller MODU) whether for a simple clean out or re-completing another producing interval. This is an extremely costly venture and the intervention is only scheduled when the economics of the operation are clearly justified. And even when the intervention is approved there is the problem of scheduling a MODU or intervention vessel. Sometimes the intervention can take months before a MODU or intervention vessel is available.

There is a new enabling technology, using a Self Standing Riser, (SSR), where a coiled tubing intervention and drilling system could be deployed by a cost effective vessel (not a conventional MODU) with all the coiled tubing and related equipment on the vessel. The SSR design is such that it would attach to the subsea tree and provide the support and a circulation conduit for the coiled tubing to have full circulation capabilities back to the intervention vessel. The vessel, itself, would have station keeping capabilities for a significant period of weather conditions for the Gulf of Mexico.

This paper presents the reasons why conventional and subsea coiled tubing approaches have been unable to provide a economically workable solution for coiled tubing intervention and drilling from wet trees in deep water. The paper describes a new system based on a SSR and a cost effective vessel (non MODU) design that could accommodate the coiled tubing equipment, and provide station keeping and support for the operations. The paper will discuss safety issues such as: the reliability and safety of the SSR, well control issues, emergency disconnects, and the event of a drive off by the vessel.

Unless, this type of technology is developed and deployed millions of barrels of barrels of oil and gas will remain behind pipe. In other cases, some fields will not be developed because the need for on-going intervention coupled with high capital costs that will not meet the economic threshold to commission the development.
Selective Fracturing of a Series of Perforations in a Horizontal Well Using a Resettable Straddle System
Authors: Thompson J. , Tomich M. M.
Published: July 2010

In the Viking formation in the Redwater Operations area of Alberta, Canada, horizontal wells are typically completed using slotted liners. Earlier wells were usually completed in the vertical and subsequent fracturing of the perforated interval would generally lead to productivity improvements. In a new horizontal well drilled early in 2009 it was decided to cement casing through the productive zone and then perforate several intervals and fracture them in an attempt to improve productivity. Fracturing of horizontal sections in the past has proved problematic with the use of diverters being ineffective and cup packers being unreliable, so a new approach to allow for selective treatment of each set of perforations was researched. As a result a selective “jet pack” straddle system was chosen which allows for setting it across the zone, fracturing, unsetting the straddle, circulating the well clean and providing for the possibility of moving it further uphole to treat the next set of perforations. The well was drilled to a total vertical depth (TVD) of 650 meters (2133 ft.) and a measured depth (MD) of 1481 meters (4859ft.), with a maximum inclination of 91°. A 4-1/2” 11.6lbs/ft casing string was then cemented in place and the well perforated with six sets of perforations each one meter in length with depths ranging from 817-1467 meters (2681- 4813 ft.). A straddle system was then deployed on 2-7/8” coiled tubing with the objective of selectively fracturing each interval with some 45 metric tones (99,180 lbs) of sand at pump rates of 12-16 Bbls/min with breakdown pressures ranging from 20-30 MpA (2900-4350 psi).

In this paper the authors will briefly discuss the history of the field and the evolution of the completion methods employed. They will go on to review the features of the straddle assembly and to describe in detail the selective fracturing operation which was performed in which the straddle was set and unset twelve times in six runs into the well. Productivity over the first 4 months was 50Bbls/Day, which is the longest & highest initial production rate in the field to date.
Scale Prediction and Inhibition for Unconventional Oil and Gas Production
Authors: Fan Chunfang , Kan Amy T. , Zhang Ping , Lu Haiping , Work Sarah , Yu Jie , Tomson Mason B.
Published: July 2010

With the advance of new exploration and production technologies, oil and gas production has gone to deeper and tighter formation than ever before. These developments have also brought challenges in scale prediction and inhibition, such as how to prevent scales at high temperature (150–200°C), pressure (1,000–1,500 bars) and TDS (>300,000 mg/L) commonly experienced at these depths. This paper will discuss (1) the challenges of scale prediction at high temperature, pressure, and TDS; (2) an efficient method to study the nucleation kinetics of scale formation and inhibition at these conditions; (3) the kinetics of barite crystal nucleation and precipitation in the presence of various scale inhibitors and the effectiveness of those inhibitors. In this study, nine scale inhibitors have been evaluated at 70–200°C to determine if they can successfully prevent barite precipitation. The results show that only a few inhibitors can effectively inhibit barite formation at 200°C. Although it is commonly believed that phosphonate scale inhibitors may not work for high temperature inhibition applications, the results from this study suggest barite scale inhibition by phosphonate inhibitors was not impaired at 200°C under strictly anoxic condition and in NaCl brine. However, phosphonate inhibitors can precipitate with Ca2+ in a brine at high temperatures and, hence, reduce efficiency. In addition, the relationship of scale inhibition to types of inhibitors and temperature are explored in this study.
A General Coupled Kinetic Adsorption/Precipitation Transport Model for Scale Inhibitor Retention in Porous Media: II. Sensitivity Calculations and Field Predictions
Authors: Vazquez O. , Sorbie K. S. , Mackay E. J.
Published: July 2010

This paper describes the application of a generalised kinetic adsorption/precipitation (Γ/Π) model for scale inhibitor (SI) retention and transport in porous media. The context of this study along with the chemistry and mathematics of the model itself are described in detail in the related Paper I (SPE 130702). Here, we describe a wide range of sensitivity calculations using this model which illustrate both (i) the consequences of this model in laboratory core floods, and (ii) the field predictions which results from various assumptions about field adsorption/precipitation processes. To our knowledge, this is the first time that such a dynamic coupled Γ/Π model has been deployed in this way to scale inhibitor transport modeling.

This model can describe any combination of retention mechanisms (adsorption and precipitation) in either equilibrium or under dynamic (non-equilibrium).conditions. The calculations presented here also clarify the roles of adsorption and precipitation mechanisms and how they affect field squeeze return curves. These results (and related experimental work, Kahrwad et al, 2009) show that precipitation is a more important process at higher SI concentrations going over to pure adsorption at lower concentrations. These modeling results indicate how we may then exploit the roles of each of these different mechanisms in the high SI and low SI regimes. Simulations of the type presented here can also help to provide the "target properties" for SI systems (adsorption, precipitation and coupled adsorption/precipitation) of the future.

This generalized model formulation also unifies the various approaches by different "schools of thought" by developing a scheme which can model any processes as appropriate. We believe that that this work resolves the controversy between adsorption vs. precipitation as the main mechanism of SI retention and replaces it with a clear generalised consistent model which may describe when (i) pure adsorption or (ii) coupled adsorption/precipitation occurs.
A New Approach to Propagate Petrophysical Properties in a Fracture Network for Naturally Fractured Carbonate Reservoirs Case Study: Icotea Fault Shear Zone, Cretaceous Formations at Maracaibo Lake, Venezuela
Authors: Rodolfo Soto B. , Perez Sergio , Arteaga Duarry , Martin Cinthia
Published: July 2010

A fuzzy-logic approach accurately characterizes spatial porosity and permeability for a complex, naturally fractured carbonate reservoir. The reservoir lies in the Cretaceous section alongside the fault damage and shear zone at the downthrown block to the west of the Icotea fault, Central North segment of the Maracaibo basin.

To identify the pore type in our characterization of this carbonate reservoir, we first used fuzzy logic to obtain fracture indexes from conventional well logs. Then we used a resistivity/porosity model with cementation factor, m, variable to determine fracture porosity, and calculated total porosity from neutron-density logs. After that, we developed a neuro-fuzzy logic permeability model with porosity, shale volume, fracture indexes, and pore type as independent variables.

Next, we used directional-statistics tool analysis to identify the five main fracture families and categorize them. The diagnosis of fracture orientation relies on the statistical analysis of fractures from four wells, three of them having image logs and one having a direct description of fractures from an oriented core. We also compared the fracture-orientation data from well data with the faults interpreted at seismic scale to unravel their structural connection.

Fracture lengths are obtained from curvature maps by direct measurement of lineaments matching the azimuth of each family. A logarithmic fit of the known values allows extrapolating values of fracture lengths and spacings below seismic resolution. To propagate porosity in our fracture system, where only a seismic P-wave volume was available, we found for each fracture family a general inverse functional relationship between fracture intensity and fracture porosity, introduced as the r-pi method of correlation.

With a sigmoidal function we correlate the neuro-fuzzy logic permeability variable with the aperture and intensity of the fractures. With a statistically based characterization we identify wheter the fractures display directionally or stratigraphically related anisotropies. Finally, to populate petrophysical properties in the fracture network we apply the functions devised starting with the size of the fractures as an independent variable.
Nipple Profile Milling With Electric Wireline Interventions
Authors: Schwanitz B. J. , Aji A. , Collins J. P. , Henriques K.
Published: July 2010

Recently, a solution has been developed to provide for milling of nipple profiles and other downhole hardware with electric wireline. A new milling bit and milling system for the wireline miller enables nipple profiles to be opened up in diameter to allow larger intervention products to be deployed, e.g. straddle packers and insert valves. Extensive testing was conducted prior to the introduction of this service to optimize the weight on bit and torque. The result was the development of a unique version of the hydraulic stroking tool to be combined with the milling tool to provide the controlled weight on bit.

A major benefit of using the wireline milling system is the ability to provide precision milling without mobilizing coiled tubing (CT) or heavy surface equipment for circulating and handling fluids. Thus, there is no risk of damaging the reservoir from the circulating fluids. In addition, this kind of intervention can be performed more cost-effectively, involving less people, less heavy lifts and therefore, reduced HSE risks.

The world's first milling of a nipple profile on wireline took place in Indonesia where the wireline miller was mobilized to enlarge the nipple profiles in 10 wells. The entire operation was performed in 20 operating days and well kills were prevented, which would have been necessary if executing the operation with a conventional method, such as on CT. Major benefits included minimal reduction in production levels, precision milling with zero cuttings left in hole and no labour-intensive requirement for CT or heavy surface equipment.

As of December 2009, the ID of twenty (20) Super 13 Chrome nipples have been enlarged for one operator, without a miss-run related to the new milling system.

This paper will discuss the technical aspects of this new milling system as well as present the field performance gained to date through a field test and two case histories.
Potential Implementation of Underbalanced Drilling Technique in Egyptian Oil Fields
Authors: Fattah K. A. , El-Katatney S. M. , Dahab A. A.
Published: July 2010

The need to increase productivity and to reduce drilling damage favors the use of underbalanced drilling (UBD) technology. In highly depleted reservoirs, extremely low-density fluids, such as foams or aerated mud, are used to achieve circulating densities lower than the pore pressure. In such cases, the induced modification of the in-situ stresses has to be supported mainly by the rock, with little contribution from the drilling fluid pressure. The application of underbalanced drilling depends on the mechanical stability of the drilled formation, among other factors. In general, poorly consolidated, depleted formations are not suited for that technology.

In this paper, twenty three UBD worldwide cases have been analyzed; two of which are from Egyptian fields and the others are from Iran, Algeria, Kuwait, Oman, Texas, Mexico, Indonesia, Canada, Libya, Middle East, Qatar, Saudi Arabia and Lithuania. From these analyses, the reasons of failure or success have been stated. The reasons of success included depleted reservoirs and highly fractured carbonates formation while, the reasons of failure include overpressurized shale, highly tectonic stress areas, and downhole failures. The main attractive application of this technology was proposed to be only in the reservoir section, and the target was to prevent the reservoir damage and hence increase the productivity and recovery factor.

A proposed underbalanced drilling program is developed based on these analyses to be used in the three main regions in oil and gas producing Egyptian fields. The aerated mud was selected as a drilling fluid to drill the reservoir section in Western Desert and Gulf of Suez region whereas the single phase fluid was selected as a drilling fluid in the Nile Delta region.
Mud Weight Design for Deviated Wells in Shallow Loose Sand Reservoirs with 3D FEM
Authors: Shen X. , Sikaneta S. , Ramadhin J.
Published: July 2010

Conventional mud weight designs are typically developed by using a 2D analytical solution. These methods, however, are unreliable in shallow, unconsolidated sands, which have very low cohesive strength and pressure-sensitive material properties, such as Young's modulus and Poisson's ratio. Using a 2D solution for these reservoirs can result in unnecessarily high mud weights and narrow mud weight windows, especially in deviated wells. In this case, a numerical method with a pressure-dependent material model becomes necessary for predicting a minimum safe mud weight. A fully coupled, nonlinear 3D finite element model for a shallow (1,000 ft TVD) horizontal well in Tambaredjo NW field of Suriname was built. The calculation of deformation of loose sand, which has pressure-dependent material properties, including cohesive strength, internal frictional coefficient, and Young's modulus, was combined with porous flow. We used this model to investigate wellbore stability and minimum safe mud weight gradient. Core samples from wells in the Tambaredjo NW field of Suriname were analyzed. The results of the analyses were used to develop a nonlinear relationship between material parameters, including cohesive strength, internal frictional coefficient, Young's modulus, and mean stress in effective stress space. Pattern of variation of these pressure sensitive parameters and other data were drawn from the multiple disciplines involved in the field development plan. The results of our study show the model-predicted minimum mud weight gradient required to drill the well without instability can differ from the conventional analytical solution by as much as 2 ppg. The use of this pressure-dependent material model for predicting minimum safe mud weight in shallow, unconsolidated sand reservoirs can result in significant savings in field development costs.
Design and Development of a Tubing Repair Solution Using an Expandable Metal Patch
Authors: Blane D. A. , Crossland A. J.
Published: July 2010

The paper presents a study of the design and development of a Hydraulically Expanded Tubular System (HETS) Internal Patch and Wireline Running Tool by READ Well Services, and qualification testing of the patch for oil and gas well applications. The HETS Internal Patch solutions enable tubing or other leaking downhole equipment to be repaired, or provide a method of strengthening corroded or damaged completion equipment.

The process involves expanding a metal sleeve (using hydraulic pressure) into the existing tubing to provide a continuous lining with a permanent seal. The restriction in the well is minimal (only the thickness of the patch) unlike straddle type solutions. A typical patch could be 5 mm (0.2”) thick. This allows the maximum possible production and for tools to be run through the patch for ongoing well maintenance requirements.

For a number of years HETS solutions, and their deployment systems, have been available to suit tubing sizes of 7” and larger. A Joint Industry Project (JIP) was created to downsize the technology to suit smaller sizes of tubing. READ Well Services and 5 major oil and gas sponsors used the inherent scalability of the available HETS technology and developed the SlimHETS system to provide a means of deployment for Internal Patches to suit 4 ½” to 5 ½” tubing. The deployment system was also required to be compatible with a tractor to suit high angle or horizontal wells. The project was created to develop, manufacture and test the the wireline deployment system and to design, manufacture and qualify corresponding Internal Patches.

The SlimHETS Internal Patch represents a new development for well design and offers significant advantages over alternative solutions. These advantages are further described in the paper.
Deriving Quantitative Fracture Properties from Whole Core Description: A Practical Link Between Geological Observation and Flow Simulation
Authors: Chen Jiajie (Jeff)
Published: July 2010

Fractured reservoirs have drawn more and more attention in the exploration and production business during the past decades. Oil and gas producers are now extensively worked on tight sand, carbonate, and shale reservoirs, all of which are impacted by the intensity and other properties of the fracture systems. When dealing with these reservoirs, two lines of advanced analyses need to be performed: fracture characterization and modeling.

This study explores the possibility of deriving quantitative fracture properties based on whole core description. The results show that in a given core slab, regardless of whether it is continuous or discontinuous, by making certain assumptions, it is possible to derive 0-D, 1-D, 2-D, and 3-D fracture intensities, estimate fracture porosity, and assess fracture openness and connectivity. The results can then calibrated with other geological and geophysical (G&G) data such as FMI and seismic interpretation (texture analysis, ant-tracking, and so on), and reservoir engineering analysis such as production ranking and well testing, possibly providing useful information for reservoir simulation and field development, as the permeability of fractures is closely related to fracture intensities and aperture. The methodology was applied to several producing fields in the Rocky Mountain area and it was concluded that adequate fracture assessment yielded consistent results between static and dynamic reservoir analyses. Although whole core is available only from certain intervals and certain locations of the fields, when integrated with regional structure, lithology, depositional facies, bed thickness, bed dip, and other data, the fracture parameters derived from cores generally provide a reliable assessment of the fractured reservoirs under evaluation.

This study provides a new workflow for quantitative fractured reservoir description, and application of such a data set to improve fractured reservoir simulation.
Recent Developments and Updated Screening Criteria of Enhanced Oil Recovery Techniques
Authors: Aladasani Ahmad , Bai Baojun
Published: July 2010

This paper reviews recent developments in enhanced oil recovery (EOR) techniques published in SPE conference proceedings for 2007 to 2009. It also updates the EOR criteria developed by Taber et al. in 1996 based on field applications reported in Oil & Gas Journal and at various SPE conferences. It classifies EOR methods into five main categories: gas-based, water-based, thermal, others, and combination technologies. New developments in EOR techniques, chemicals, and mechanisms are summarized to clarify advances in EOR criteria beyond previous limitations. Reservoirs that had previously been ruled out based on specific reservoir conditions are now candidates under updated EOR screening criteria. To demonstrate this potential, this work has established guidelines for the selection and optimization of chemical EOR methods for a specific reservoir.
Case Histories of International Partnerships for Training, Education, and Research Through Teams of NOCs, IOCs, and Universities
Authors: Van Kirk Craig W. , Baughman Gary L.
Published: July 2010

In order for universities to fulfill their roles and responsibilities to their many stakeholders within society, they must successfully address a multitude of tasks both internally and externally, domestically and internationally. This paper provides a summary of observations and recommendations, along with detailed examples, regarding successful collaborations and partnerships among universities, IOCs, NOCs, and other stakeholders, with a focus on the best practices in education, training, and research for petroleum engineering, geology, and geophysics programs within universities. Most of the experiences and conclusions presented address the university discipline of petroleum engineering (PE), with significant aspects tied to the other petroleum industry upstream E&P disciplines of geology (GE) and geophysics (GP). Most of the information and recommendations are widely applicable throughout the world, but emphasis will be placed on the experiences of the Colorado School of Mines (CSM) with partnerships in China.

The major theme is that while many traditional university programs and activities have been shown to be mutually rewarding to both universities and the industry, real success in these matters typically requires innovative collaborations between international universities as well as a stable relationship with one or more other partners. This additional partner, with a long-term interest in the success of the program, is essential in providing a continuous and adequate flow of financial resources, ensuring both the sustainability and long-term health of the university programs.

Also, the paper will clarify how all of the parties involved in these E&P education, training, and research activities can benefit from partnerships involving diverse international teams of experts, mentors, and students of all ages, thus demonstrating how PE-oriented entities can broaden and strengthen their collaborations with universities and other partners.
Development of the Next Generation of Phosphorus Tagged Polymeric Scale Inhibitors
Authors: Todd M. J. , Strachan C. J. , Moir G. , Aberdeen U. K. , Goulding J.
Published: July 2010

This paper reports a new method for the synthesis of phosphorus tagged polymeric scale inhibitors, laboratory based testing to validate these new molecules and their application in oil field reservoirs with comparison to existing commercially available technologies. Existing phosphorus tagged polymeric scale inhibitors are expensive to synthesise and result in low levels of phosphorus making detection difficult. With growing environmental concerns regarding incumbent phosphonate based scale inhibitor chemistries a shift to more environmentally benign polymeric scale inhibitors is required.

A new method for the synthesis of phosphorus tagged polymeric scale inhibitors has been developed. These novel molecules contain a greater level of phosphorus compared to existing techniques. This is achieved by polymerising new novel phosphonate monomers. These monomers may be polymerised or copolymerised with other species to yield phosphonate-functional polymers or oligomers. This results in highly detectable, environmentally friendly molecules with enhanced oilfield reservoir adsorption characteristics. These phosphorus tagged polymers are readily detected by ICP and HPLC techniques offering advantages over conventional phosphonate and polymeric scale inhibitors.

These new phosphorus tagged polymers have been developed as a range of new scale inhibitors to be deployed as down hole squeeze products. Due to their high detection by both polymer and elemental methods this makes them excellent candidates to replace both existing phosphonate and polymer inhibitors. The large range of monomers available allows the chemistries to be tailor made to specific wells and to a range of scaling conditions.

This paper will include laboratory evaluation of these new chemistries with coreflood data in comparison to existing chemistries. This new chemistry shows a significant step forward in the synthetic development of truly detectable phosphorus tagged polymers for an ever evolving industry.
How to Propagate Petrophysical Properties in a Fracture Network for Naturally Fractured Carbonate Reservoirs Case Study: Cretaceous Formations at Maracaibo Lake, Venezuela
Authors: Rodolfo Soto B. , Perez Sergio , Arteaga Duarry , Martin Cintia
Published: July 2010

A fuzzy-logic approach accurately characterizes spatial porosity and permeability for a complex, naturally fractured carbonate reservoir. The reservoir lies in the Cretaceous section alongside the fault damage and shear zone at the downthrown block to the west of the Icotea fault, Central North segment of the Maracaibo basin.

To identify the pore type in our characterization of this carbonate reservoir, we first used fuzzy logic to obtain fracture indexes from conventional well logs. Then we used a resistivity/porosity model with cementation factor, m, variable to determine fracture porosity, and calculated total porosity from neutron-density logs. After that, we developed a neuro-fuzzy logic permeability model with porosity, shale volume, fracture indexes, and pore type as independent variables.

Next, we used directional-statistics tool analysis to identify the five main fracture families and categorize them. The diagnosis of fracture orientation relies on the statistical analysis of fractures from four wells, three of them having image logs and one having a direct description of fractures from an oriented core. We also compared the fracture-orientation data from well data with the faults interpreted at seismic scale to unravel their structural connection.

Fracture lengths are obtained from curvature maps by direct measurement of lineaments matching the azimuth of each family. A logarithmic fit of the known values allows extrapolating values of fracture lengths and spacings below seismic resolution. To propagate porosity in our fracture system, where only a seismic P-wave volume was available, we found for each fracture family a general inverse functional relationship between fracture intensity and fracture porosity, introduced as the r-pi method of correlation.

With a sigmoidal function we correlate the neuro-fuzzy logic permeability variable with the aperture and intensity of the fractures. With a statistically based characterization we identify wheter the fractures display directionally or stratigraphically related anisotropies. Finally, to populate petrophysical properties in the fracture network we apply the functions devised starting with the size of the fractures as an independent variable.
CO2 Sequestration Monitoring in a Low Formation Water Salinity Reservoir
Authors: Murray Doug , Wang Yang Xing , Horie Tadashi , Yoshimura Tukasa , Mito Saeko
Published: July 2010

CO2 sequestration includes the injection of CO2 into permeable saline reservoirs. It has been shown that when water salinity is sufficiently high, in-situ monitoring of the CO2 front can be accurately described via traditional cased-hole time-lapsed Sigma (Σ) logging (Sakurai et al, 2005). However when the targeted reservoir's water salinity is not sufficiently saline uncertainty in the Σ approach increases and it becomes more qualitative than quantitative.

In this paper we summarize a CO2 monitoring project in Japan where formation water salinities were less than ideal for the pulsed neutron Σ based monitoring. To overcome this apparent complication, Σ and alternative measurements such as inelastic ratios and neutron porosity were acquired and combined with the open-hole resistivity, neutron-density and magnetic resonance logs to derive a robust interpretation.

The Hydrogen Index (HI) of CO2 is zero, hence neutron porosity in the presence of CO2 is low. In the presence of CO2 the carbon oxygen ratio (COR) is high due to changes in the carbon and oxygen yields.

The operational sequence of events involved the following; i.) resistivity, neutron-density and magnetic resonance logs were acquired in open-hole; ii.) well was completed, perforated and CO2 injected; iii.) pulsed neutron log data was acquired; iv.) saline water was injected and; v.) pulsed neutron log data was re-acquired.

The combined use of open-hole resistivity, neutron-density, magnetic resonance and cased-hole pulsed-neutron logs demonstrated that accurate CO2 front monitoring is viable in this relatively low salinity environment.