bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparison between Multi-Fractured Horizontal and Fishbone Wells for Development of Low-Permeability Fields
Authors: Yu Xiance , Guo Boyun , Ai Chi , Bu Zhidan 
Published: December 2009

Abstract
Development of oil and gas fields with low-permeability reservoirs presents a unique challenge to the energy industry due to the low productivity of individual wells and the high cost of drilling and fracturing a large number of wells. This study investigated the possibility of using fishbone wells to maximize the net-present value (NPV) of field development. A comparison of multi-fractured horizontal wells and fishbone wells for tight gas field development is presented in this paper.
Multi-fractured horizontal wells have been used to improve oil and gas production from low-permeability reservoirs for over a decade. The problems associated with this type of wells are well productivity decline due to fracture closure with time and uncertainty of fracture propagation due to the lack of knowledge of formation stresses. The disadvantages of multi-fractured horizontal wells may be avoided by using fishbone wells, a new technology developed in the recent years. In this study, we compared the net present values (NPV) of two development plans for a generic gas field using multi-fractured horizontal wells and fishbone wells. We found that these two types of wells can generate comparable NPV values. We conclude that as the drilling technology develops, use of fishbone wells with increased number of rib holes will be more beneficial than multifractured wells in developing tight gas fields.
Integrating Microseismic Mapping, Fracture Modeling and Reservoir Simulation Optimizes Well Performance in the Changqing Field
Authors: Liu Xinghui , Lolon E. P. , Li Xianwen , Chen Baochun , Cipolla C. L. , Wang Chengwang 
Published: December 2009

Abstract
The Changqing field consists of many individual oil fields that stretch across a large area in the Ordos Basin of north central China. Oil reservoirs in the Changqing field typically consist of stacked sand/shale deposits with the majority of the target zones having low permeabilities of 0.05 to 0.3 mD. All oil wells completed in these tight reservoirs are fracture stimulated to achieve commercial production. Fracture stimulation is also commonly done in injection wells to enhance injectivity in reservoirs under waterflooding. In a successful water injection program, it is critical to achieve optimal fracture parameters (fracture length, azimuth, and conductivity) for both the injection and production wells. Improper well placement and fracture design can lead to high injection pressures, early water breakthrough, and overall low oil recovery. This paper presents the results of two case studies to evaluate hydraulically fractured well performance of two oil reservoirs in the Changqing field. Microseismic fracture mapping was used to determine fracture geometry and azimuth. Fracture modeling was used to determine effective fracture length, height, and conductivity. The microseismic mapping and fracture modeling results were integrated into a multi-layer, multi-phase and multi-well reservoir simulator to determine the effectiveness of fracture geometry, conductivity and well placement on water injectivity and oil recovery for inverse 5-spot and rectangular drive water injection schemes.
Integrated Reservoir Characterization, Modeling and Simulation of Lower Sihapas in Kurau Field, Sumatra, Indonesia
Authors: Firmanto Tri , Suyatno Iman Suripto , Gomaa Ezzat , Priyantoro Jati , Sidik Benny , Pujiriyanto Andry , Ong Diana , Asmara Bondan , Rahmawan Irvan , Septiawan Henry , Gustiawan Eppy , Wibowo Arif 
Published: December 2009

Abstract
A 1000 bopd was achieved from successful integrated study of Kurau Field in 2007 year. All best practices of the study describe in this paper. The objective of this study is to build a complete reservoir model from an integrated study involving all aspects of engineering & G&G, such as data review, G&G modeling, reservoir characterization, reservoir modeling and prediction, in order to optimize the development of Kurau Field. The milestone starts from interpreting the 3D seismic data, structural or zonation model, petrophysics analysis, reservoir characterization, static modeling, dynamic modeling, and proceeds until it reaches the development and performance prediction of Kurau Field.
More than just a simple model, Kurau reservoir model resulted from all data and results from G&G such as interpretation of 3D seismic, G&G modeling (static model), environmental correction for well logs from Petrophysical Software analysis together with reservoir engineering works such as rock and fluid properties analysis, rock characterization and also production engineering aspects. Geomodeling software was used to build 3D seismic to reservoir modeling, with additional Simulation Software to complete the simulation.
The history matching analysis shows a satisfactory level of production profile comparison results of model performances with actual production data. Several infill wells and even EOR potential can be identified from this reservoir simulation model. Using an integrated study workflow from G&G, Petrophysic and Reservoir Engineering work had greatly improved the reliability of this reservoir model. Recently updated, those infill wells proved able to yield an additional 1000 bopd to Kurau field, as previously predicted.
An integrated study from Engineering & G&G Department was required when we attempted to build a reservoir model. Such a model can be used to determine infill well potential, work over result estimation and also the EOR project. Achieving an increment of the oil recovery factor is the most beneficial result from this reservoir simulation.
World's First Reverse-Port Uphill Openhole Gravel Pack with Swellable Packers
Authors: Jansen Rene , Koksaloglu Bengi , Holweg Philip , Hamedi Riehdwan , Dawson Mark , Chay Bryan , Mok David , Razien Ali 
Published: December 2009

Abstract
Brunei Shell Petroleum operates the Seria North Flank (SNF) field in Brunei Darussalam. When accessed from a land location, this near shore development requires that wells be drilled and completed at angles of up to 127 degrees to optimally develop the field.
The wells are drilled from Brunei's coastline under the South China Sea intersecting the SNF fields while targeting the optimum points of recovery within the reservoirs. These "fishhook wells" require sand control over long uphill reservoir sections as well as a viable economic delivery method. Current sand control methods were deemed unlikely to succeed in this environment and as such these complicated uphill wellbore trajectories required the development of a novel, reverse-port gravel-pack system.
This paper will discuss the gravel-pack system and how it addressed the difficult scenarios, including: How the openhole horizontal well was gravel packed from "toe to heel" as opposed to the conventional "heel to toe" method.Requirements for a tailored solution to carry the fluid through the system without bridging off in the workstring, washpipe or openhole sections.Well production and reservoir control
The multi-layered reservoirs required a form of open-hole and internal zonal barriers in order to efficiently control the production of each zone. Swellable packers were used in both environments to assist in providing the selectivity of zones.
In addition to these solutions, a delayed filter-cake removal system was used to clean up the polymers and filter cake in the open hole prior to production. Management and control of production of the multiple oil and gas zones is provided through the use of an intelligent completion system. These combined technologies enabled fully integrated well and reservoir management.
The world's first successful reverse-port uphill gravel pack in a fishhook well was completed in August 2007. The details of the design of a reverse-port gravel-pack tool, fluid analysis, flow-friction behavior, filter cake testing, gravel-pack installation, and well performance results of this and other similar completions will be provided in this paper.
Was that Last Project a 'Near Miss' or 'Miles Wide of the Target'?
Authors: Adam Peter 
Published: December 2009

Abstract
This paper is a case study on improving the quality of project approval decisions within an operating oil and gas company, by improving the existing deterministic economic evaluation workflow to answer questions such as: Did our project outcomes meet our expectations, or were we miles off?What, no production? A write-off! How could this be?Do we give the project team a bonus this year?
The methodology employed was to: Determine the insights needed by decision-makers to improve the quality of project approval decisions, and post-project, to appraise the project team's performance.Update the existing evaluation workflow to deliver these insights.Measure the impact of the updated workflow in terms of project proposal quality, and actual verses proposed project outcomes.
The improvements from this simple and inexpensive workflow include: Fewer and better project proposals.Better project sanction decisions.Fast and focused project look-backs.More objective evaluation of project team performance.
Conclusions from this project are: Improved project sanction decisions result from using a probabilistic economic valuation.This method is straight-forward to implement, requiring management support but minimal expense, and is equally applicable for small and large companies.Visualising the entire range of project outcomes benefits all stakeholders:Project team members quickly identify key project drivers, allowing more time to investigate ways to reduce their uncertainty.
This workflow is extended to quantify the uncertainty in production and cost forecasts for annual and long-range budgets.
Time Lapse Neutron Logging Improves Formation Evaluation and Reduces Rig Time in the Gulf of Thailand
Authors: Whittlesey Karen , Logan James , Rossiter Huw 
Published: December 2009

Abstract
In Chevron's Gulf of Thailand ('GOT') operations, costs drive logging and formation evaluation. Programs for logging and evaluation are based on consideration of perceived value and the potential for comprehensive utilization. Well lifespan is short, and economics rarely provide for the use of higher technology at non-discounted prices. A recent business initiative recognized that oil vs gas fluid identification from logging measurements was a risk that should be mitigated providing a major opportunity to add value.
Historical experience has shown, that the diameter of invasion can be greater than twenty inches by the time a well is logged with wireline which is beyond the limits of investigation for density and neutron tools, rendering the interpretation of fluid types ambiguous in most hydrocarbon bearing sands in this basin. To reduce this uncertainty, comprehensive wireline formation pressure programs have been run to assess hydrocarbon gradients but because sands are thin and permeabilities are low these programs have had various degrees of success.
LWD (logging while drilling) neutron tools can obtain data prior to invasion. Overlaying the LWD neutron and wireline neutron reveals time-lapse differences between the logs, shows gas intervals, and confirms liquid-filled zones. The technique can also infer inflow permeability for some of the more shaley gas reservoirs. Positive fluid identifications have been confirmed by follow up wireline pressure gradients, NMR logs, and production tests.
This paper will show many great examples of the evolution of a good idea. It will also demonstrate the effective use of technology, the buy-in from drilling engineers, and value of information benefits to the asset teams. Logging programs in the GOT once thought to be static, have rapidly evolved with insightful technology and the demonstration of its value.
Inversion of Induction Logging Data Constrained by Fluid-Flow Simulator
Authors: Liang Lin , Abubakar Aria , Habashy Tarek 
Published: December 2009

Abstract
Induction logging technique is one of the important tools for determining the formation resistivity of the subsurface. The near-wellbore formation resistivity is affected by the invasion of water-based mud-filtrate if there is a salt concentration contrast between the mud-filtrate and the in-situ formation water. The flushed-zone resistivity (Rxo), the undisturbed-zone resistivity (Rt) and the diameter of invasion (Di) can be estimated from the interpretation of array induction logging measurements through a model-based inversion process. Conventionally, the inversion assumes a "layer cake model" with three-parameter (Rxo, Rt and Di) invasion model or with a four-parameter invasion model that incorporates a ramped transition zone.
In this study, we introduce a 2.5D inversion approach for interpreting the induction logging data. The inversion is constrained by using a multiphase fluid flow model (incorporating pressure data if available) which simulates the mud-filtrate invasion process and calculates the spatial distribution of the water saturation and the salt concentration, which are in turn transformed into the formation conductivity using a resistivity-saturation formula. In this way, the inverted invasion profile is consistent with the fluid flow physics and moreover accounts for gravity segregation effects. Jointly with the pressure data, the inversion estimates a parametric one-dimensional distribution of permeability and porosity.
Previous works either assumed that the mud-cake permeability is known and used the bottom-hole pressure as a boundary condition, or alternatively used an independent mud-cake growth and invasion model to calculate the dynamic invasion rate as a boundary condition to the fluid flow simulator at the wellbore surface. The dynamic invasion process is complicated and is affected by many factors such as mud properties, formation properties, geometry and drilling conditions. Hence, although possible, it is difficult to calculate the dynamic invasion rate. This study shows that it is possible to directly invert the mud-filtrate invasion volume from the fluid-flow-constrained inversion of the induction logging data. Moreover, this approach is not limited by the traditional interpretation of the formation test, which is based on a single phase model without taking into account invasion or assumes that the mud-filtrate has been cleaned up from the formation testing zone. The joint inversion of the induction logging and pressure data demonstrates the ability to provide a more reliable interpretation of formation permeability. The advantage of the approach presented here, is its possible generalization to three-dimensional geometries, for example dipping beds and highly deviated wells.
Advanced Methods To Design and Interpret Exploration Well Tests - Two Case Studies
Authors: Carnegie AJG , Ball Stephen , Maizeret Pierre-David , Taylor David , Manh Ho 
Published: December 2009

Abstract
Two Drill stem tests (DST) were conducted from a well X, in an offshore field that was in the exploration phase. A major objective of each test was to identify whether the seismic anomalies seen between well X and a bounding fault act as impediments to flow. This objective was robustly achieved, together with all other test objectives, without unnecessary expenditure of rig time.
An expert had planned the tests using analytic models and his considerable experience. Pressure/rate deconvolution was used to support the interpretation. Since the tests were performed, a new method for DST design has been (recently) developed. It uses Experimental Design to enable systematic calculation of the expected chance of success of a DST when several scenarios exist for the reservoir. The method also provides a way to maximize these chances, given fixed resources, such as rig time.
The new method was tested against the actual plans used for the DST's in well X, and indicated that they were indeed optimal.
Experimental Design is rapidly gaining industry acceptance as a method to assess risks in field developments that arise due to reservoir uncertainty. But, its application to DST design when significant reservoir uncertainty exists, has rarely (if ever) been reported. The new method may exploit analytic models and/or finite difference simulation (coupled with geological modeling packages) to predict DST behavior. It is efficient and may be employed to rapidly redesign DST programs whenever new data becomes available, for example after open-hole logs have been acquired in a well to be tested. The cases described here illustrate why Pressure/rate deconvolution shows much promise to improve pressure transient interpretation.
Radioactive Sources in Petroleum Industry: Applications, Concerns and Alternatives
Authors: Badruzzaman A. , Barnes S. , Bair F. , Grice K. 
Published: December 2009

Abstract
Radioactive sources utilized in many industries, including the petroleum industry, have raised security, safety and environmental concerns. Oilfield sources are highly mobile, transported across the world and often used in remote locations. Despite safeguards and regulations, such sources have been lost, stuck down-hole, or breached. Concerns have been raised on sources being used in a radiological dispersal device (RDD). The US National Academy of Sciences, being concerned primarily with RDD, recently recommended replacing radioactive sources used in several industries with alternative sources. These include replacing Am-Be neutron sources used in porosity devices with either neutron generators which are switchable or with Cf-252 which would contain a lower amount of radioactivity. The lower risk Cs-137 source used in measuring density was spared at this time. However, a breached Cs-137 density source down-hole recently necessitated the setting up of a very long-term, elaborate monitoring program and thus such sources are of concern too.
This paper discusses the critical role of radioactive sources in petroleum exploration and production, protocols prescribed by regulators and the International Atomic Energy Agency for their safe use, concerns about their RDD potential, and lessons learned from a recent breached radioactive source incident in the field. The paper identifies additional procedures the oil industry needs to consider to use radioactive sources safely and securely, reviews the NAS recommendations and their potential impact on the industry, and describes alternatives to current chemical sources the industry is considering and the challenges which have arisen in making the transition.
Designing a Comprehensive Methodology as an AVO Analysis for Light Hydrocarbon Exploration Based on a Case Study
Authors: Parvizi R. , Norouzi G. H. , Sahabi F. , Maleki M. , Hajijomhouri H. 
Published: December 2009

Abstract
AVO (Amplitude Versus Offset) is one of the powerful methods in identifying the fluid type and lithology in subsurface exploration. In this paper, a comprehensive method has been designed which comprises of three parts: 1- Direct modeling 2-Inverse modeling 3- Cross plot interpretation. Each step has special roles. Direct Modeling can indicate the identity of attributes (lithology or fluid dependent attributes). The analysis has been done using both P-P and P-Sv attributes. Inverse modeling deals with real data and is fed from the results of direct modeling for characterization of the light hydrocarbon zones. The main role of cross plot interpretation is satisfaction of the results of the Inverse modeling and consequently increases the validity of them. This cross plot is also able to identify the lithology. Because of using Hodogram – Cross plot in this methodology, We able to manage the distribution of all points (anomalous and background points), So the small hydrocarbon zones is identifiable too. Distribution of points in wet zone is dense and in gaseous zone is expanded at Gradient – Normal Incidence Reflectivity crossplot. Using this methodology in Gorgan Plain (located in Iran) showed that fluid factor, SIGN, and possion reflectivity are fluid-dependent attributes. It also showed the normal incidence reflectivity and P-wave impedance reflectivity are lithology-dependent. Making the inverted sections of fluid-dependent attributes indicated two light hydrocarbon zones under the Cretaceous-Tertiary unconformity. It is expected that there is a wet zone under the one of this zones. Wet and gaseous zones are also satisfied by cross plot. Points distribution in cross plot of lithology-dependent attributes or fluid-dependent attributes is regular. Whereas considering simultaneous effect of both lithology and fluid attributes in cross plot results dispersive points distribution.
Estimating the Magnitude of Exhumation From 2D and 3D Seismic Velocity Datasets: A Case Study From Slyne Basin, Offshore Northwestern Ireland
Authors: Biancotto F. , Hardy R. J. J. , Jones S. M. 
Published: December 2009

Abstract
Exhumation describes vertical displacements of rocks from maximum depth of burial that results from the removal of overburden material. In this study we invert seismic velocity profiles from 2D and 3D seismic reflection datasets to constrain the distribution and the magnitude of exhumation within the Slyne Basin, offshore NW Ireland. The method has already been successfully applied to 2D datasets offshore Britain and Africa; this study is the first attempt to extract exhumation estimates from 3D seismic data. Inversion of 3D seismic velocity data yields a continuous map of exhumation across the entire 3D footprint. Exhumation estimates from 2D seismic sections agree with estimates from co-located 3D data. However, there is greater scatter in the 2D-derived exhumation estimates, most easily seen at line ties. This scatter in the 2D measurements arises because 2D seismic stacking velocities are less well constrained than 3D velocities. Together, the 2D and 3D seismic stacking velocity profiles can be used to estimate exhumation patterns on spatial scales &gt;10 km to an accuracy of ±200 m. Many estimated changes in exhumation are associated with geological structures, suggesting confidence in the results. The margins of Slyne Basin have undergone about 1 km more erosion than the basin centre to form the Jurassic-Miocene composite unconformity. Inversion anticlines in the centre of the basin have undergone a few hundred metres more erosion at their crests than at their flanks. There is good agreement between 3D seismic-derived exhumation estimates and existing exhumation estimates using traditional techniques applied to borehole data. Overall, our results show that regional exhumation can be mapped in hitherto unprecedented detail using good quality seismic stacking velocity data.