bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Directional Drilling With Liner Systems Allows Logging and Directional Control While Getting Casing Across Trouble Zones
Authors: Srinivasan A. , Frisby R. , Talbot T. , Paraschiv M. 
Published: July 2010

Abstract
In deepwater and other challenging environments, operators often have to drill through ‘problem zones.’ These zones could be rubble zones, tar zones, or just unstable pressure zones. In the past, operators often had to drill through these areas, lose drillstrings, and drill a sidetrack, hoping that they might be able to avoid these areas the second time. But with the advancement of steerable drilling liner systems, we now have a solution in place to tackle the toughest drilling challenges. With much of the equipment coming from field-proven technologies, the next generation of steerable liner systems is increasingly proving to be the answer to reducing nonproductive time. This technology will allow operators to drill well sections directionally with the liner string as part of their normal drilling operations and case off that section all in one trip. This paper highlights these steerable liner systems and illustrates their ability to outperform conventional casing while drilling systems.
A Study on Deliverability Ratio Relationship between Horizontal Well and Vertical Well
Authors: Luo Yinfu , Zhu Guojin , Sun Fujie 
Published: July 2010

Abstract
The empirical range of deliverability ratio between horizontal well and vertical well is usually regarded as 2–5. But actually, this range is too large and the real ratio may not be within it. To quantify the deliverability ratio relationship between horizontal well and vertical well more accurate, the deliverability ratio relationship is derived based on modified Joshi's horizontal well deliverability formula and vertical well deliverability formula. Then as for different horizontal well lengths with known parameters of the pay zone in the vertical well where the horizontal well locates, corresponding deliverability ratios can be obtained. And then the horizontal well deliverability can be predicted by multiplying the known appraisal well (vertical well) deliverability and the deliverability ratio.
Sensitivity analysis between the deliverability ratio and relevant parameters is done by using pay zone, fluid and well parameters of Q oilfield of China Bohai Bay. The results show that as for different parameter combinations, the deliverability ratio can be within or without the range of 2–5; skin factor and off-center distance have little effect on the deliverability ratio, while as horizontal length increases, permeability anisotropy factor increases and pay thickness increases as well as drainage radius decreases, the deliverability ratio will decrease obviously. These regularities coincide with actual development regularity, which verifies the accuracy of the proposed method.
The proposed method quantifies the deliverability ratio range between horizontal well and vertical well, and increases prediction accuracy of horizontal well deliverability; therefore it is of great practicability, especially for early stage reservoir development.
Optimisation of Uncertain Structural Parameters Using Production and Observation Well Data
Authors: Irving A. , Robert E. 
Published: July 2010

Abstract
Conditioning of fault properties to production data is usually achieved by ad hoc modifications without consideration of prior probability distributions or physical realism. Here, we compare two geologically-based workflows for conditioning fault uncertainties to production data: a sensitivity analysis and optimisation scheme based on factorial experimental design and an alternative approach using the Ensemble Kalman Filter (EnKF). These methods have been tested on a producing reservoir whose combination of structure, well pattern and production history make it particularly suitable. The misfit between simulated and observed pressures was most influenced by reservoir volume (horizon depth, gas-water contact and fault positions) and inter-panel connection (fault juxtaposition and transmissibility). Using a response surface method, the best match to the observed data was obtained with a small connected volume and transmissible central fault. Application of the EnKF to fault displacement, permeability and thickness gave a similar match to the observed data; this was not improved by the inclusion of well oil production rate in the objective function. While comparable, the two optimisation methods each have different advantages and disadvantages. The method applied should be chosen in light of the particular field case and uncertainties being studied.
Mature Oil and Gas Fields: T*H*IN*K Process to Achieve Mature Field Production Excellence
Authors: Ondracek Walter , Liebl Werner 
Published: July 2010

Abstract
It is technically and financially a challenging task to produce mature assets economically, and mature oilfield operators like OMV have to stretch themselves to the limits to succeed: an average performance in delivering production rates, recoveries and CAPEX / OPEX spending will not be good enough - we have to arrive at ‘Production Excellence’.
In the past mature field operations have been built upon strong functional structures. Our approach and success was based on a hierarchical organisation and experienced people to run the field operations.
As OMV E&P started to introduce business processes in the late 90ies, our processes supported the old system: thinking remained functional.
Today, however, we look for ‘Production Excellence’, which does not only mean first class performance in operations but also effective control of cost and production, continuous identification and realization of opportunities to increase the value of our assets and finally the improvement of the Key Performance Indicators (KPIs) of our activities.
To achieve this, we developed a new Produce Process Management System which stretches across organisational boundaries and assures that everyone in the organisation sees the full picture. We closely cooperated with operational key personnel to define a new process, which provides the link to organisation, supports collaboration and integration of disciplines visualizes and controls information flow, and measures time and cost of process activities.
The Green Approach in Downhole Workover Operations
Authors: Liu He , Ye Peng , Chen Xianjin 
Published: July 2010

Abstract
This paper displays a new approach in downhole workover operations. Environmental pollution was resulted from downhole workover operations, such as spills of crude oil and produced water. These accidents can pose safety risks to operations, and has direct adverse impact on local people daily lives, public health, and agriculture etc. Workover operations are strictly regulated by HSE Management Standards.
After many years of practices, a series of multi-purpose clean downhole workover technologies have been developed and many types of equipment have been created, such as movable produced water treatment technology, to prevent spills of oil and produced water. These technologies and equipments have guaranteed green downhole workover in Daqing Oilfield.
Evaluation of the Petrophysical Properties of a Carbonate-rich Caprock for CO2 Geological Storage Purposes
Authors: Tonnet Nicolas , Broseta Daniel , Mouronval Gérard 
Published: July 2010

Abstract
Prior to any CO2 geological storage operation, the caprock's ability to prevent CO2 leakage must be carefully assessed. This ability is primarily related to the caprock's pore structure and to the interfacial properties of the caprock and the fluids in place, namely the brine that imbibes the caprock and the CO2 stored in the underlying reservoir. This paper reports an experimental effort to characterize some of these parameters, using as a working example the carbonate-rich caprock and reservoir conditions of the Rousse depleted gas field in the South-West of France, where an estimated 120000 tons of CO2 will be injected during two years. The parameters examined are: (i) the caprock wetting behavior in the presence of CO2, (ii) the caprock intrinsic (single-phase) permeability, (iii) the CO2 breakthrough (or displacement) overpressure, i.e., the minimum pressure difference between CO2 and brine required for CO2 to penetrate and flow through the brine-saturated caprock, and (iv) the caprock effective permeability to CO2 after breakthrough. The latter two parameters are indicative of, respectively, the caprock's capillary sealing efficiency and CO2 leakage rate once breakthrough has occurred.
The main observations and results are as follows. (i) The water-wet character of the Rousse caprock in the presence of CO2 in storage conditions is confirmed through a series of contact angle measurements on substrates. (ii) Single-phase (brine) permeability coefficients measured in steady-state conditions are extremely small and strongly sensitive to the effective stress, i.e., to the difference between the confining pressure and the pore fluid pressure. They do not exceed 20-25 nanodarcy (10-21 m2) for effective stresses below 4 MPa, and 1 nanodarcy for effective stresses in the range of 10 MPa and above. (iii) Gas breakthrough in two different brine-saturated caprock samples, using either CO2 or N2 as the displacing gas phase, occurs in one sample for a CO2 overpressure in excess of 7.6 MPa, and in the other sample for a N2 overpressure in the interval of 4.5-6 MPa. In the latter sample, the effective permeability to N2 after breakthrough is extremely low, below 1 nanodarcy; some "aging" effects are observed upon subsequent resaturations with brine and CO2 breakthrough experiments, with a CO2 breakthrough overpressure lower than expected and an increasing effective permeability to gas, yet still lower than 2 nanodarcy after two consecutive brine resaturations and CO2 breakthroughs.
Seismic History Matching of Nelson using Time-lapse Seismic Data: An Investigation of 4D Signature Normalization
Authors: Kazemi Alireza , Stephen Karl D , Shams Asghar 
Published: July 2010

Abstract
History matching of a reservoir model is always a difficult task. In some fields we can use time-lapse (4D) seismic data to detect production induced changes as a complement to more conventional production data. In seismic history matching we predict these data and compare to observations. Observed time-lapse data often consists of relative measures of change which requires normalization. We investigate different normalization approaches, based on predicted 4D data, and assess their impact on history matching.
We apply the approach to the Nelson field in which four surveys are available over nine years of production. We normalize the 4D signature in a number of ways. Firstly we use predictions of 4D signature from vertical wells that match production and derive a normalization function. As an alternative, we use cross-plots of the full field prediction against observation. Normalized observations are used in an automatic history matching process where the model is updated. We analyse the results of the two normalization approaches and compare against the case of just using production data.
The result shows that when we use 4D data normalized to wells, we obtain 49% reduced misfit along with 36% improvement in predictions. Also over the whole reservoir, 8% and 7% reduction of misfits for 4D seismic are obtained in history and prediction periods respectively. When we use only production data the production history match is improved to a similar degree (45%) but in predictions, the improvement is only 25% and the 4D seismic misfit is ten percent worse.
Finding the unswept areas in the reservoir is always a challenge in reservoir management. By using 4D data in history matching we can better predict reservoir behaviour and identify regions of remaining oil.
An Integrated Approach on Carbonate Reservoir Evaluation by Combining Borehole Image and NMR Logs - A Case Study in Ordovician Carbonate, East China
Authors: HuiJun Hou , HuaYun Yun , Yun Xie 
Published: July 2010

Abstract
This paper is a case study in an Ordovician carbonate, east China. Most carbonates are buried hill of Ordovician age and the reservoirs are dolomitized. Fractures are very important here as the porosity is often very low (about 2–5%). But the puzzle is the higher fractured zones not always are the higher production zones. So the two important things that one should be concerned with are (i) how to find the fractured zones, and (ii) the factors influenced the production rates.
An integrated approach using a combination of borehole image and NMR logs is applied in this study. Borehole images are used to extract fractures, vugs, rock textures and pore textures. Structure profile across the wellbore is created from the image dips as well, as an aid of the fracture analysis. NMR Bin data and T2 distribution spectrum are displayed to reflect pore textures, and a relative permeability also calculated from NMR logs. Furthermore, the morphic rock types are classified in details base on borehole images and lithology identified with other openhole logs. Nine morphic rock types are identified. All the summary data are displayed in one integrated plot for thorough analysis. The reservoir properties are found well related to morphic rock types and pay zones are observed located near the fault zone. Faults in one hand enhance the reservoir by dissolution on fracture and vugs near the fault zone, while in the other hand, it impair permeability of the fractures with clays in the fault zone. Those clay filled conductive fractures can be seen in borehole image, but no any permeable indictors in NMR data. The vuggy fractured dolomite is deemed as pay zone. The results are validated by the later well production. The combination of borehole image and NMR logs provide a valuable solution for clear understanding of this reservoir.
Outlook of Drilling/Production Equipment Managment and Rebuilding Techniques in Daqing Oilfield
Authors: Gang Cao , He Liu , Guochen Shi , Mingyan Lu , Mingzhen Liu , Honghai Wang , Yunlong Zhao , Bo Yu 
Published: July 2010

Abstract
Daqing Oilfield is the largest continental oilfield in China. After 50 years development, the total quantity of drilling and artificial equipments of the oilfield has reached to a considerably large size and it is still increasing with a higher rate. Daqing Oilfield had to spend a lot in maintenance and renewal of the equipments. For example, only the replacement of artificial lifting equipments would cost 156.75 million USD each year. In the past tens years, Daqing Oilfield invested huge funding to improve the equipment management and recycling manufacturing techniques. After years of study, a set of management methodology was created and a series of rebuilding techniques were developed. This paper presented the practices both in drilling and production equipment management and rebuilding techniques. This paper also decribe the outlook of oilfield equipment management and rebuilding techniques in the future.
Production-induced Stress Change In and Above a Reservoir Pierced by Two Salt Domes: A Geomechanical Model and Its Applications
Authors: Schutjens P. M. , Snippe J. R. , Mahani H. , Turner J. , Ita J. , Mossop A. P. 
Published: July 2010

Abstract
Production decreases the pore fluid pressure and increases the effective stress acting on the load-bearing grain-framework that makes up the reservoir. As a result, the reservoir deforms and compacts, and because it is connected to the rocks around it, there will be deformations and displacements in these rocks too. Well known effects are surface subsidence, wells damaged by shear, and timeshifts in 4D-seismic. Less well known is how the changes in the stress field itself should be taken into account in operations, e.g. to design infill wells and to plan production stimulation by hydraulic fracturing or waterflooding of the reservoir.
We present a geomechanical model for the initial stress field and production-induced stress changes in and around a steeply-dipping hydrocarbon reservoir penetrated by two large salt-domes. The model integrates 3D seismic and geological understanding, geomechanical data from wells and analogues, and depletion patterns from fluid-flow (dynamic) simulation. Our model results confirm published models of principal stress orientation in rocks pierced by salt domes. The depleted-model results show stress changes up to several MPa in magnitude compared to the pre-production stress state, but only limited changes in the stress orientations. The model highlights the influence of structural dip and time-dependent salt-sediment interaction on stress changes.
We then describe the application of the model in wellbore stress analysis for infill wells and in a water-injection scheme that has (we think) been severely impacted by injection-induced fractures propagating into the reservoir towards the producer wells. We explain how the latter application uses a 3D flow simulation model coupled to a dynamic fracture propagation model. The geomechanical model provides key input: stress magnitude and orientation. Results are validated against more conventional analysis of real-time pressure data.
In both applications, the integration of geomechanics in 3D static and dynamic models improved insight in the rock response to drilling and waterflooding, thus helping to optimise production.
Parametric Design and Application of Jet Pumping in an Ultra-Deep Heavy Oil Reservoir
Authors: Chen Shengnan , Yang Daoyong , Zhang Qi , He Jun 
Published: July 2010

Abstract
It is extremely difficult to produce heavy oil from an ultra-deep reservoir due to the long lifting path and the high flowing resistance in the wellbore. During its path to the surface along the production string, the reservoir fluid becomes more viscous resulting from heat loss and evolution of the dissolved gas, and thus movement of reservoir fluid slows down and stops at certain position inside the production string. In this paper, jet pumping has been selected and successfully applied to produce heavy oil from Lungu reservoir, Tarim Oilfield, with a maximum depth of 5950 m. Various power fluids have been examined for their capacities to reduce viscosity of the heavy oil in the production string. Hot water fails to reduce the viscosity of the reservoir fluid due to the significant heat loss along the wellbore, while adding chemicals to water (i.e., activated water) suffers from high material costs. Blending light oil with the reservoir fluid in the wellbore is found to optimally reduce viscosity of the reservoir fluid by more than 1600 times and has been applied in Lungu reservoir. Well configurations for jet pumping technique are designed and analyzed. A theoretical model is formulated to calculate the pressure, temperature, viscosity distributions along the production string, which are subsequently used to determine the key operational parameters, such as the quantity and pressure of the power fluid at the wellhead and the M ratio (ratio of the reservoir fluid to the power fluid). Sensitivity analysis indicates that the viscosity of the light oil and M ratio impose a significant impact on performance of the jet pumping. Field applications show that the jet pumping driven by light oil is a viable and efficient technique to lift heavy oil from the ultra-deep heavy oil reservoir.
Evaluation of Oil Compressibility Effects on Pressure Maintenance in Naturally Fractured Reservoirs Using Streamline Simulation
Authors: Tanaka Shusei , Arihara Norio , Al-Marhoun Muhammad 
Published: July 2010

Abstract
As naturally fractured reservoirs present wide ranges of geological characteristics and complex flow mechanisms between matrix and fracture, reservoir simulation is highly necessary to properly evaluate production performance. Pressure maintenance by gas and/or water injection is often required in naturally fractured reservoirs to control production GOR and to extract more oil from matrix rock. We studied by simulation particularly about effects of oil compressibility below bubble-point pressure on pressure maintenance and production performance.
We first developed and validated a 3-phase 3-dimensional dual-porosity model with the streamline method considering dissolved gas, capillary pressure and gravity. The fluid compressibility is a primary parameter that directly affects the reservoir performance. We accounted for compressibility effects with the total compressibility in the 3-D pressure equations, and with the effective density in the 1-D flow equations along streamlines. A flash-calculation algorithm was incorporated to treat the gas and oil phases correctly.
The oil and gas compressibility definitions presented by Perrine, that have been being used conventionally, have inherently a physical inconsistency such that oil compressibility below the bubble-point pressure increases with the increase of density, and that the mass of gas phase remains constant with changing pressures. To correct those, new derivation based on the basic compressibility definition was introduced.
Simulating peripheral water-injection with and without crestal gas-injection, results of pressure and production performance were compared for the new and conventional compressibility formulation. With the new compressibility, higher degrees of effectiveness were demonstrated in pressure maintenance. Gas injection also showed effectiveness in pressure maintenance, though it caused higher production GOR and a faster rise of water cut.
Finite Element Voupled Deformation and Fluid Flow in Fractured Porous Media
Authors: Lamb A. R. , Gorman G. J. , Gosselin O. R. , Onaisi A. 
Published: July 2010

Abstract
We present a finite element scheme which combines the dual permeability method (DPM) and the extended finite element method (XFEM) to simulate coupled deformation and fluid flow in fractured porous media. The scheme incorporates spatial variability in fracture properties without requiring the fracture to be discretized or aligned with the computational mesh. DPM is used to describe the fluid flow interaction between the porous matrix and fractures, whilst XFEM is used to address the discontinuous displacement field within elements which intersect fractures. The method is strongly coupled and solves the stress and flow equations simultaneously for each time increment.
DPM-XFEM uses the level set method (LSM) to define existing fractures and eliminates the need for their explicit discretization during simulation. The method performs well on coarse structured grids and does not require complex, difficult to generate meshes to conduct simulations. Comparison between the proposed method and the discrete fracture method (DFM) shows its ability to adequately determine the displacement and fluid pore pressure distribution within a fractured domain.
Friction Stir Welding: New Developments for Oil and Gas Industry
Authors: Steel Russell , Liu Qingyuan , Collier Matthew , Peterson Jeremy , Rowland Ray , Packer Scott 
Published: July 2010

Abstract
Friction stir welding (FSW) is a relatively new joining technology invented by The Welding Institute in 1991. The general use has been for welding soft, low melting materials such as aluminum. Advances in tool technology has allowed for the implementation of FSW into steel, stainless steel and nickel base alloys. The benefits of FSW include low heat input, elimination of solidification defects, the ability to join difficult and historically unweldable materials all while improving the mechanical properties over conventional welding processes. The oil and gas industry utilizes many specialized materials for performance and corrosion resistance. This paper will present and report progress on the different material properties and applications of FSW within the oil and gas industry.