bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variations in Permeability of Coals-The Importance of Stress Path
Authors: Gray Ian 
Published: February 2011

Summary
This paper examines the factors which influence the permeability of coals with particular reference to coal stresses and mechanical properties including cleat spacing, Young's Modulus, Poisson's ratio and the effects of shrinkage caused by the loss of gas and water. This paper updates the work of the author in published in1983 (SPE 12514). The approach presented is mathematically based with reference to field examples and laboratory work. These include measurements of stress and permeability. The application of the work is in establishing how the permeability of a coal seam will vary during production.
The prime contribution is a theoretically sound, experimentally based, unified approach to determine the effective stress path and hence gain an indication of permeability changes through production.
Reservoir Pressure and Well Performance in Multi-well System
Authors: Khasanov Mars , Krasnov Vitaly , Musabirov Timur , Yudin Evgeniy 
Published: February 2011

Abstract
Novel simplified method of well performance calculation in multi-well system is considered. Differences between engineering content of various pressures in multi-well system traditionally denoted by one term "reservoir pressure" are shown. A new terminology to designate these pressures and estimation methods based on production and well test data are proposed.
In practice due to the complexity of well productivity analysis in multi-well system single well is often "extracted" from the environment. The influence of neighboring wells is taken into account by assigning for each well a certain value of reservoir pressure at the certain drainage area. At first glance, this simplification procedure seems so natural that does not require any justification. However, unlike the unambiguous and well-defined single well concept of "reservoir pressure", for wells in multi-well system this approach depends strongly on the context. In order to distinguish the concepts traditionally designated a single term "reservoir pressure" the definition of three types of pressure is introduced. Instantaneous and static reservoir pressures are the local parameters describing well performance subject to interference effects. The average (integral) reservoir pressure characterizes the energy state of the reservoir in whole. For the case of a single well system all these pressures are equal that creates the semantic difficulties in multi-well system consideration.
Reservoir pressures proposed can be used to provide well productivity calculations at different time periods after the change of well operation conditions. Instantaneous reservoir pressure enables to determine production rate changes at the end of transient flow regime and static reservoir pressure gives an estimation of production rate reached at the new steady state regime. The impact of well operation condition changes to the performance of surrounding wells can be also analyzed.
Innovative Design Features on PDC Bit Result in Record Run in Orenburg Region, Russia
Authors: Mortimer Laurence 
Published: February 2011

Abstract
The oil and gas fields in the Orenburg region are some of the oldest and largest in Russia. Drilling through carbonates with low mud flow rates is common in this region along with the associated challenges that these conditions present to polycrystalline diamond compact (PDC) drilling. This paper details how these conditions and others, were addressed as part of the design process culminating in a novel bit design with appreciably higher penetration rates and associated cost savings.
Having encountered a series of unusual dull conditions on PDC bits run in Orenburg, a systematic design approach was adopted in order to solve a series of specific regional issues resulting in new design features which lend themselves to other applications worldwide.
The team established that the best practice for drilling a particular vertical section in this region was to use a bent motor due to experiences of uncontrolled deviation close to total depth (TD). The objective was therefore not only to take into consideration the carbonate formation and flow rate issues, but also to establish the effect of the bent housing on PDC bits in order to improve the bit condition and overall performance.
Subsequent 3D CAD modeling and analytical studies enabled a common approach design solution for both bent housing and carbonate type applications. These studies, together with Computational Fluid Dynamics (CFD) analyses, enabled new innovative design features to be introduced into the bit to address hydraulics, formation and eccentric bit rotation. These new features resulted in far superior drilling performance and dull characteristics, which ultimately led to record runs being achieved in the region over a 1200m section of predominantly carbonate, inter-bedded formation.
The features would also prove to be transparent to the drilling contractor should they be running a bit on a straight or bent housing motor with low or high flow rates, thus acting to enhance the existing drilling practices in the region.
A New Model For Wellbore Stability And Stress Prediction In Underbalanced Wells
Authors: Moos Daniel , Perumalla Satya , Kowan Julie , Finkbeiner Thomas , Peska Pavel , Van Der Zee Wouter , Brudy Martin 
Published: February 2011

Abstract
We have developed a new analytical model for underbalanced drilling (UBD) that takes into account that rocks have scale dependent strengths, that the full stress concentration is not developed at a given depth in a well until sometime after the drill bit has passed, and that fluid flow into the advancing wellbore leads to a zone of locally lower pore pressure surrounding the well that extends beneath the drill bit. The model predicts regions within which compressive shear failure will occur and also provides predictions of where spalling (tensile failure) is a possibility. The results provide a more realistic and less conservative prediction of wellbore risk than models developed to study the stability of overbalanced wells. This new model can be applied to predict whether underbalanced operations are possible in a given well, and also the severity of wellbore instability as a function of underbalance. In addition, the model allows constraints to be placed on the in situ stress field (magnitudes and orientations) based on observations of wellbore failure in wells which have been drilled underbalanced. Wells designed utilizing model predictions were drilled without incident, and the model also provided reasonable predictions of the state of stress.
4D-Seismic to Support the Astokh Field Development Offshore Sakhalin
Authors: Boekholt Martin , Broker Koen , Bell Doug , Terwogt Dorine 
Published: February 2011

Abstract
In June 2010 Sakhalin Energy Investment Company Ltd. (Sakhalin Energy) successfully acquired a 4D seismic survey offshore Sakhalin covering the Astokh oil field development. This survey is the first 4D seismic survey carried out in Russia. The aim of this survey is to aid further field development optimization and infill drilling in the Astokh field, onstream since 1999. Rock property and 4D-seismic modeling studies indicated that hydrocarbon saturation and pressure effects can over time potentially be identified with 4D repeat seismic surveys. Feasibility studies were followed by the acquisition of a seismic test line in autumn 2009. This test showed amplitude and time differences at reservoir level in the seismic section when comparing the 2009 test line with the 1997 pre-production seismic survey. These differences can be correlated with the production history. Disturbances of seismic events were minimized by accounting for azimuthal velocity anisotropy during seismic data processing.
The proximity of the Astokh field development to the feeding grounds of the Western Gray Whales (WGW) offshore Sakhalin was fully taken into account for the planning and execution of this seismic survey. To this extent, Sakhalin Energy has benefited from collaborative efforts with independent scientific bodies and the Russian Government. This collaboration with recognized Russian and International scientific experts has yielded an exemplary set of monitoring and mitigation measures to protect the whales, whilst allowing responsible surveying activities to proceed without unnecessary delay. This includes: Execution of the survey as early as possible in the summer season, when the sea is ice-free and before the whale-feeding seasonReal-time measurement of acoustic sound generated at the edge of the feeding area to steer operationsStrict operating and shut-down criteria when WGWs are observed in the near-survey feeding areaContinued monitoring of distribution and behavior of the WGWs during and after the survey
New Methods and Treating Units for Electrical Dehydration and Desalting of Oil
Authors: Shvetsov Dr. V.N. , Yunusov Dr. A.A. 
Published: February 2011

In recent years, due to the switchover of the increasing number of fields to mature production stages characterized by high water cut and mineralization of wells production, and due to extensive involvement of heavier carbonic oils forming high- resistant emulsions into development as well, which is more significant, the problem of oil preparation for its refining becomes more pressing at a time, when the requirements for commercial oil have toughened.
Among all presently known methods of oil demulsification the most progressive and efficient ones are the methods of electrical demulsification [1, 2], used both at the stage of deep dehydration (as a rule) and at the stage of deep desalting under field and refinery conditions (always). Deep desalting of the oil coming from fields (up to 3÷5 mg/dm3 of salts) to Refinery, particularly, is achieved only with application of electrical dehydrators.
The Role of Fault Seal of Middle Miocene (Chokrak Formation) Fields at Northern Edge of West Kuban Trough in Fluid Migration Throughout Reservoir Development
Authors: Derduga A.V. 
Published: February 2011

Abstract
One of the basic objects of exploration works and hydrocarbon extraction in Krasnodar territory in recent decades are Chokrak depositions in the northern edge of West Kuban Trough. About twenty light oil and gas condensate deposits were discovered there. In the 90’s and 2000’s the major scope of seismic studies and drilling activities were concentrated in this direction.
Most of the fields discovered are related to tectonic (disjunctive) faults and deformational traps. Genetically disjunctive tectonics is represented by listric faults having their roots in middle-upper Maikop and their flattening in Sarmatian-Meotic stratum. Faults have great influence both on deposit formation, and on the process of hydrocarbon extraction. It is necessary to understand and forecast fluid penetrating ability of disjunctive dislocations in order to create and improve geological models both during exploration works, and in the course of field development. The estimation of breakdown pressure value sufficient for tectonic disturbance fracturing can be also used during drilling of wells with a view of reducing risks of drilling mud loss and loss of circulation.
New Approach in Real-Time Bit Wear Prediction
Authors: Rashidi B. , Hareland G. , Wu Z. 
Published: February 2011

Abstract
Challenging wells have been drilled recently utilizing advanced real time tools and techniques to optimize drilling operation while reducing risk and increasing safety. Moreover, the real time tools and techniques help identify upcoming drilling problems using real time data before they occur. Real time drilling analysis begins when real time drilling data are available and transmitted to the office locations via a remote server. The data can then be interpreted and analyzed by the engineers implementing various models for appropriate decision making. Lately, real time bit wear estimation has been a challenge in drilling a well to reach to the highest drilling performance and avoid bringing serious problems to the bit.
It has been shown that the combination of Mechanical Specific Energy (MSE) and drilling rate models can be used for real time bit wear estimation while drilling. As MSE does not take the bit wear effect into account while drilling rate or rate of penetration (ROP) models do, their difference can be used to monitor and identify bit wear status while bit is in the hole. This paper demonstrates a new form of a developed model to predict bit wear status while drilling which is built by combining rock energy (MSE) model with a newly developed drilling rate model for roller cone bits as well as a previously developed model for PDC bits. Rock confined compressive strength (CCS) is obtained from ROP models and used in conjunction with MSE values to predict bit wear trend. Several bit run sections from offset wells in Alberta, Canada were tested utilizing the model and final results are compared with the reported bit wear outs from the field. Encouraging results show that this methodology can be applied to detect changes in drilling efficiency by monitoring bit wear trend in real time while drilling.
Special Issues of Well Test Design and Analysis for Fractured Wells in Waterflood
Authors: Khasanov Mars , Krasnov Vitaly , Musabirov Timur 
Published: February 2011

Abstract
Novel approach to well test design and analysis for the wells with hydraulic fractures in waterflooded reservoirs is considered. General pitfalls and misuses of single well approach when applied to such systems are shown. It is revealed that for many practically important fractured wells cases conventional methods of infinite-acting radial flow regime identification are inapplicable. New technique of radial flow identification for such wells and capturing neighbor wells impact is introduced, practical examples are considered.
Approach proposed is based on the exact line-source solution in the form of integral exponent unlike the traditional method of interpretation which implies the logarithmic approximation. It is shown that for wells with highly conductive extensive fractures typical time of the beginning of logarithmic approximation can substantially exceed the actual time of the beginning of infinite-acting radial flow. In this case end of bilinear flow and beginning of radial flow can be estimated based on reservoir permeability assumptions or on comparison of the bottomhole pressure dynamics with exact line-source solution for a radial well with effective radius.
Utilization of Associated Petroleum Gas (APG) —the Norwegian Experience
Authors: Hinderaker Leif , Njaa Steinar 
Published: February 2011

Abstract
The goal of any petroleum producing country is to maximise the long-term social value of the hydrocarbon assets. To protect society's interests in development and operation of oil and gas fields, the Norwegian authorities have established frameworks for these activities, which are intended to ensure that the companies makes decisions that are also beneficial to the society at large.
In Norway the Norwegian Petroleum Directorate (NPD) has the authority to monitor the development of the different oil and gas fields and to ensure that the fields are being produced in accordance with best practice reflected in regulations and the framework established.
As for use of associated gas the regulation pertaining to proper utilization of the petroleum resources has been of paramount importance. In the regulations it is stated that flaring of petroleum is not allowed, unless in quantities needed for safe operation.
From day one the oil companies thus had to find a proper way of utilizing the associated gas. In most cases the gas was transported in pipelines and sold to the market, but in some cases there was no pipeline available and re-injection into the reservoir was the only option.
Improved recovery has been and still is of great concern for Norwegian authorities. Several initiatives have been made to evaluate the possibilities for improving oil recovery. The results of gas injection have been studied together with other methods for enhancing the oil recovery. For the Norwegian oil fields pressure maintenance by use of associated gas has proved to be very successful.
By the end of 2009 and since the oil production started on the Norwegian Continental Shelf in 1971 a total of more than 3526 million Sm3 of oil and 2138 billion Sm3 of gas has been produced. Most of the gas produced has been exported to the European market. Some gas has been used as fuel on the platforms and for transportation purposes and a small amount has been used in Norway as feed-stock for petrochemical plants.
Due to strict regulations and economical incentives just a minor part has been flared. However it is reported that gas in the order of 595 billion Sm3 has been re-injected into the reservoirs to sustain pressure and to enhance oil recovery. The average oil recovery factor for fields in production today is estimated to be 46%. It has been estimated that re-injection of gas so far has yielded an extra oil recovery of between 240 and 270 million Sm3 oil and condensate compared to the case without gas injection. If existing plans for further gas injection are executed, the total gains are in the range 320 to 360 extra million Sm3 oil and condensate.
Integrated Modeling of Fracture System and Evaluation of its Impact on Carbonate Heavy Oil Reservoir Performance
Authors: Ursegov Stanislav , Taraskin Evgeny , Chertenkov Michail , Habig Pierre , Ranjan Amit 
Published: February 2011

Abstract
In the Usinsk field located in the Timano-Pechora region of Russia, heavy oil is produced from vuggy-fractured carbonate Permian-Carboniferous reservoir. It has a more than 30 years history of operations and has produced mostly by natural water drive and in some pilot areas by hot water and steam injection. The presence of fractures highly affects the reservoir performance and is critical for current and new pilot projects of steam injection efficiency.
This study presents an integrated approach to characterize and model the fractures, and assess their dynamic impact in the south-west (SW) sector with 85 wells where new steam injection pads are being organized.
The approach included the detailed analysis of available core data, FMI logs, 3 D seismic, production data, well testing, etc, fully integrated by a unique advanced technology. The obtained results of the characterization allow developing the discrete fractured model of the SW sector which takes both into account the effect of seismic faults and several sets of diffuse fractures related to the fold structure of the reservoir.
The fracture model was then tuned and verified using the well test results to match KH and pressure responses. The end product was a 3 D model of the equivalent fracture parameters (permeability, porosity, and matrix block size) directly usable for the dual - porosity dual - permeability model reservoir simulation.
The conducted simulation runs confirmed the significant improvement of the history matching process using the created model and its applicability to clarify the effect of the fracture system on natural water flooding and steam injection results in the SW sector of the reservoir.
Effects of Pressure, CO2 Volume, and the CO2 to Water Volumetric Ratio on Permeability Change During CO2 Sequestration
Authors: Mohamed I. M. , He J. , Mahmoud M. A. , Nasr-El-Din H. A. 
Published: February 2011

Abstract
Carbon dioxide sequestration in underground formations is being considered on a massive scale to reduce the amount of CO2 emitted into the atmosphere. However, a better understanding of the chemical and physical interactions with formation fluids and rock is necessary before implementing sequestration in a depleted reservoir, aquifer, or during enhanced oil recovery operations. These interactions are affected by many parameters, including pressure, temperature, brine salinity, and CO2 injection rate. They can be evaluated by the change in water composition before and after injection, or from the change in CO2 injectivity over time. CO2 may affect the permeability positively due to carbonate rock dissolution, or negatively due to precipitation of reaction products, mainly CaCO3.
CO2 dissolves in the formation brine, generating carbonic acid, which dissolves carbonate rock. Dissolution impacts brine composition, which affects solubility. Calcium carbonate may tend to precipitate with changing concentration of bicarbonates. Precipitation may occur in either EOR operations or during primary CO2 sequestration. Injectivity changes are a concern during EOR operations, while storage capacity and seal integrity are primary concerns during CO2 sequestration. This paper addresses the effect of the pressure, injected CO2 volume, and the CO2 to water volumetric ratio during water alternating gas (WAG) operations on precipitation and the relative impact of dissolution or precipitation on the formation injectivity.
A core flood study was conducted using limestone cores. CO2 was injected under supercritical conditions at a pressure of 1,300 psi, and a temperature of 200°F. Core effluent samples were collected and the concentration of calcium ions was measured.
The results showed that the outlet pressure had the greatest effect on the bicarbonate presentation. Keeping the outlet pressure below the supercritical pressure of CO2 minimized precipitation of calcium carbonate. Additionally, maintaining the CO2/water volumetric ratio above 1.0, reduced bicarbonate formation in the formation water and helped in minimizing precipitation of calcium carbonate.
Further Developments and Application of a Real-Time Directional Drilling Digital Interface
Authors: Torres Russel , Gawski Victor , Snyder John , Kharitonov Alexander 
Published: February 2011

Abstract
This paper describes the further development of a real-time directional drilling digital interface (DDDI) that dynamically illustrates many aspects of the directional drilling process, specifically those that apply to positive displacement downhole drilling motors (PDM), rotary steerable systems (RSS), and motor driven rotary steerable systems (MD-RSS) while operating downhole.
The ongoing development of advanced drilling engineering packages and intelligent downhole drilling tools provides increasing amounts of available drilling-related data. The DDDI uses data supplied by means of an existing real-time, rigsitebased drilling information acquisition and database system to help to address many of the challenges encountered during directional drilling. The interface processes data based on engineering models, empirical knowledge, and technical data; it presents dynamic operating parameter information and graphical representations of functioning downhole drilling equipment. Subject matter experts located in diverse global areas can remotely access the interface to observe and to contribute to multiple drilling applications.
This paper provides details about the further development of the existing interface and its application to better optimize the real-time directional drilling process and to promote a balanced downhole system approach. The results have included reduced drilling equipment wear and damage, greater reliability, and reduced drilling costs.
In addition to downhole motor and rotary steerable system applications, the DDDI was used during downhole motor-driven rotary steerable system (MD-RSS) operations; benefits were realized through the simultaneous monitoring of both rotary steerable tools and PDMs.
After achieving real-time benefits in diverse global locations through the additional technical capabilities of the enhanced version of the DDDI, the potential benefits of a Russian language version were identified. The Russian language version enhanced the collaboration between English- and Russian-speaking personnel.
The most recent DDDI version aids in the comprehensive conceptualization, reporting, and control of directional drilling operations. It has a positive effect on the overall drilling process and expands the technical knowledge base, which provides additional support of the directional drilling expert system objective.