Publications
Browse our technical papers publications on a range of topics. Register for an account to access the full papers
WITSML Cloud Server
Operations Advisor
SOFTWARE APPLICATIONS
GEO - Geologists
WellXP - Administrators
WellSTORE - Administrators
INDUSTRY COURSES
Introduction to Data Management
Smart Workflows and Transition Management
Deriving value in IO through Data Analytics
Browse our technical papers publications on a range of topics. Register for an account to access the full papers
Our Recent Publications
AR/VR
Enabling Collaborative Decision Making Through Immersive Visualisation
SPE 191525, ATCE 2018, Dallas, 24 - 26 September 2018
Abstract
Virtual Reality (VR) and Augmented Reality (AR) are becoming increasingly popular in many industrial sectors but the uptake in oil and gas has, in comparison, been very modest. There is little doubt that these technologies will have a growing influence in our recreational lives over the next few years, as the hardware capability increases, costs decrease, and applications become more widely available. The real strength of these technologies is their capability to disseminate information to the user in a truly immersive experience. One area where this could be very valuable in our industry is in the support of drilling and production operations. Real-time Operations Centres (RTOCs) are now in widespread use but these suffer from high capital and operating costs, they are difficult and expensive to reconfigure and are often difficult to engage with from a remote location. Conversely, a Virtual Real-time Operations Centre (vROC) is low cost, can be configured quickly and decommissioned readily when no longer required. With modern networking configurations it is easy to connect from anywhere. This paper describes the first developments of a vROC.
Digital Transformation
“GEOSPATIAL DEEP LEARNING ENGINEERING ANALYTICS – CLOUD BASED B2B BUSINESS INITIATIVE”
19th Esri India User Conference 2018
Abstract
This paper discusses a cloud-based, B2B engineering analytical model setup for pipeline operators to analyse the pipeline integrity using AC overhead lines. The paper also briefly covers B2B business economics and their industry acceptability.
Deriving value in integrated operations through data analytics
DEW The Complete Energy Journal, September 2018
Abstract
Despite the wave of Digital Oilfield initiatives over the two decades around the turn of the century, the oil and gas industry has lagged behind others such as aviation and automotive in their widespread adoption of data analytics to revolutionize their business and operating models, according to Mr. Samit Sengupta, Managing Director, Geologix Limited.
“The Digital Oilfield – managing people transition”
GEO ExPro Article, vol.12, No.2, 2015
Abstract
It is well established that successful digital oilfield deployment projects require careful attention to ‘People’, ‘Process’ and ‘Technology’. We are very good at recommending technology solutions and after many years of operational experience in the oil and gas industry we can extend our expertise to recommend optimum workflows. But just how good are we all at managing the people transition? Maybe a few interviews with the stakeholders backed up with a couple of workshops will address the concerns?
If we are honest with ourselves, we know very well that this approach is woefully inadequate. If the operations staff, be it in drilling or production, do not buy into the digital oilfield workflows, then a very well designed Realtime Operating Center (RTOC) may become little more than a glorified meeting room. As for business value, this falls well below predictions and the overall digital oilfield project can unfortunately take on the personality of a very expensive failure.
Adopting Cloud Technology to Enhance the Digital Oilfield
IPTC Conference, Qatar, 7 – 9 December 2015
Abstract
The digital oilfield is a fundamental consumer of information technology. It requires the sourcing of reliable data, managing and storing that data effectively and serving it to operational decision makers. Cloud computing has forever changed the game in information technology. It could bring significant enhancements to the digital oilfield providing that the industry feels comfortable that data resilience, privacy and security are maintained. This paper looks at how to provide this assurance.
The big concerns with cloud computing are data loss and an uncertainty where the data is actually residing. Coupled with a growing number of security threats, these are holding back adoption in digital oilfield implementations. Some companies have introduced a "private cloud", which has enabled them to retain data within their own network boundary. However, this has prevented them from reducing their infrastructure costs and they have had to size their computing power and storage requirements to meet the highest level of demand, which may only be needed occasionally. Conversely, a public cloud enables a "pay as needed" service.
Achieving Digital Oilfield Competency
SPE 167432, Intelligent Energy 2013, Dubai, UAE, 28-30 October 2013
Abstract
Many oil and gas operators now see Digital Oilfield as a mature technology and yet there is still a broad spectrum of knowledge across the industry about what it is and how to derive a good return on investment. Much has been said about developing the "People??, "Process?? and "Technology?? sectors in parallel but even the most enthusiastic Digital Oilfield adopters would admit that it is the "People?? sector that gives them the greatest challenge. The big problem is how you engage the entire workforce, from senior managers to field technicians, in a technology with which only a few are really "hands on??. Many companies have chosen to ignore this problem and yet the entire workforce must be engaged, as the senior managers will be the financial decision makers and the field technicians will be the enablers of real-time data.
“DOF: devil is in the details”
Digital Energy Journal, Issue 29, February 2011
Abstract
Every reader of Digital Energy Journal knows that digital technology can help make well planning and drilling operations much more efficient, with better collaboration, things getting done faster, better understanding of risks, better decision making, better response time and more likelihood of hitting the payzone.
But you can’t just show your management a PowerPoint slide saying that, and expect them to greenlight a digital oilfield project, said Julian Pickering, director of Digital Oilfield Solutions and previously head of digital technology for drilling and completions with BP, at the Dec 9 Digital Energy Journal conference.
Drilling
Maximising the value of the Daily Geological Report
Operations Geoscience Conference, The Geological Society, London, 7-8th November 2018.
Abstract
Efficient utility of quality information is a key component of how we make decisions. Therefore, as we rely more on real-time decision making and collaborative technologies, every opportunity to update legacy workflows should be taken. The DGR is commonly created as a stand alone document, carefully created by manually entering values and statistics in a digital application. A PDF is then generated and shared around the organisation. This is both time consuming and digitally inhibiting. This case study shows how automation can plan a key role in data integrity, limiting the amount of manual intervention and occurrence of human error. Maintaining a useful digital format throughout the report's life-cycle is imperative for real-time decision making in online collaborative workspaces. As we move into an age where we will increasingly rely on data analytics to provide lessons learned and well review information from a well database, the unique information in a DGR should also be as easily leveraged as sensor data.
Post-drill analysis of Pore Pressure and Fracture Gradient from Well Logs and Drilling Events – An Integrated Case Study of a High Pressure Exploratory Well from Panna east, Mumbai Offshore Basin, India. Pore Pressure and Geomechanics from Exploration to Abandonment
AAPG Geosciences Technology Workshop, Perth, Australia, June 6-7, 2018
Abstract
Over-pressure, one of the important drilling hazards seen globally, is mainly associated with narrow operating windows resulting in severe well control incidents and lot of nonproductive times (NPT). Accurate knowledge of pore pressure is fundamental to any safe and economic well construction. Mumbai Offshore Basin, a pericratonic rift basin in the western continental shelf of India, covers about 148,000km2 from coast to 200m isobath, sedimentary fill ranges from 1100-5000m. It accounts for nearly two-thirds of the annual hydrocarbon production of India. The studied vertical exploratory well has been drilled in the Panna East area of Heera-Panna-Bassein tectonic block to explore the Panna formation (Paleocene-early Eocene).
Data Flow Management: Wellsite to Corporate Database - Case Study from ONGC WOB, Mumbai
SPG India, 2017
Abstract
In today's competitive exploration and production (E&P) atmosphere, the ability to exploit E&P data is the key to make informed, actionable decisions that support the vision and business strategy. How a company uses its E&P data can be the difference between average performance and competitive advantage. Companies tend to segregate their content into different data worlds that do not necessarily interact with one another and therefore fail to achieve integrity and maximum business value.
”Deriving Business Value from Implementing WITSML”
Russian Oil and Gas Technology (ROGTEC) magazine, Issue 022/04, October 2010
Abstract
The Wellsite Information Transfer Standard Markup Language (WITSMLTM) enables the upstream oil and gas industry to communicate wellsite information efficiently. The benefits for adopting a standardized approach to exchanging drilling information are intuitive for most drilling engineers and managers in the industry and usually include the following reasons:
» WITSML allows energy companies to leverage their investment in highly instrumented fields and enables new capabilities for automation and optimization that would otherwise be impossible or difficult to achieve.
» WITSML reduces the cost of information exchange between software applications within an operating company and between operating companies, joint ventures, partners, contractors, and regulatory authorities.
» WITSML reduces the cost of replacing or substituting software which results in improved functionality.
”WITSML Comes of Age for the Global Drilling & Completions Industry”
SPE 124347, Annual Technical Conference and Exhibition, New Orleans, Louisiana, USA, 4-7 October 2009
Abstract
The development of WITSML started in 2000 with the objective of building an XML standard for the transmission of wellsite data in a consistent form that would enable the integration of information from different suppliers. Energistics (formerly POSC) was involved from the outset and has provided independent hosting of the standard since early 2003. BP and Statoil were early sponsors and a Special Interest Group was formed. This has evolved steadily and today it includes representatives from all major energy and service companies.
”New Drilling and Completions Applications for a New Era”
SPE 112094, Intelligent Energy, Amsterdam, The Netherlands, February 2008
Abstract
Most of the existing drilling and completions engineering applications in use today were designed to compute snapshots at a single point in time for one user, rather than presenting the acceptable operating envelope and its associated constraints over time and supporting interaction of multi-disciplinary teams in collaborative environments.
The massive increase in data now available from real time sensors can make identification of critical factors more difficult and can hinder, rather than enhance the decision making capability and response to alarm conditions. Currently, interaction between individual team members is cumbersome and it takes place outside the applications. Teams are increasingly multi-cultural, which places additional demands on the human-computer interface and cultural and linguistic preferences need to be considered, particularly where collaboration centres span international boundaries. The applications are also part of a growing portfolio, including office and knowledge management tools. Their usefulness and efficiency depends on successful integration. In turn, this depends critically on standards. The working practices emerging from the use of these environments means the earlier applications are no longer optimised for the circumstances in which they are to be used.
“Design, Implementation and Operation of an Advanced Collaborative Environment for Enhanced Performance in Tangguh Drilling and Completions”
SPE 115511, Annual Technical Conference and Exhibition, Denver, Colorado, USA, September 2008
Abstract
The Tangguh Project in West Papua Province, Indonesia represents significant challenges in terms of drilling conditions, extreme remoteness, and social and environmental sensitivity. The Tangguh Drilling "Advanced Collaborative Environment?? (ACE) was designed to enhance drilling performance and safety. Very positive results were achieved within the first months of the drilling operation. This paper describes the design approach, implementation and subsequent operational experience of the Tangguh Drilling ACE. A number of features of this ACE have since become exemplars for BP's drilling operations globally.
The two-rig Tangguh development drilling campaign of 15 wells faced particularly difficult challenges with total losses, high vibration and the extreme remoteness of a location two timezones ahead of the office. To enhance drilling performance, an ACE was developed based on BP's global design principles covering people, process, technology, physical environment and organisation. The ACE connects each rigsite drilling team to the BP office in Jakarta and the onshore supply base. Real time drilling data in WITSML (Wellsite Information Transfer Standard Markup Language) format and high quality video conferencing were essential components to support the Wellsite Leader in the execution of the drilling plan.
“Energistics Standards Summit”
Digital Energy Journal, Issue 10, Page 28, January 2008
Abstract
Julian Pickering, responsible for new digital technology within the BP drilling and completions function, talked about his experiences driving the evelopment of WITSML at BP. "Talking about energy companies as a whole, we need to make WITSML attractive to all stakeholders," he said. "It's not about buying and selling but about working together so it benefits all." At BP there are several challenges to implementation," said Dr Pickering. "First there are human factors and politics, getting people to move on from past procedures." "Secondly BP has a unique structure that is very autocratic with multiple independent business units. There is no concept of a de facto standard; we have to work with each unit from scratch to present the business case."
"Finally we have to present a consistent message, some of the feedback is not positive which raises the argument in favour of different solutions. We have to speak with one voice so there is no doubt about what we are doing." "It becomes easier to persuade a business unit to use WITSML if you have stories of other BP business units who have used it to gain value," he said.
“A Standard Real-Time Information Architecture for Drilling and Completions”
SPE 110388, ATCE 2007, Anaheim, California, USA, 11-14 November 2007
Abstract
BP is looking to implement a standard data architecture for real-time drilling & completions information. This will enable us to make wider use of our collaboration centres through a common approach and will allow us to leverage the developing WITSML standard more effectively in our operations.
BP uses many different service organisations to deliver its global drilling & completions agenda. In the past, this has resulted in a lack of standardisation in real-time information flow. We have been unable to share data and expertise readily between different operating centres. Applying a common approach to information access on a global basis will enable us to streamline our operations and make wider use of emerging collaboration technologies.
Laying the Foundation for Increasing Efficiency of Intelligent Wellsite Communications
SPE 150278, Intelligent Energy 2012, Utrecht, The Netherlands, 27-29 March 2012
Abstract
When implementing an intelligent oilfield strategy it is tempting to focus on smart technology: advanced applications, novel instrumentation and collaborative environments. The data architecture is often overlooked. As deployments increase, it is important to review the industry data foundation and future direction.
WITSML version 1.4.1 is here and takes several bold steps to provide a robust, real-time foundation for data exchange and preservation. This version, the product of over two years of collaborative work by participants from oil companies, service companies and technology providers, is poised to be the keystone of the intelligent oilfield data architecture for wellsite communications.
WITSML 1.4.1 is simpler, more efficient and better defined than previous versions. It addresses several problems that hindered earlier versions by clearly specifying API behaviour and resolving ambiguities. It is also more prescriptive, which makes greater demands on software vendors but assures the one thing that matters most: interoperability. With a host of technical improvements, including new data objects, broader scope, data compression, query optimisation and change logs, version 1.4.1 will help increase the speed of information transfer and simplify use and deployment throughout the industry. To support WITSML adoption, Energistics is putting more emphasis on product certification and has initiated accredited training for developers and implementers.
Exploration
Evaluation of Coal Quality and Geomechanical Moduli using Core and Geophysical Logs: Study from Middle Permian Barakar Formation of Gondwana Coalfield
ICRMEG: 20th International Conference on Rock Mechanics and Engineering Geology, Sydney, Australia, Mar 29-30, 2018
Abstract
Middle Permian Barakar formation is the major economic coal bearing unit of vast east-west trending Damodar Valley basin of Gondwana coalfield. Primary sedimentary structures were studied from the core holes, which represent majorly four facies groups: sandstone dominated facies, sandstone-shale heterolith facies, shale facies and coal facies. Total eight major coal seams have been identified with the bottom most seam being the thickest. Laterally, continuous coal seams were deposited in the calm and quiet environment of extensive floodplain swamps. Channel sinuosity and lateral channel migration/avulsion results in lateral facies heterogeneity and coal splitting. Geophysical well logs (Gamma-Resistivity-Density logs) have been used to establish the vertical and lateral correlation of various litho units field-wide, which reveals the predominance of repetitive fining upwards cycles.
Geophysical log based coal characterization of middle Permian Barakar formation from North Karanpura coal field, India
Journal of the Geological Society of India, Springer, 2018, Vol 92, pp 36-44, Sydney, Australia, Mar 29-30, 2018
Abstract
North Karanpura coal field is the western most marginal coal bearing segment of east-west trending Damodar valley basin. It consists of middle Permian Barakar Formation with sandstone, siltstone, coal and shale being the dominant lithofacies, deposited in a fluvial meandering environment, giving rise to repetitive fining upwards cycles. Study of geophysical logs, the drilled core holes were used to identify lithofacies, correlate coal seams with splitmerge behavior; which has been used to understand lateral and vertical facies disposition. Geophysical logs have been employed to compute various coal assay parameters–ash, fixed carbon, moisture, volatile content, cleat porosity, vitrinite reflectance seam wise. Study of log based coal assay parameters, calibrated with lab based values depicts lateral coal quality variation, i.e. decreasing ash content, higher fixed carbon from east to west, which can be a great proxy for future development of field or mine planning.
Sequence Stratigraphic Model of Middle Permian Barakar Formation from a Marginal Gondwana Basin, India
Journal of Earth Science, Springer, 2018, Vol. 29, No. 4, pp 745-754
Abstract
Gondwana deposits are extensively found across the continents. Here we study the Middle Permian Barakar Formation from the marginal Gondwana Basin, eastern India, being deposited in a normal fault setting. Availability of extensive cores as well as geophysical log suites (gamma-resistivity-density from drilled wells) from the study area helped us achieving high resolution interpretation. Core study identifies fluvial sedimentary architectures, which were correlated with the geophysical logs and modeled field-wide to understand vertical and horizontal facies disposition. The facies analysis has been used to establish a sequence stratigraphic model of the cyclic Barakar deposition. Four major fining upward depositional sequences were identified, each sequence comprises of low accommodation system tract (LAST) at base and high accommodation system tract (HAST) at top. LAST is characterized by vertically stacked, multistory amalgamated channel sandstone dominated facies, while floodplain dominated facies characterizes HAST, reflecting a gradual shift from braided to meandering depositional system from bottom to top of each cycle. Study reveals depocenter to be in the western part, supported by eastward thinning of sediment packets, all being deposited in a half-graben setting.
Impact of Bioturbation on Reservoir Quality and Production – A review
Journal of the Geological Society of India, Springer, 2017, Vol. 89, Issue 4, pp 460-470
Abstract
Bioturbation is a typically small scale yet potentially significant geological process altering rock properties by reworking. For many years, bioturbation studies found application in exploration geology to estimate paleobathymetry, interpreting depositional environment and identifying key stratigraphic surfaces. These act as vital inputs to the geological models, for determination of source rock potential, reservoir quality and modeling of petroleum systems. Recently geologists extended the application of bioturbation studies to address production related challenges. Recognizing the bioturbation effects and incorporating them in reservoir simulation models can improve production predictions and enhanced oil recovery operations. This paper discusses bioturbation and its effects on reservoir quality, its performance and production.
Facies analysis and depositional model of Late Permian Raniganj Formation: Study from Raniganj Coal bed methane block, India
Journal of the Geological Society of India, Springer, 2016, Vol. 88, Issue 4, pp 503-516
Abstract
The Raniganj Formation (late Permian) forms the uppermost economic coal-bearing unit of the Gondwana succession. The dominant facies interpreted from analysis of cores from the Raniganj formation are classified as Sandstone dominated facies, Sandstone - shale heterolith facies, Shale facies and Coal facies. The natural Gamma response of Raniganj Formation shows predominance of repetitive fining upwards cycles. Integration of core analysis and geophysical log data of the Raniganj formation indicates meandering fluvial environment. The lower part of Raniganj Formation is channel dominated which corresponds to thick amalgamated sand bodies while the upper part represent overbank shows predominance of channel avulsion indicating a gradual change in accommodation space. Five major fining upward depositional sequences, bounded by sub-aerial unconformities (sequence boundaries) have been dentified in Raniganj formation, based on changes in depositional style that are correlated regionally. Each sequence comprises of Low accommodation system tract (LAST) at base and high accommodation system tract (HAST) at top. LAST is characterized by vertically stacked, multistory amalgamated channel sandstone dominated facies, while floodplain dominated facies characterize HAST. The coal seams deposited in LAST are thicker and relatively more continuous than the frequent thin seams of HAST. Such facies distribution study would be helpful for the development strategy for CBM blocks based on production priority.
Discussion on the concepts in palaeoenvironmental reconstruction from coal macerals and petrographic indices, Marine and Petroleum Geology
Elsevier, 2016, Vol. 73, pp 371-391
Abstract
Organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions. This allows the relation of coal composition to mire ecosystems or environments. Coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments. Many authors proposed relations between specific maceral assemblages and/or micro-lithotypes and peat forming environments. The key controlling factors which affect peat environment include hydrogeology, redox, pH, vegetation type, clastic influx, sedimentation and peat accumulation rate etc. Recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models. The main reasons for the failure of the petrographic models are – oversimplification of the effects of humification on tissue preservation vs. destruction, the use of post-diagenetic processes (e.g. geochemical gelification) in determining depositional environments, changes in petrographic composition related to floral evolution, geological age, rank increase and compaction, lack of distinction between different inertinite maceral in some models. Here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo-environmental reconstruction are discussed. A multi-disciplinary approach including petrography, palynology, chemistry etc. has been recommended, which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation.
Review on coal petrographic indices and their applicability in paleoenvironmental interpretation
Geosciences Journal, Springer, 2015, Vol. 20, Issue 5, pp 719-729
Abstract
Organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions. This allows the relation of coal composition to mire ecosystems or environments. Coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments. Many authors proposed relations between specific maceral assemblages and/or micro-lithotypes and peat forming environments. The key controlling factors which affect peat environment include hydrogeology, redox, pH, vegetation type, clastic influx, sedimentation and peat accumulation rate etc. Recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models. The main reasons for the failure of the petrographic models are–over-simplification of the effects of humification on tissue preservation vs. destruction, the use of post-diagenetic processes (e.g., geochemical gelification) in determining depositional environments, changes in petrographic composition related to floral evolution, geological age, rank increase and compaction, lack of distinction between different inertnite maceral in some models. Here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo-environmental reconstruction are discussed. A multi-disciplinary approach including petrography, palynology, chemistry etc. has been recommended, which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation.
Bridging the Industry-Academia Gap and Knowledge Management: Need of Hour
Paper ID-2009894
Abstract
Industry-academia interface has always been under extensive discussions in many ways. A developed common area of interest strengthens the relationship between universities or research institutes and industry in a bigger resolution and on a precise basis between scientists and professionals in industries. Management of knowledge and communication makes a sense of newer outlook of the hydrocarbon sectors. To boost the growth of oil and gas industry globally, trained workforce and continuous strategic methods are needed which is only possible through mutual conjunction of academic and industrial human resource. Shortage of high quality collaboration in reality climbs list of discussions these days. This article gives an insight on bridging the gap between academia-industry interaction for a better way of the look of oil & gas industry scenario. The most core sector of a research institute or a university is its teaching. Many of the institutes have really phenomenal high-end applied courses which is the subject that fascinates the industry. Industry looks for human resource with proper dimension of knowledge in the field. To rectify the theoretical knowledge into the practical industrial problems proper training is needed for the newly recruited trainee. The trainee plays the most important role in this system to establish the academia-industry relation. More and more involvement of undergraduate students with the industry makes a proper hit to reduce the gap. Another part of interest for the industry is the really outstanding faculties and scientists who are doing globally acclaimed research in the field of hydrocarbon and its sciences. Along with betterment of corporate level strategies industries need to have technological advancements, which are largely benefited by growing research. So, extensive collaboration with cutting edge researchers working on applied sciences is expected. In addition government should have a proper assistance for the synergy between academics and industry in the oil and gas sector to fuel the need of the hour.
Geo Pressure
Determination of Regional Stress Magnitudes and Directions: A case study on Offshore Exploratory wells of Tertiary Sequence in Kutch-Saurashtra Basin
GEO India 2018
Abstract
Excessive wellbore breakouts, wellbore washouts (uncontrolled borehole enlargement) frequent tight pull & held up, undesirable log quality in drilled wells, necessitates understanding the subsurface behaviour of the wells & basic cause of the problems. Rocks at depths are subjected to stresses resulting mainly from the weight of the overlying strata and the locked in stresses of tectonic origin. In-situ stress magnitudes and orientations play a very significant role in understanding the subsurface behaviour during drilling, reservoir modelling, well stimulation and production optimization.
Geomechanical analysis for feasible CO2 storage in an Indian mature oil field
SPG India
Abstract
Geomechanical assessment is a very vital step in geological CO2 storage project to minimize the potential risk for CO2 leakage through fracture pathways and fault re-activation caused by CO2 injection. A good monitoring system of geomechanical properties such as in-situ stress, rock stiffness and strength could actually control the potential CO2 leakage pathways. Moreover, a safe and successful storage practive requires wise selection of suitable wells, especially in mature oil field.
Issues Faced while Calculating Overburden Gradient and Picking Shale Zones to Predict Pore Pressure
1st EAGE Workshop in Pore Pressure Prediction, Pau, France, Mar 19-21, 2017
Abstract
Over-pressure is one of the important drilling hazards seen globally. Estimates of over-pressured zones/locations and over-pressure magnitudes have a direct impact on well drilling and completion. Overburden gradient (OBG), Pore pressure (PP) and Fracture Gradient (FG) are the three basic outputs of any pore pressure analysis. OBG is calculated from density (RHOB) log data. As density log data does not start from surface/seabed, we use several equations to compute shallow section pseudo-RHOB and integrate it with LWD/wireline RHOB log data. This article discusses the issues with various ways to fill the data gap of shallow section density. PP is normally predicted against shale zones and then calibrated with the most reliable and direct pressure measurements against sands and log data from adjoining shales. This paper also addresses the various issues faced while picking shale points to predict pore pressure.
Analysis of Wellbore Breakouts and Determination of Horizontal Stress Direction from Four Arm Calipers – A Study from Gulf of Kutch, Western Offshore Basin
11th Biennial International Conference & Exposition, Paper ID –37, SPG Jaipur, India, Dec 4-6, 2015
Abstract
Wellbore instability costs includes billions of dollar per year worldwide because of down hole drilling problems and majority of problems occurring are related to mechanical instability of wellbore. When the stresses exceed the limit of rock strength it fails and if failure is too severe drilling problems occur. It is nearly impossible to drill perfectly gauge hole without any wellbore breakouts, but our aim should be to avoid catastrophic failure and to keep the borehole in the ambit of modest intensity of breakouts and successfully drill the well with limited complications. Each drilled well provides tremendous amount of information about stresses around wellbore. If subsurface Geological and Geophysical data is studied clinically, prevention of catastrophic wellbore failure can be ensured. Breakout data analysis of drilled wells is an important tool in understanding present-day stress conditions in areas where more detailed stress measurements are not available. An understanding of in situ stress conditions is essential to evaluate the potential for slip on existing faults. In petroleum industry, knowledge of borehole stress conditions can be critical in placement of platform and well profile as well as hydraulic-fracturing treatments. The direction of horizontal stresses can be determined with the help of four arm caliper by analyzing borehole ovalisation.
Uncertainty in Well Log Analyses and Petrophysical Interpretations
11th Biennial International Conference & Exposition, Paper ID –8, SPG India, Dec 4-6, 2015
Abstract
Petrophysical analysis plays an important role in a reservoir study as it provides primary input data for characterization of subsurface formations and evaluation of resources. Common petrophysical input data to a reservoir study include porosity, water saturation, permeability and mineral or rock volumes. These reservoir variables are typically not directly measured by well logging tools; instead, they are usually derived through multiple processes, including acquisition, processing, interpretation and calibration. As each of these steps involves uncertainty, the resultant petrophysical data will have uncertainty and limitations. Uncertainties from well log and petrophysical interpretations should be analyzed, quantified and explicitly communicated to the integration team in order to be accounted for in reservoir characterization and modeling.
