Copyright 2019 held jointly by the Society of Petrophysicists and Well Log Analysts (SPWLA) and the submitting authors. ABSTRACT Today, many machine learning techniques are regularly employed in petrophysical modelling such as cluster analysis, neural networks, fuzzy logic, self-organising maps, genetic algorithm, principal component analysis etc. While each of these methods has its strengths and weaknesses, one of the challenges to most of the existing techniques is how to best handle the variety of dynamic ranges present in petrophysical input data. Mixing input data with logarithmic variation (such as resistivity) and linear variation (such as gamma ray) while effectively balancing the weight of each variable can be particularly difficult to manage. DTA is conceived based on extensive research conducted in the field of CFD (Computational Fluid Dynamics). This paper is focused on the application of DTA to petrophysics and its fundamental distinction from various other statistical methods adopted in the industry. Case studies are shown, predicting porosity and permeability for a variety of scenarios using the DTA method and other techniques. The results from the various methods are compared, and the robustness of DTA is illustrated. The example datasets are drawn from public databases within the Norwegian and Dutch sectors of the North Sea, and Western Australia, some of which have a rich set of input data including logs, core, and reservoir characterisation from which to build a model, while others have relatively sparse data available allowing for an analysis of the effectiveness of the method when both rich and poor training data are available. The paper concludes with recommendations on the best way to use DTA in real-time to predict porosity and permeability. INTRODUCTION The seismic shift in the data analytics landscape after the Macondo disaster has produced intensive focus on the accuracy and precision of prediction of pore pressure and petrophysical parameters.
Understanding petrophysical properties well enough to make drilling decisions, particularly for tight gas can be a challenge. A new computer system aims to help analyze the extensive data involved. There are more than 100 accumulations in the southern North Sea that are flagged as stranded fields. One of these stranded tight gas fields, the Kew field, has been developed successfully with the use of a subsea well, horizontal drilling, and hydraulic fracturing.
With the purchase, the growing, privately-held Chrysaor Holdings will expand its UK North Sea production to 185,000 BOE/D. The state-run offshore company has found a gas and condensate field that holds an estimated 250 million BOE. The latest example of the offshore sector's march toward automated wellbore construction will take shape later this year in the North Sea. Just 2 months after issuing more than a hundred licenses, the Oil and Gas Authority begins the process again for a whole new set of blocks. The company announced it would “initiate the process” of marketing its UK Central North Sea fields as part of a portfolio review.
This course will discuss the practical state-of-the-art techniques of Volume to Value (VV) to help attendees assess exploratory deepwater offshore oil and gas prospects and quantify economic values of the prospects. Attendees will learn how to develop a preliminary field development plan for a given discovery prospect and estimate oil and gas recovery, wells required, and costs. They will also learn how to conduct economic evaluation for lease sales or farm-in opportunities. Upon completion of this course, attendees should be able to evaluate the commercial potential of original oil and gas in-place in exploratory blocks and develop preliminary field development plans. Attendees should also be able to obtain value of the opportunity in order to make the decision to go ahead and develop the field or walk away from it, as well as identify constraints in terms of geology and engineering that will make it viable or impede the realization of the project.
With a shallow water flow-back in excess of 200 bbl/hr from the Top Chalk formation during the 17½" section, the deviated exploration / development well "Well #4" was planned and drilled successfully with a jackup rig. The well was planned from a platform in the Southern North Sea.
The primary goal for the 17½" section was to safely drill to section TD, set casing and cement same with zero incident in a minimum amount of time while encountering shallow water flow.
The key challenges for this well were: Flowing Top Chalk Formation: The Top chalk formation flowed at all three previously drilled offset wells with 12.0 ppg EMW and approximately 200 bbl/hr. Several attempts to shut in the well and stop the flowing Top Chalk on the offset well "Well #1" failed. Obtaining regulatory approval from authorities, and commitment and acceptance by all involved parties to drill the well under flowing conditions. Hole cleaning and hole stability considerations when drilling with seawater Permanently shutting off the shallow water flow with a two-stage cementation. Rig uncertainty and general service market (in 2017): A new drilling contractor and drilling services not familiar with the peculiarities of operations in this area Safety, communication and human factor considerations for a potentially hazardous non-routine operation.
Flowing Top Chalk Formation: The Top chalk formation flowed at all three previously drilled offset wells with 12.0 ppg EMW and approximately 200 bbl/hr. Several attempts to shut in the well and stop the flowing Top Chalk on the offset well "Well #1" failed.
Obtaining regulatory approval from authorities, and commitment and acceptance by all involved parties to drill the well under flowing conditions.
Hole cleaning and hole stability considerations when drilling with seawater
Permanently shutting off the shallow water flow with a two-stage cementation.
Rig uncertainty and general service market (in 2017): A new drilling contractor and drilling services not familiar with the peculiarities of operations in this area
Safety, communication and human factor considerations for a potentially hazardous non-routine operation.
A collaborative well-planning and preparation process involving the operator drilling team, the drilling contractor and key service providers was critical to the success of the overall operation.
The team worked together to ensure all requirements, risk mitigating measures, lessons learned from previous operations and offset wells, and human factor considerations were incorporated in the execution program.
The well was successfully drilled to TD, evaluated, completed and flowed. The notable highlights from the top-hole drilling operation include: Fastest 17-1/2" phase compared to offset wells: drilling and casing operations completed in 94.25 hrs with the well flowing. Zero NPT in the 17-1/2" drilling phase: drilled 654 m in 37.5 hrs with an average ROP of 17.5 m/hr without any complications. Continuous monitoring and fingerprinting of the shallow water flow
Fastest 17-1/2" phase compared to offset wells: drilling and casing operations completed in 94.25 hrs with the well flowing.
Zero NPT in the 17-1/2" drilling phase: drilled 654 m in 37.5 hrs with an average ROP of 17.5 m/hr without any complications.
Continuous monitoring and fingerprinting of the shallow water flow
This paper describes the key planning considerations, preparations and creative solutions deployed to deliver the well. The lessons learnt will serve as a resource for planning future wells with similar challenges.
The IADC and SPE are committed to delivering a balanced agenda around Diversity and Inclusion, to support member companies as they strive to address the gap in the Oil & Gas Sector. In 2019 the SPE/IADC International Drilling Conference and Exhibition in The Hague will host a session that allows delegates to explore the challenges facing the industry and hear firsthand, how it can be addressed. This initiative aims to build on the efforts already being undertaken at individual company levels to attract, develop and retain female staff - especially in technical and senior management roles, and to remove barriers that may currently hinder or discourage women from rising through the ranks into leadership roles. The aim is to address the factors contributing to the gender gap and to advantage all companies, their owners and shareholders through the incremental performance and value that parity will generate. This is good for our people, good for our stakeholders, and good for our business. Whilst in 2017 the session focused on subjects arising from DAVOS 2016 namely Leadership, Aspiration, goal setting, STEM, recruitment and retention, corporate culture and work life balance, the panel now feel it is time to move the conversation forward with some hard-hitting topics that affect the lives of many. Make sure you join us for this special session in The Hague.
The democratization of artificial intelligence began with the collection of large datasets and the ability to consume them for inferences and prediction by leveraging exponentially increasing computational power. This was further enhanced by the ability to parallel process datasets by breaking them up into independent units and applying fast computation to those units using Graphical Processing Units (GPUs). We discuss one such application in the area of seismic interpretation in the oil and gas sector. Seismic interpretation is particularly suitable since seismic datasets’ characteristics make them inherently amenable to parallel processing in post-stack format.
True big data in the oil and gas sector exists in the seismic arena, where up to one terabyte of data or more can be collected per hour. We show that while preprocessing is required for cleansing and quality checking the data, novel techniques can be applied from the medical and healthcare sectors, namely radiology, for image processing and anomaly detection in images. Further, we also show methods of preprocessing the seismic data, development of seismic images, and novel denoising techniques that lead to the construction of seismic cubes.
3D and 4D seismic cubes post-stack are today amenable to a plethora of neural network based parallel processing methods for anomaly detections. Using such techniques, the achievable speeds to detect anomalies are effectively above ten times what an experienced human being can do. These methods, at their very best, go far beyond human capabilities in terms of processing terabytes to petabytes of data. Such image processing is in use in image recognition, for example, in border control for person identification and verification, and satellite image analysis to discover the minutest of details. We showcase novel techniques based on Convolutional Neural Networks and Deep Neural Networks being utilized for subsurface geological and geophysical properties identification. Further developments of our current and future work are also discussed.
Our presentation specifically describes methods based on Convolutional and Deep Neural Networks to predict faults and salt domes in seismic images. The ability of Deep Neural Networks to continuously learn and self-optimize is the basis of our novel approach. A common criticism of machine learning methods is that most reported results describe results on field data where part of the field data has been used in training the neural network algorithms being used. In the work reported here, we describe the results of our algorithm on two completely blind field data sets – where none of the field data has been used in training the algorithms.
The objective of this paper is to outline the issues that should be considered and provide guidance on the assessment of reserves and resources in a variety of scenarios where petroleum accumulations straddle licence boundaries.
Petroleum accumulations straddling boundaries are common. Global estimates of the numbers of fields which straddle boundaries vary but run into hundreds or thousands with several countries/basins reported to have up to half of discovered fields straddling at least one boundary.
It is widely recognised that development of oil and gas fields straddling boundaries can be optimised through unitisation. However, less attention has been paid to the assessment of reserves and resources in such situations and how the nature and status of unitisation, or lack thereof, impacts reserves and resources assessment using the Petroleum Resources Management System (PRMS). Even in ideal situations where unitisation has been agreed, the methods and objectives of unitisation and reserves assessment are quite different. Unitisation is typically: based on in-place volumes, considers a single deterministic interpretation, follows specified technical procedures, without consideration of economics and is done at a specified time during a field's life, and may be followed by subsequent redeterminations. Reserves are: remaining recoverable volumes, consider a range of outcomes, do not follow specific procedures, do consider economics and are typically assessed at regular intervals, often annually, throughout a field's life.
The paper will examine a range of scenarios from those where unitisation has been agreed, through those where unitisation is mandated but not yet in place, to those where no unitisation is either in place or mandated. Several factors influence how such situations should be assessed. The status of the field and data on either side of the boundary will be considered including: have wells been drilled on one or both sides? Is production occurring on one or both sides? What consideration should reserves assessors give to scheduled redeterminations where agreements, formulas and outcomes are unknown. There are many cases where production has occurred on both sides and unitisation is required retroactively. Regulatory requirements regarding unitisation vary throughout the world. Where present, regulations often require unitisation to occur, but the practice lags behind the legislation. There are also situations where production has occurred on one or both sides in "rule of capture" scenarios without any requirement or plan for unitisation. Accumulations straddling international boundaries introduce additional factors that should be considered.