In making the petrophysical calculations of lithology, net pay, porosity, water saturation, and permeability at the reservoir level, the development of a complete petrophysical database is the critical first step. This section describes the requirements for creating such a database before making any of these calculations. The topic is divided into four parts: inventory of existing petrophysical data; evaluation of the quality of existing data; conditioning the data for reservoir parameter calculations; and acquisition of additional petrophysical data, where needed. The overall goal of developing the petrophysical database is to use as much valid data as possible to develop the best standard from which to make the calculations of the petrophysical parameters. The second step in working with the petrophysical data is to evaluate the quality of each of these types of data. This step requires that the data inventory and database preparation steps are completed first so that this second step can occur as a systematic and complete process. The evaluation process is a "compare and contrast" exercise. The evaluation of log-data quality has many aspects. This should be noted in the petrophysical database. "Flags" of various types should be stored, for example, to denote intervals where the hole size exceeds some limit, or where there is cycle-skipping on the sonic logs. Logging tools sometimes become temporarily stuck as a log is being run. When the tool is stationary, each detector on it becomes stuck at a different depth, so the interval of "stuck" log will vary for each log curve. For example, the neutron log typically sticks over an interval approximately 10 ft above the stuck interval on a density log. It may be possible to "splice" in a replacement section of log from a repeated log section, or the invalid readings may simply be deleted. Second, each log is formally calibrated before the start of each logging run by various calibration standards. The logs are also checked again after the run. Calibration records may assist in determining the quality of the logs. Perhaps of equal importance are the written comments on the log heading made immediately after the job by the logging engineer. Third, systematic influences on the quality of log readings should be corrected. For example, if some of the wells are drilled with water-based mud (WBM), the effect of WBM-filtrate invasion on various resistivity logs can be quantified. This is done by computations made using the various resistivity logs in the same wellbore; however, where deep invasion of WBM filtrate occurs, offsetting wells drilled with oil-based mud (OBM) give a good comparison. The induction logs in OBM wells can provide accurate true reservoir resistivity values in thick hydrocarbon zones. See the chapter on resistivity and SP logging in this volume of the Handbook for more information on how invasion effects can be handled. Boreholes are not always right cylinders.
Water saturation (Sw) determination is the most challenging of petrophysical calculations and is used to quantify its more important complement, the hydrocarbon saturation (1 – Sw). Complexities arise because there are a number of independent approaches that can be used to calculate Sw. The complication is that often, if not typically, these different approaches lead to somewhat different Sw values that may equate to considerable differences in the original oil in place (OOIP) or original gas in place (OGIP) volumes. The challenge to the technical team is to resolve and to understand the differences among the Sw values obtained using the different procedures, and to arrive at the best calculation of Sw and its distribution throughout the reservoir vertically and areally. A 10% pore volume (PV) change in Sw has the same impact as a 2% bulk volume (BV) change in porosity (in a 20% BV porosity reservoir). This listing is the chronological order in which data are likely to become available, not in a ranked order based on the accuracy of the various methods. The choice of which Sw-calculation approach to use is often controlled by the availability of the various types of data. If no OBM cores have been cut, then this technique cannot be used unless funds are spent to acquire such data from one or more newly drilled wells. This is not a high incremental cost when OBM use is planned for other purposes. Resistivity logs are run in all wells, so these data are available for making standard-log-analysis Sw calculations. A key consideration when making calibrated Sw calculations is the availability of special-core-analysis (SCAL) data on core samples from the particular reservoir; that is, the number of laboratory electrical-property and Pc/Sw core-plug measurements that have been made. The technique chosen to calculate Sw is often a hybrid that combines the use of two of these basic data sources. For example, the OBM-core Sw data can be used in combination with the resistivity logs to expand the data set used to include all wells and the whole of the hydrocarbon column. Alternatively, the OBM-core Sw data can be used in combination with the Pc/Sw data. In this way, the OBM-core Sw data define the S w values for the majority of the reservoir, whereas the Pc/Sw data define the Sw values in the interval just above the fluid contact and perhaps in areas of the field where Pc data are available but OBM-core data are not. This section discussed the input-data availability and data quality issues for each Sw technique.
Total is determined to push ahead with its plans to drill for oil in the Amazon basin, it said on 1 June as Greenpeace activists interrupted its annual general meeting in protest over the project. An audit of the Martin Linge project was conducted by the Petroleum Safety Authority Norway (PSA) on 28–30 March 2017. This was directed at technical safety, electrical equipment, maintenance management, and Total’s own follow-up of technical barriers during the commissioning phase.
Total is determined to push ahead with its plans to drill for oil in the Amazon basin, it said on 1 June as Greenpeace activists interrupted its annual general meeting in protest over the project. This paper provides a broad overview of the Great Amazon Reef System based on the first-ever video surveys of the region.
Well RXY is located in Cairn’s Ravva offshore field in the Krishna-Godavari Basin in India. One goal for the field was significant crude production by means of a secondary reservoir section. This paper presents technologies and best practices to improve oil recovery in mature fields through waterflooding optimization. These technologies have proved practical and cost-effective. Three onshore fields in the Emirate of Sharjah, United Arab Emirates, have more than 30 years of production history from more than 50 gas-condensate wells.
Decommissioning and abandonment comes with its share of unexpected surprises, but many of those surprises could be avoided merely through better planning and care. The next big wave of decommissioning and abandonment projects is set to occur in the Asia-Pacific region, and APAC’s operators are now tasked with finding cost- and time-effective ways of unwinding their huge agglomeration of wells and facilities. The outlook in the UK is a case study of the squeeze facing E&P in other basins where operators are trying to pay to sustain production with discoveries, while plugging and abandoning old wells, all paid for by the lean cash flow due to low oil prices. An influx of new investment and operational efficiencies borne out of the oil price downturn have led to a drop in projected decommissioning costs. Decommissioning multiple wells in one campaign helped some operators achieve time savings of 33% per well.
Ghawar vs. Permian Basin: Is There Even a Comparison? While some try to put the two enormous oil producers toe-to-toe, the best thing to do might be to understand why they are different. A challenging problem of automated history-matching work flows is ensuring that, after applying updates to previous models, the resulting history-matched models remain consistent geologically. Production growth in the Permian Basin requires drill rigs running at a high pace. That is challenging companies to push well productivity.
America’s hottest oil patch is producing so much natural gas that, by the end of last year, producers were burning off more than enough of the fuel to meet residential demand across the whole of Texas. Equinor has agreed to align its business model with the goals of the 2015 Paris climate accord and will review its corporate lobbying policy and the carbon intensity of its products, the company said. It will also link executive pay to climate-related targets. A wave of satellites set to orbit the Earth will be able to pinpoint producers of greenhouse gases, right down to an individual leak at an oil rig. Scientists from the University of East Anglia have discovered a unique oil-eating bacteria in the deepest part of the Earth’s oceans—the Mariana Trench. A bipartisan group of senators introduced a bill to increase federal funding toward developing carbon capture technology while also committing to fossil fuel use. Oilfield wastewater disposal volumes are expected to double in the Permian Basin within the next 2 to 3 years, a new analysis from global energy intelligence firm Wood Mackenzie shows.
Models were developed for these wells for future water-production prediction and a spatial analysis was also conducted. This study summarizes hydrate-inhibition practices for these sea lines, and indicates a possibility of using them as indirect thermometers to provide important physical oceanographic data. Results of the experimental and numerical heat-transfer analysis conducted on a T-shaped acrylic-glass pipe, representing a production header in a subsea production system with a vertical deadleg. The Hail 3D transition-zone seismic survey carried out by ADNOC is located in a UNESCO world-biosphere reserve. Effective environmental and ecological management throughout the project was attained through working procedures and monitoring programs. The understanding of solid-particle flow regimes in pipelines for any operational conditions is important for identifying the nature of particle interaction and movement. In this paper, a comprehensive analysis of solid-particle flow regimes in stratified flow in a horizontal pipeline is presented. High-concentration polymer flooding can improve oil-displacement efficiency but separation of oil/water mixture becomes more difficult because of emulsification.
Africa (Sub-Sahara) Vaalco Energy started oil production from the Etame 12-H development well offshore Gabon. The well was drilled to a measured depth of approximately 3450 m and was targeting the recently discovered lower lobe of the Gamba reservoir. It was brought on line at a rate of 2,000 BOPD with no indication of hydrogen sulfide. Vaalco (28.07%) is the operator with partners Addax Petroleum (31.63%), Sasol (27.75%), Asia Pacific KrisEnergy started drilling the Rossukon-2 exploration well on Block G6/48 in the Gulf of Thailand, using the Key Gibraltar jackup rig. The well will reach a total depth at 5,462 ft and will test Early Miocene stacked fluvial sandstones on a broad structural high.