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Abstract During the 2014 SPWLA Topical Meeting on “Educating the Petrophysicist”, it recommended that “A minimum set of standards in terms of both knowledge and skills (competencies) for an entry level petrophysicist (SPWLA, 2014). Similar proposal has been raised before as well (Loermans, 2002). With the rapid advance in technology, continuous crew change, and a natural pandemic affecting the oil and gas industry, the learning pattern has been changing from traditional in-person structured courses to more online, on-demand, short course training. For those interested in entering petrophysics discipline or furthering their petrophysics knowledge and skills, the learning path is less clear than other discipline like reservoir engineering, or geology, due to the lack of university degree program in Petrophysics. SPWLA Education SIG has taken on this challenge and developed skill set guidelines for petrophysicists as independent contributors. The current version of the guidelines covers topics including: General Geoscience and Engineering Operations, Fundamental Petrophysical Data Acquisition, Integrated Formation Evaluation, LWD Petrophysics in Formation Evaluation and Geosteering, Reservoir Dynamic Surveillance, Integrated Petrophysical Modeling, and Data Driven Petrophysics. In each topic, it includes basic skills as well as specialized skills. The document was developed with oil and gas industry in mind and can be adapted for petrophysicists working in related fields such as geothermal, mining, carbon management, water resources evaluation, etc. The document will be useful for students interested in learning to be a petrophysicist, a company interested in developing a training program for petrophysicists, and an organization interested in developing skill assessment program for petrophysicists.
Abstract This is a review paper on applying Magnetic Resonance Imaging Logging (MRIL) methods for detecting and quantitatively measuring volumes occupied by brine, gas, and oil. These methods include Differential Spectrum Method (DSM), Enhanced Diffusion Method (EDM), Shift Spectrum Method (SSM) in transverse relaxation time (T2) domain or in spin-echo time domain (i.e., Time Domain Analysis; TDA), Total Porosity Measurement (TPM), and Injecting Contrast Agent Method (ICAM). The principles, data acquisitions, and data processes of these methods and their applications are introduced and discussed. P. 593
Wireline logging operations often require real time interactions during the operations. The logging engineer along with the organization's technical support backbone provide technical knowledge of tool physics and operations while petrophysicists, G&G specialists, and well engineers of the operating company experts have intimate knowledge of the formations, the reservoirs, and the well environments. Technology development has been an integral part of wireline logging as downhole tools have evolved to incorporate new measurements and novel ways of acquiring and processing data, but it still largely relies on standard crews of one of more field engineers and a handful of operators. This model has remained the same for decades in contrast to technology already been deployed in drilling for instance, where a fully closed loop directional drilling system has automated the trajectory drilling service. This paper describes a remote wireline logging solution that enables downhole wireline logging tools to be remotely controlled. The solution optimizes data transmission in order to minimize the bandwidth required for data duplication. It also automates tasks that would otherwise be manual, laborious, or time-consuming. The benefits of real time collaboration are many and include providing live technical support, improving knowledge sharing and collaboration, providing a relevant training environment to less experienced staff, as well as lowering operational costs and optimizing crew size and people on site - two particularly important drivers in a post-Covid-19 world. The combination of the current depressed economic environment, the cyclic nature of the oil and gas industry, and its skewed demographics will aggravate the irreversible loss of experience and corporate knowledge that has been at work for years-in operators and service companies alike so knowledge management solutions leveraging real time monitoring and control are called for - now more than ever before.
ABSTRACT In mature multilayered gas reservoirs, a common problem is determining whether unperforated potential gas zones behind casing that were identified on openhole logs are still at original reservoir pressure or have been depleted over time via offset well production. If the unperforated zones are still near original reservoir pressure, a workover targeting the zone can be justified to maintain well production as existing production declines. If the unperforated zones are depleted, a workover will not be economical. One way to solve this problem is by running a cased hole pulsed neutron log that can make three independent formation measurements of sigma, porosity (TPHI), and fast neutron cross section (FNXS) in the well and using an interpretation workflow to estimate the current gas pressure. The workflow consists of selecting an appropriate equation of state for the gas, assuming a chemical composition of the gas, determining the pulsed neutron measurement variation versus pressure for the gas, and forming an equation solving for pressure where all other variables in the measurement response equation are assumed to be known, including water saturation. Information can be integrated from openhole logs such as porosity, lithology, and water saturation. Performing the workflow for the three independent measurements gives three estimates of gas pressure, which brings confidence to the interpretation if they are consistent. A case history from the Gulf of Mexico is presented. A potential gas zone in a producing well behind casing was considered for a workover and was evaluated with the interpretation workflow. Three gas pressures were computed based on the cased hole pulsed neutron measurements and formation evaluation from previous openhole logs. All indicated a current pressure near the original reservoir pressure. A workover was performed, and the well was successfully produced with the measured gas pressure consistent with the pressures predicted from the interpretation workflow. The well is economically producing, justifying the workover costs and demonstrating the usefulness of this workflow.
Abstract The Alta field in the Barents Sea was discovered in 2014. The reservoir formation is primarily carbonate rocks with high formation water salinity. Extensive waterflooding processes have led to an approximately 200-m rise of water level. The complexities and uncertainties regarding imbibition, current free water level, and pseudo fluid contacts within the field translate into uncertainty in the hydrocarbon volume estimation. Initial, triple-combo-based petrophysical evaluations have already been updated using advanced log measurements, as reported in an earlier publication. The evaluation is now consolidated by using two new techniques relying on advanced spectroscopy logging and combination with dielectric dispersion logging. Their objective is to further reduce the uncertainty in water saturation associated with variable apparent water salinity. The present contribution proposes a workflow that relies on two novel techniques. The first technique is a direct quantitative measurement of formation chlorine concentration from nuclear spectroscopy, which helps resolve the formation's apparent water salinity and provides a way to calibrate formation matrix sigma. The second technique relies on the existing combined inversion of dielectric dispersion and formation sigma, including explicitly invasion effects. This second technique benefits from the first technique's insight to adjust sigma interpretation and provide bounds for possible salinity variations. The workflow provides robust flushed and unflushed zone salinities, here the most uncertain and variable parameter, combined with accurate estimations of virgin and residual hydrocarbon saturations. The quantification of dielectric textural parameters describing how the water is shaped inside the formation is also improved, contributing to the improvement of virgin zone hydrocarbon saturation estimation.