Formation Evaluation Using Advanced Pulsed Neutron Tools

2019 ◽  
Author(s):  
Abdulaziz Al-Qasim ◽  
Ilies Mostefai ◽  
Sunil Kokal ◽  
Abdulaziz AlKhateeb
Keyword(s):  
Formation Evaluation ◽  
Pulsed Neutron

Advances in Cased-Hole Formation Evaluation—The Access to Untapped Tight-Gas Resources in Mature Fields: A Case Study from the Dnieper-Donets Basin, Ukraine

2021 ◽  
Author(s):  
Rafael Zambrano ◽  
Yevhen Makar ◽  
Michael Sadivnyk ◽  
Andriy Butenko ◽  
Oleksandr Doroshenko ◽  
...  
Keyword(s):  
Matrix Effects ◽  
Gas Production ◽  
Volume Estimation ◽  
Advanced Technology ◽  
Donets Basin ◽  
Neutron Spectroscopy ◽  
Tight Gas ◽  
Formation Evaluation ◽  
Pulsed Neutron ◽  
Low Porosity

Abstract The Sakhalin Field is located in the Dnieper-Donets Basin, east of Ukraine, and has been producing 7.7 billion cubic meters of natural gas in place from carboniferous rocks since the 1980s. Notwithstanding, it is strongly believed that significant untapped resources remain in the field, specifically those classified as tight intervals. Advances in wireline logging technology have brought, besides better accuracy on measurements behind the casing, a new measurement called fast neutron cross-section (FNXS), which has proved to be sensitive enough to the volume of gas in low-porosity formations. This enabled a quantitative interpretation for a better understanding of where these additional resources may lie in the Sakhalin Field. The methodology is based on advanced pulsed neutron spectroscopy logs to assess the essential formation properties such as lithology, porosity, and gas saturation and reduce the evaluation uncertainty in potential tight gas intervals. The advanced technology combines measurements from multiple detectors that represent independent formation properties such as formation sigma, thermal neutron porosity, FNXS, and elemental fractions. To address the lithology, the tool measures directly the rock elements required to determine representative mineralogy and matrix properties, which in turn are used to compensate for the matrix effects and obtain a reliable porosity and gas volume estimation. The methodology was tested on the upper Visean productive zones (Mississippian epoch) characterized by its low porosity (<10 pu) and permeability (<10 mD). In the past, those intervals have been overlooked because of inconclusive petrophysical interpretation based on basic openhole logs and their low production in some areas of the field. The necessity to finding new reserves has motivated the re-evaluation of possible bypassed tight-gas intervals by logging of mature wells behind casing in different sectors of the field. Advanced pulsed neutron spectroscopy logging behind casing uniquely identifies reserves in tight-gas intervals where basic open-hole interpretations were ambiguous. The gas production obtained from the perforated intervals supports the formation evaluation parameters estimated from the standalone interpretation of the pulsed neutron data. This work describes in detail the application of the alternative methodology and interpretation workflow to evaluate the formation through the casing. A concrete example is presented to illustrate the effectiveness of this approach in the revealing and development of tight gas reservoirs in mature fields in the Dnieper-Donets Basin.

Slim Pulsed Neutron Spectroscopy Lands for the First Time in the Egyptian Western Desert to Provide a Complete Formation Evaluation – A Novel Case Study from Abu Sennan Field

2021 ◽  
Author(s):  
Hesham Saied ◽  
Emad Refaat ◽  
Hesham Mokhtar ◽  
Mohamed Farouk ◽  
Sadek Salim ◽  
...  
Keyword(s):  
Reservoir Characterization ◽  
High Accuracy ◽  
Wellbore Stability ◽  
Western Desert ◽  
Formation Evaluation ◽  
Reservoir Evaluation ◽  
Cement Integrity ◽  
Stability Issues ◽  
First Time ◽  
Pulsed Neutron

Abstract Wellbore stability issues associated with mechanical failure of the formations frequently present a challenging environment for running openhole logs. Alternatively, casedhole logs can be used to provide multiple physical properties of the formation to help in reservoir characterization. Generally, conventional casedhole measurements have limitations due to the effect of borehole fluids as well as cement integrity. Therefore, it can be challenging to complete an accurate full reservoir evaluation using conventional casedhole measurements. In a field example from the Western Desert, Egypt, a state-of-the-art advanced slim pulsed neutron technology was deployed for the first time to provide a comprehensive standalone formation evaluation without openhole data. When hydrocarbon exploration and development move into more challenging environments, deployment of fit-for-purpose technologies is required. The advanced slim pulsed neutron processing algorithms were used for recording capture and inelastic elemental spectroscopy for rock elemental concentrations, including total organic carbon, detailed mineralogy, and matrix properties, simultaneously with sigma and other neutron-based outputs. By integrating the independent pulsed neutron measurements that are borehole self-compensated, casedhole reservoir characterization is now feasible with high accuracy and precision where the conveyance of openhole logging is of high risk due to borehole conditions and wellbore stability issues. This case demonstrates the applicability of advanced slim pulsed neutron logging for comprehensive reservoir characterization in casedhole environments without any openhole data. It presents this innovative approach for the first time in the Egyptian Western Desert in a field with complex geological background, mixed lithology, and reservoir fluids types. The characterization paved the way to a new gas discovery in a complex clastic environment with a total net pay of 36m of gas condensate. Detailed mineralogy, reservoir porosity, fluid types identification, and hydrocarbon saturation were obtained with high accuracy behind the cased borehole independent of cement integrity and borehole fluid invasion. Leveraging this novel approach, the same methodology can be applied to old reservoirs with limited openhole data available to provide a robust formation evaluation that would aid in re-assessing brownfields. The advanced slim pulsed neutron spectroscopy establishes a paradigm shift in reservoir characterization for casedhole environments to provide a comprehensive formation evaluation and fluid saturation without any openhole input. The workflow can be implemented in various scenarios as a cost-effective solution for reservoir evaluation or reservoir management applications.

Open- and Cased- Hole Formation Evaluation Workflows Running Together for Reducing Uncertainties in Gas Reservoirs: An Acquisition Data and Evaluation Strategy in Dnieper-Donets Basin, Ukraine

2021 ◽  
Author(s):  
Rafael Zambrano ◽  
Michael Sadivnyk ◽  
Yevhen Makar ◽  
Chiara Cavalleri ◽  
David Rose
Keyword(s):  
Magnetic Resonance ◽  
Donets Basin ◽  
Neutron Spectroscopy ◽  
Petrophysical Properties ◽  
Hole Formation ◽  
Gas Reservoirs ◽  
Formation Evaluation ◽  
Open Hole ◽  
Pulsed Neutron ◽  
Evaluation Techniques

Abstract Formation evaluation using cased-hole logs is a primary option for re-evaluating old wells in brownfields or contingency logging in new wells. Its consistency with a robust open hole evaluation is vital for its future implementation in field development. This work describes detailed open- and cased- hole evaluation workflows integrating different advanced subsurface measurements and alternative interpretation techniques to reduce the uncertainties of deriving the main petrophysical properties across the conventional and tight gas reservoirs in the Dnieper-Donets basin. Since not all open-hole measurements can be recorded behind casing and some of the cased hole logs are not characterized for open hole conditions, it is not always possible to implement the same evaluation techniques for measurements done in open hole and cased hole. Nevertheless, different measurements provide different formation responses that supplement their gaps from one another. A wireline data acquisition strategy has been elaborated to carry out formation evaluation workflows using open- and cased-hole data independently but learning from each other. The methodology is based on novel and non-standard evaluation techniques that use measurements from advanced wireline technology such as nuclear magnetic resonance (NMR) and advanced pulsed neutron spectroscopy logs. The methodology was applied to log data recorded on the Visean and Serpukhovian (Lower Carboniferous) productive gas zones, characterized by porosity (5-15pu) and permeability (0.1-100mD). The principal challenge for the formation evaluation of these reservoirs is deriving an accurate estimation of porosity, which requires removing the gas and matrix effects on the log responses. An inaccurate porosity estimation will result in an inaccurate permeability and water saturation, and the problem worsens in low-porosity rocks. In the open hole, the porosity computation from the Density-Magnetic Resonance (DMR) technique has proven to be more accurate in comparison with common single porosity methods. The same problem is addressed in cased hole conditions with the advanced pulsed neutron spectroscopy logs and a novel technique that combines the thermal neutron elastic scattering and fast neutron cross sections to obtain a gas-free and matrix-corrected porosity, as well as a resistivity independent gas saturation. The consistency of petrophysical properties independently estimated from the two separate workflows add confidence to the approach, and this is reflected in the gas production obtained from the perforated intervals. This script describes in detail the open- and cased- hole formation evaluation workflows and the wireline technology and methodologies applied. Actual examples illustrate the effectiveness of these quantitative approaches in the Dnieper-Donets basin.

Cased-hole interpretation workflow for determining residual oil saturation for mature fields

2015 ◽  
Vol 3 (1) ◽  
pp. SA135-SA142
Author(s):  
Venkataraman Jambunathan ◽  
FNU Suparman ◽  
Zhipeng Liu ◽  
Weijun Guo ◽  
Daniel Dorffer
Keyword(s):  
Best Practice ◽  
High Energy ◽  
High Count ◽  
Oil Saturation ◽  
Formation Evaluation ◽  
Well Completion ◽  
West Texas ◽  
Open Hole ◽  
Effective Use ◽  
Pulsed Neutron

Formation evaluation for mature oil fields remains a challenge for operators. Rock-petrophysical properties present large uncertainties following years of production. Formation evaluation becomes even more challenging when there is a lack of open-hole logging data as is typically the case. Logging programs for cased-hole formation evaluation are limited by the size of the well completion. In addition, a metallic casing often prevents the effective use of electric measurements. However, pulsed-neutron tools (PNTs) are a viable option for mature fields. We developed a brief review of PNT theory. The high-energy neutrons output at a high count rate fit the need of cased-hole applications. Application of pulsed-neutron technology for mature fields and a case history from west Texas, in which pulsed neutron technology was used to determine remaining oil saturation are discussed. We documented the best practice for data acquisition and the processing workflow. Having a good collaboration between operator and service provider helps to better understand the logging objectives and in job planning, which is important for the success of the logging operation.

Formation Evaluation Workflow Assesses Mass-Transport Complex Reservoirs

2021 ◽  
Vol 73 (02) ◽  
pp. 63-64
Author(s):  
Chris Carpenter
Keyword(s):  
Mass Transport ◽  
Natural Fracture ◽  
Total Carbon ◽  
Nuclear Spectroscopy ◽  
Matrix Analysis ◽  
Abu Dhabi ◽  
Fast Neutrons ◽  
Formation Evaluation ◽  
Transport Complex ◽  
Pulsed Neutron

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 203016, “Formation Evaluation in Mass-Transport Complex Reservoirs,” by Ulises Bustos, Schlumberger; Carlos Duran, Petróleos Sudamericanos; and Alvaro Chapellin, Schlumberger, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually from 9-12 November. The paper has not been peer reviewed. Mass-transport deposits (MTDs) are sedimentary, stratigraphic successions remobilized after initial deposition but before substantial lithification and transported downslope by gravitational processes as non-Newtonian rheological units. In the complete paper, the authors present an openhole advanced formation-evaluation approach that enables assessment of tight-matrix and natural-fracture systems at a level not previously accomplished in these types of geological formations. Introduction The considered wildcat project by Petroleos Sudamericanos is in the Lower Magdalena Valley hydrocarbon province in Colombia. From a stratigraphic point of view, the targets belong to tertiary deposits from the lower Neogene. Gravity-driven processes are complex and include creep, slide, slump, debris flow, and multiphase granular flows. The remobilized sedimentary deposits resulting from these processes are called MTDs or mass-transport complexes (MTCs) and are the main target job. Overlaying a crystalline basement, four MTC cycles were identified (although the present work only covers three MTC cycles) deposited in shallow marine environments. Each cycle consists of quartzite; phyllite; and schistose metamorphic rocks, largely gneiss with strong milonitization effects and foliated tremolitic marble in the top of the sequence. A summary of these types of rock is provided in the complete paper. The non-Archie nature of these rocks represents a challenge for formation evaluation. For reducing these uncertainties, a volumetric model with spectros copy dry-weight elements and nuclears was created that enabled solution of the total porosity, which was then benchmarked against the lithology-independent total nuclear magnetic resonance (NMR) porosity. The saturation computation was achieved with the fast neutron cross section method (FNXS) for the gas component and with total carbon for the liquid hydrocarbon fraction. The natural fracture system was analyzed with borehole image logs and with radial sonic-based dispersion analysis. The integration of matrix and natural-fracture assessment provided a robust formation evaluation that enabled identification of the main interest zones across the MTC cycles. Multifunction Spectroscopy for Matrix Analysis The multifunction spectroscopy tool is 1.72 in. in diameter and 18.3 ft long, consisting of a pulsed neutron generator and four detectors. The first detector is the compact neutron monitor, sensitive to fast neutrons and located adjacent to the high-output pulsed neutron source, measuring neutron output with high accuracy and precision. The second (near) and third (far) gamma-ray detectors are used for inelastic and capture spectroscopy measurements. The fourth and farthest-spaced detector (deep) uses an yttrium aluminum perovskite scintillator, which is involved in gas detection and assessment. The nuclear spectroscopy measurement is performed in energy and time domains; both aspects are described in detail in the complete paper.

Local atomic structure of relaxor ferroelectric solids studied by pulsed neutron scattering

1994 ◽  
Vol 52 ◽  
pp. 554-555
Author(s):  
T. Egami ◽  
H. D. Rosenfeld ◽  
S. Teslic
Keyword(s):  
Neutron Scattering ◽  
Atomic Structure ◽  
Argonne National Laboratory ◽  
Relaxor Ferroelectrics ◽  
Relaxor Ferroelectric ◽  
Crystallographic Structure ◽  
Chemical Inhomogeneity ◽  
Distribution Analysis ◽  
Ferroelectric Transition ◽  
Pulsed Neutron

Relaxor ferroelectrics, such as Pb(Mg1/3Nb2/3)O3 (PMN) or (Pb·88La ·12)(Zr·65Ti·35)O3 (PLZT), show diffuse ferroelectric transition which depends upon frequency of the a.c. field. In spite of their wide use in various applications details of their atomic structure and the mechanism of relaxor ferroelectric transition are not sufficiently understood. While their crystallographic structure is cubic perovskite, ABO3, their thermal factors (apparent amplitude of thermal vibration) is quite large, suggesting local displacive disorder due to heterovalent ion mixing. Electron microscopy suggests nano-scale structural as well as chemical inhomogeneity.We have studied the atomic structure of these solids by pulsed neutron scattering using the atomic pair-distribution analysis. The measurements were made at the Intense Pulsed Neutron Source (IPNS) of Argonne National Laboratory. Pulsed neutrons are produced by a pulsed proton beam accelerated to 750 MeV hitting a uranium target at a rate of 30 Hz. Even after moderation by a liquid methane moderator high flux of epithermal neutrons with energies ranging up to few eV’s remain.

Data Acquistion and Formation Evaluation Strategies in Anistrospic, Tight Gas Reservoirs

2008 ◽  
Author(s):  
Hans de Koningh ◽  
Bernd Heinrich Herold ◽  
Koksal Cig ◽  
Fahd Ali ◽  
Sultan Mahruqy ◽  
...  
Keyword(s):  
Tight Gas ◽  
Gas Reservoirs ◽  
Tight Gas Reservoirs ◽  
Formation Evaluation ◽  
Evaluation Strategies ◽  
Data Acquistion
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