MULTIDETECTOR PULSED NEUTRON TOOL APPLICATION IN LOW POROSITY RESERVOIR – A CASE STUDY IN MUTIARA FIELD, INDONESIA

2020 ◽  
Author(s):  
Aditya Arie Wijaya ◽  
◽  
Rama Aulianagara ◽  
Weijun Guo ◽  
Fetty Maria Naibaho ◽  
...  
Keyword(s):  
Pulsed Neutron ◽  
Low Porosity

A Pulsed Neutron Comparison Between an Open and Casedhole Well: An Alaskan Case Study

2018 ◽  
Author(s):  
J. Burt ◽  
T. Zhou ◽  
D. A. Rose ◽  
R. Grover ◽  
S. Ahmad ◽  
...  
Keyword(s):  
Pulsed Neutron

Logging Optimization and Data Analysis Enabling Bypass Pay Identification and Hydrocarbon Quantification with Advanced Pulsed Neutron Behind Casing

2021 ◽  
Author(s):  
Sviatoslav Iuras ◽  
Samira Ahmad ◽  
Chiara Cavalleri ◽  
Yernur Akashev
Keyword(s):  
Cross Section ◽  
Pore Space ◽  
High Energy ◽  
Elastic Cross Section ◽  
Gas Production ◽  
Donets Basin ◽  
Lithology Identification ◽  
Open Hole ◽  
Pulsed Neutron

Abstract Ukraine ranks the third largest gas reserves in Europe. Gas production is carried out mainly from the Dnieper-Donets Basin (DDB). A gradual decline in reserves is forcing Ukraine to actively search for possible sources to increase reserves by finding bypassed gas intervals in existing wells or exploration of new prospects. This paper describes 3 case studies, where advanced pulsed neutron logging technology has shown exceptional value in gas-bearing layer identification in different scenarios. The logging technology was applied for formation evaluation. The technology is based on the neutron interaction with the minerals and the fluids contained in the pore space. The logging tool combines measurements from multiple detectors and spacing for self-compensated neutron cross-capture section (sigma) and hydrogen index (HI), and the Fast Neutron Cross Section (FNXS) high-energy neutron elastic cross section rock property. Comprehensive capture and inelastic elemental spectroscopy are simultaneously recorded and processed to describe the elemental composition and the matrix properties, reducing the uncertainties related to drilling cuttings analysis, and overall, the petrophysical evaluation combined with other log outputs. The proposed methodology was tested in several wells, both in open hole and behind casing. In the study we present its application in three wells from different fields of the DDB. The log data acquisition and analysis were performed across several sandstone beds and carbonates formation with low porosities (<10%), in various combinations of casing and holes sizes. The results showed the robustness and effectiveness of using the advanced pulsed neutron logging (PNL) technologies in multiple cases: Case Study A: Enabling a standalone cased hole evaluation and highlighting new potential reservoir zones otherwise overlooked due to absence of open hole logs. Case Study B: Finding by-passed hydrocarbon intervals that were missed from log analysis based on conventional open hole logs for current field operator. Case Study C: Identifying gas saturated reservoirs and providing solid lithology identification that previously was questioned from drilling cuttings in an unconventional reservoir.

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.

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