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.

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.

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.

DETERMINATION OF RESIDUAL OIL SATURATION IN A WATER AND GAS FLOODED GIANT OIL RESERVOIR USING CORE, CONVENTIONAL AND PULSED NEUTRON LOGS

2021 ◽  
Author(s):  
Mike Davenport ◽  
◽  
Rufat Guliyev ◽  
Kasim Sadikoglu ◽  
Pavel Gramin ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Clay Content ◽  
Oil Field ◽  
Residual Oil ◽  
Oil Saturation ◽  
Residual Oil Saturation ◽  
Future Production ◽  
Open Hole ◽  
Pulsed Neutron

The understanding of residual saturation in an oil field in mid-development is essential for estimating the cumulative production achievable, optimizing the future production mechanisms planned for infill targets, development of adjacent reservoir levels and optimizing the design of future facilities. The ACG (Azeri, Chirag, Gunashli) field is a giant oil field located about 120 km offshore in the South Caspian Sea, Azerbaijan. The field consists of multiple stacked clastic reservoirs including the Fasila and Balakhany formations, each with variable oil water contacts, and variable presence and fill level of gas caps. The Fasila reservoirs have been nearly fully developed. Both down flank water injection and crestal gas injection have been employed to drive oil towards producers. These two processes result in different residual oil “trapping” mechanisms which have been explored by logging and coring. Future development of overlying reservoirs can be optimized if we understand the effectiveness of these mechanisms to improve oil recovery and understand produced fluid compositions to enable facilities optimization to handle them. Established techniques to measure the residual oil saturation in a live field depletion, such as conventional open hole logging, pulsed neutron logging and direct core measurements have been employed. This paper investigates the methodology of each technique and the comparison of the magnitude and uncertainty of the saturations obtained. The sands in the ACG main reservoirs are relatively massive and high Net-to-Gross (NTG), however their clay content and distribution is quite variable leading to a range of rock types which behave differently under fluid sweep, and the presence of both intra reservoir sealing shales and lateral sand quality variations lead to a complex pattern of sweep behavior. It was considered that conventional core would be the principle measurement, with the most direct estimation of downhole fluid conditions as well as achieving all other coring objectives. Core was acquired on two pilot wells, one behind the water flood front and another behind the expanding crestal gas cap. Several innovative core analysis techniques were employed. A full conventional log suite was acquired in both wells as well as an open hole pass of a multi detector pulsed neutron log in the crestal gas swept well. The analysis of all this data has led to some interesting conclusions. Previous core flood experiments had led the team to believe gas is more efficient than water in terms of lowering residual oil saturation and reaching higher recovery factors. The new core demonstrated that such low residual oil saturations are achieved more slowly than originally thought, though it didn't change the view of efficiency of gas displacement relative to water. It is also likely that reservoir heterogeneity has had a bigger impact on the variation in residual oil saturation between layers than reservoir quality itself.

Enhanced Productivity in Horizontal Open Hole Completion Using Integrated Dynamic Diversion Acid Squeeze Technique in Highly Depleted Well: Successful Application in West Kuwait Field

2021 ◽  
Author(s):  
Salem Al-Sabea ◽  
Abdullah Abu-Eida ◽  
Milan Patra ◽  
Yousef Haider ◽  
Hasan Al Qattan ◽  
...  
Keyword(s):  
Acid Treatment ◽  
Best Practice ◽  
Treatment Options ◽  
High Energy ◽  
Lessons Learned ◽  
High Potential ◽  
Fluid Loss ◽  
Selective Treatment ◽  
Field Development ◽  
Open Hole

Abstract The Minagish field in West Kuwait is a high potential field which poses several challenges in terms of hydrocarbon flow assurance through highly depleted tight carbonate intervals with uneven reservoir quality and curtailed mobility. These conditions have shifted the field development from vertical to horizontal wellbore completions. Achieving complete wellbore coverage is a challenge for any Matrix Acid treatment performed in a long openhole lateral with disparities in reservoir characteristics. The fluid will flow into the path of least resistance leaving large portions of the formation untreated. As a result, economic Acid treatment options dwindle significantly, thus reservoir stimulation results are not always optimum. A multistage acid stimulation technique using Integrated Dynamic Diversion (IDD) has been performed in a West Kuwait field well. The process uses active fluid energy to divert flow into a specific sweet point (high pressure point) in the lateral, which can pinpoint and precisely place acid treatment at the desired location. The process uses two self-directed fluid streams: one inside the pipe and one in the annulus. The process mixes the two fluids downhole with high energy to form a consistent controllable mixture. The technique includes pinpoint fluid jetting at the point of interest, followed by customized foamed HCL acid systems employed for improving individual stage targets in depleted reservoir. The IDD diversion shifts the acid treatment to unstimulated areas to create complex wormholes which increase reservoir contact volume and improve overall conductivity in the lateral. The kinetics and chemical diversion of the IDD methodology are highly critical to control fluid loss in depleted intervals and results in enhanced stimulation. The application of the IDD methodology is a fit-for-purpose solution to address the unique challenges of openhole operations, formation technical difficulties, high-stakes economics, and untapped high potential from intermittent reservoirs. By utilizing this application in one continuous operation, the use of chemical diverters, straddle packers and mechanical plugs for selective treatment in open hole is eliminated, making this multistage completion technology economical for these depleted wells. The paper presents results obtained after stimulating multiple zones along the lateral and describes the lessons learned in the implementation of this methodology. Going forward, the methods described, which can be considered a best practice for application to similar challenges in other fields. Proper candidate selection, optimum completion tools, and the fluid combination of in-situ gel-based diverter used to temporary plug the acid stimulated zone and foamed acid created an increase in the oil production of 430 BOPD.

Migration to Cased Hole Petrophysics: Are We Ready?

2021 ◽  
Author(s):  
Ulises Bustos ◽  
Carlos Duran ◽  
Alexander Duarte ◽  
Alfonso Salguero ◽  
Yira Vasquez ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Neutron Cross Section ◽  
Northern Region ◽  
Wellbore Stability ◽  
Total Carbon ◽  
Hole Formation ◽  
Formation Evaluation ◽  
Simultaneous Inversion ◽  
Well Completion ◽  
Open Hole

Abstract In the present Oil & Gas business context, the uncertainties reduction for hydrocarbon production increase in an operational costs and risk reduction scheme, are among the main drivers in several operating companies in the northern region of South America (Colombia & Ecuador). Electrical logging and drilling tools stuck events due to differential pressures, fishing operations, high wellbore tortuosity, difficult geometries and unconsolidated formations affecting wellbore stability, are among the main problems increasing non-productive time and operating costs. Minimizing open hole operations with a full migration to cased hole data acquisition, providing inputs for petrophysical uncertainty reductions without jeopardizing well completion decisions or initial reservoir characterization, would constitute an attractive solution for operators. Following those initiatives, we start by achieving a complete open hole formation evaluation and then migrating to case hole data acquisition and petrophysical assessment while benchmarking against open hole results. Low and variable formation water salinity, complex mineralogy's affecting resistivity and radioactive minerals, are common petrophysical challenges in our reservoirs. We had to implement Archie and salinity-independent formation evaluation solutions with cased hole technologies and in absence of open hole logs. The open hole petrophysics consist on simultaneous assessment of matrix and fluids saturations, while evaluating the oil mobility and water cut with the incorporation of multi-depth of investigation sensors in single logging runs (spectroscopy, dielectric dispersion, and magnetic resonance). We then moved to cased hole formation evaluation, with spectroscopy & nuclear-based petrophysics in gas, light oil, and heavy oil-bearing reservoirs. By implementation of non-archie fluids volumetric computation (that relies on conversion of dry weight total carbon to oil saturation and fast neutron cross section to gas saturation- done through a simultaneous inversion by solving matrix-porosity-fluids volumes into an elemental analysis), we obtained a representative formation saturation range behind casing. We then discussed on the different scenarios were migrating to cased hole is sustainable and its potential limitations.

Multistage Openhole Completion Using Integrated Dynamic Diversion Frac Technique in Highly Depleted Well: First Successful Application in West Kuwait Field

2021 ◽  
Author(s):  
Abdullah Abu-Eida ◽  
Salem Al-Sabea ◽  
Milan Patra ◽  
Bader Akbar ◽  
Kutbuddin Bhatia ◽  
...  
Keyword(s):  
Best Practice ◽  
Treatment Options ◽  
High Energy ◽  
Lessons Learned ◽  
High Potential ◽  
Fracture Plane ◽  
Fluid Loss ◽  
Field Development ◽  
Two Fluids

Abstract The Minagish field in West Kuwait is a high potential field which poses several challenges in terms of hydrocarbon flow assurance through highly depleted tight carbonate intervals with uneven reservoir quality and curtailed mobility. These conditions have shifted the field development from vertical to horizontal wellbore completions. Achieving complete wellbore coverage is a challenge for any frac treatment performed in a long openhole lateral with disparities in reservoir characteristics. The fluid will flow into the path of least resistance leaving large portions of the formation untreated. As a result, economic fracturing treatment options dwindle significantly, thus reservoir stimulation results are not always optimum. A multistage fracturing technique using Integrated Dynamic Diversion (IDD) has been performed first time in West Kuwait field well. The process uses active fluid energy to divert flow into a specific fracture point in the lateral, which can initiate and precisely place a fracture. The process uses two self-directed fluid streams: one inside the pipe and one in the annulus. The process mixes the two fluids downhole with high energy to form a consistent controllable mixture. The technique includes pinpoint fluid jetting at the point of interest, followed by in-situ HCL based crosslinked systems employed for improving individual stage targets. The IDD diversion shifts the fracture to unstimulated areas to create complex fractures which increases reservoir contact volume and improved overall conductivity in the lateral. The kinetic and chemical diversion of the IDD methodology is highly critical to control fluid loss in depleted intervals and results in enhanced stimulation. Pumping a frac treatment in openhole without control would tend to initiate a longitudinal fracture along the wellbore and may restrict productivity. By using specialized completion tools with nozzles at the end of the treating string, a new pinpoint process has been employed to initiate a transverse fracture plane in IDD applications. Proper candidate selection and fluid combination with in-situ crosslink acid effectively plug the fracture generated previously and generate pressure high enough to initiate another fracture for further ramification. By combining these processes into one continuous operation, the use of wireline/coiled tubing for jetting, plug setting and milling is eliminated, making the new multistage completion technology economical for these depleted wells. The application of the IDD methodology is a fit-for-purpose solution to address the unique challenges of openhole operations, formation technical difficulties, high-stakes economics, and untapped high potential from intermittent reservoirs. The paper will present post-operation results of this completion from all fractured zones along the lateral and will describe the lessons learned in implementation of this methodology which can be considered as best practice for application in similar challenges in other fields.

scholarly journals The Arab Formation in central Abu Dhabi: 3-D reservoir architecture and static and dynamic modeling

GeoArabia ◽  
2003 ◽  
Vol 8 (1) ◽  
pp. 47-86 ◽  
Author(s):  
Jürgen Grötsch ◽  
Omar Suwaina ◽  
Ghiath Ajlani ◽  
Ahmed Taher ◽  
Reyad El-Khassawneh ◽  
...  
Keyword(s):  
Dynamic Modeling ◽  
Fourth Order ◽  
High Energy ◽  
Development Planning ◽  
Abu Dhabi ◽  
Small Scale ◽  
Reservoir Properties ◽  
Depositional Facies ◽  
Well Completion ◽  
Fifth Order

ABSTRACT A 3-D geological model of the Kimmeridgian-Tithonian Manifa, Hith, Arab, and Upper Diyab formations in the area of the onshore Central Abu Dhabi Ridge was based on a newly established sequence stratigraphic, sedimentologic, and diagenetic model. It was part of an inter-disciplinary study of the large sour-gas reserves in Abu Dhabi that are mainly hosted by the Arab Formation. The model was used for dynamic evaluations and recommendations for further appraisal and development planning in the studied field. Fourth-order aggradational and progradational cycles are composed of small-scale fifth-order shallowing-upward cycles, mostly capped by anhydrite within the Arab-ABC. The study area is characterized by a shoreline progradation of the Arab Formation toward the east-northeast marked by high-energy oolitic/bioclastic grainstones of the Upper Arab-D and the Asab Oolite. The Arab-ABC, Hith, and Manifa pinch out toward the northeast. The strongly bioturbated Lower Arab-D is an intrashelf basinal carbonate ramp deposit, largely time-equivalent to the Arab-ABC. The deposition of the Manifa Formation over the Arab Formation was a major back-stepping event of the shallow-water platform before the onset of renewed progradation in the Early Cretaceous. Well productivity in the Arab-ABC is controlled mainly by thin, permeable dolomitic streaks in the fifth-order cycles at the base of the fourth-order cycles. This has major implications for reservoir management, well completion and stimulation, and development planning. Good reservoir properties have been preserved in the early diagenetic dolomitic streaks. In contrast, the reservoir properties of the Upper Arab-D oolitic/bioclastic grainstones deteriorate with depth due to burial diagenesis. A rock-type scheme was established because complex diagenetic overprinting prevented the depositional facies from being directly related to petrophysical properties. Special core analysis and the attribution of saturation functions to static and dynamic models were made on a cell-by-cell basis using the scheme and honoring the 3-D depositional facies and property model. The results demonstrated the importance of integrating sedimentological analysis and diagenesis with rock typing and static and dynamic modeling so as to enhance the predictive capabilities of subsurface models.

scholarly journals Nondestructive Study of Iron Artifacts using High-energy X-ray and Pulsed Neutron

hamon ◽  
2015 ◽  
Vol 25 (1) ◽  
pp. 8-12
Author(s):  
Manako Tanaka
Keyword(s):  
High Energy ◽  
X Ray ◽  
Iron Artifacts ◽  
Pulsed Neutron

Drilling, Completion, and Open-Hole Formation Evaluation of High-Angle HPHT Wells in High Density Cesium Formate Brine: The Kvitebjorn Experience, 2004-2006

2007 ◽  
Author(s):  
Per Cato Berg ◽  
Erik Sandtorv Pedersen ◽  
Aashild Lauritsen ◽  
Nader Behjat ◽  
Siri Hagerup-Jenssen ◽  
...  
Keyword(s):  
High Density ◽  
High Angle ◽  
Hole Formation ◽  
Formation Evaluation ◽  
Open Hole

Improving Well Completion via Real-Time Microseismic Monitoring: A West Texas Case Study

2010 ◽  
Author(s):  
Efejera Akpodiate Ejofodomi ◽  
Malcolm Yates ◽  
Robert Downie ◽  
Tarik Itibrout ◽  
O.A. Catoi
Keyword(s):  
Real Time ◽  
Microseismic Monitoring ◽  
Well Completion ◽  
West Texas
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