Predicting oil saturation of shale-oil reservoirs using nuclear magnetic resonance logs

Kuang, Lichun; Wang, Zhenlin; Feng, Cheng; Zhao, Peiqiang; Mao, Rui; Yu, Jing

doi:10.1190/int-2019-0150.1

Cited by 10 publications

(4 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…NMR T 2 components longer than 7.0 ms are treated as oil signals in the Lucaogou Formation in the Jimusar Sag, NMR logs being used for oil saturation determination (the ratio of T 2 components larger than 7.0 ms to the total T 2 components > 0.3 ms) (Fig. 5) Kuang et al, 2020). The NMR-derived oil saturation has a good positive correlation with coremeasured oil saturation, indicating that NMR logs can be used for oil saturation calculation (Fig.…”

Section: Oiliness and Oil-bearing Propertymentioning

confidence: 99%

See 1 more Smart Citation

Geological and Engineering ‘Sweet Spots’ in the Permian Lucaogou Formation, Jimusar Sag, Junggar Basin

Lai

Bai

et al. 2023

Acta Geologica Sinica (Eng)

View full text Add to dashboard Cite

Unconventional oil and gas resources require petrophysical logs to answer the question “How to optimize the geological and engineering sweet spots?”. Therefore the establishment of key well with comprehensive descriptions of lithology, reservoir property, hydrocarbon bearing property, electronic well log responses, source rock property, brittleness, and in situ stress magnitude and direction is important for exploration and production of unconventional hydrocarbon resources. Cores, thin section, scanning electron microscopy (SEM) and comprehensive well log suits are used to build a key well of the Permian Lucaogou Formation, Jimusar Sag of Junggar Basin. The results show that there are mainly three types of lithologies including siltstone, mudstone, and dolostone. Lithologies can be predicted using the combination of conventional well and image logs. The pore spaces consist of interparticle pores, intragranular dissolution pores, and micropores. Nuclear Magnetic Resonance (NMR) T2 components longer than 1.7 ms are superposed as effective porosity. Permeability is calculated using the Coates model from NMR T2 spectra. The ratio of T2 components >7.0 ms to the T2 components >0.3 ms is used to calculate oil saturation. TOC is calculated using ΔlogR method. Brittleness index is calculated using Poisson‐ Young's method, and brittleness index ranges from 13.42%–70.53%. In situ stress direction is determined, and in situ stress magnitudes (Maximum horizontal stress SHmax, Minimum horizontal stress Shmin, Vertical stress Sv) are calculated using density and sonic logs. The strike‐slip stress type (SHmax>Sv>Shmin) is encountered. The key well which comprehensively includes the above seven properties is established. Then geological and engineering (geomechanical) sweet spots are optimized from the key well by fully analyzing lithology, reservoir property, oil bearing potential, in situ stress magnitude and brittleness. The results are hoped to support engineers' and geologists' decisions for exploitation of unconventional hydrocarbon resources.

show abstract

Section: Oiliness and Oil-bearing Propertymentioning

confidence: 99%

“…5. NMR T 2 spectrum and related pore and fluid distribution with various T 2 componentsKuang et al, 2020).…”

mentioning

confidence: 99%

Geological and Engineering ‘Sweet Spots’ in the Permian Lucaogou Formation, Jimusar Sag, Junggar Basin

Lai

Bai

et al. 2023

Acta Geologica Sinica (Eng)

View full text Add to dashboard Cite

show abstract

“…The Permian Lucaogou Formation from Jimusar Sag (Figure b) is a hot shale oil resource target. − The Jimusar Sag (Figure b) has been the first national shale oil demonstration area in China in 2020 . The sweet-spot intervals from the upper and lower Lucaogou Formation contribute to the majority of shale oil production.…”

Section: Geological Settingmentioning

confidence: 99%

Role of Organic Matter, Mineral, and Rock Fabric in the Full-Scale Pore and Fracture Network Development in the Mixed Lacustrine Source Rock System

et al. 2022

View full text Add to dashboard Cite

The mixed deposition constitutes the external clastic, intrabasinal, and pyroclastic components in both marine and lacustrine environments. The finegrained mixed lacustrine source rocks are rich in organic matter and present good unconventional energy resources. However, the mixed lacustrine source rock systems have extremely low permeabilities and need hydraulic fracturing to stimulate oil from the complex nanoscale matrix. The role of rock fabric, organic matter, and mineral compositions in full-scale pore structures is still unclear, especially for the source rock from a mixed sedimentary environment. This restricts sweet spot identification. Here, we use three groups of Permian Lucaogou source rock samples with fine laminated, thick laminated, and massive rock fabric to investigate the relationship between rock fabric, organic matter, and pore structure using a combination of mineralogy, organic geochemistry, low-pressure nitrogen adsorption, micro-CT, and mercury injection capillary pressure data. The results indicate that the Lucaogou source rocks mainly contain type I and type II kerogen and show good to excellent hydrocarbon generation potential. The source rock was deposited in a mixed environment with high contents of carbonate and less siliceous minerals, showing good frackability. The mineralogy-based ternary classification shows that the source rock mainly belongs to high total organic carbon (TOC > 4%) mixed carbonate mudstone and high TOC mixed mudstone. For mixed lacustrine source rock, the full-scale pore-fracture distribution shows that the average percentage values of pore volume for micropores (<10 nm), transitional pores (10−100 nm), mesopores (100−1000 nm), and macropores (fracture) (>1000 nm) are 11.14, 21.62, 10.77, and 56.47%, respectively. However, the average percentage values of pore surface area for the abovementioned pores are 62.45, 30.45, 5.47, and 1.63%, respectively. Both quartz and terrigenous clast present a weak-medium unimodal correlation with the TOC content. Both terrigenous clast and clay minerals control the source rock hydrocarbon generation potential. The carbonate and terrigenous clast mineral content play a significant role in micropores and transitional pores, while the clay mineral presents a negative impact on macropore development. The effect of rock fabric on shale oil potential is negligible compared with organic matter abundance. Shales with thick parallel laminae and medium TOC (2% < TOC < 4%) possess favorable shale oil potential.

show abstract

“…The LWD-NMR technology is a non-radioactive porosity measurement technique that can detect formation characteristics before or when mud filtrate intrusions are very shallow. Compared with traditional wireline NMR logging, it can more truly reflect reservoir characteristics with higher evaluation accuracy [1,2]. Due to the limitations of horizontal or highly deviated Wells, the LWD-NMR system cannot use wireline for data communication, and mud pulse telemetry with transmission rates of 4 to 10 bit/s is usually the only option [3,4].…”

Section: Introductionmentioning

confidence: 99%

FPGA-Based Real-time T2 Spectrum Inversion Algorithm for LWD-NMR Logging with Periodic Thermal Management

Fan

Liu

et al. 2023

Preprint

View full text Add to dashboard Cite

The LWD-NMR instruments are limited by the telemetry bandwidth and logging timing requirements, so the echo T2 spectrum inversion function must be implemented at downhole logging instruments. Firstly, the inversion problem of T2 spectrum is converted to a non-negative least squares problem and solved by the accelerated projective gradient descent (APGD) algorithm. Secondly, the distributed structure is used in FPGA design to shorten the time for the APGD algorithm. Finally, a software cooling method based on a multi-core structure and periodic thermal management technology is deployed. Therefore, the inversion algorithm of echo T2 spectrum deployed on FPGA not only meets the requirements of real-time inversion calculation but also reduces the temperature effectively by means of software cooling. It provides a useful reference for the research of the downhole data processing technology of LWD.

show abstract

Predicting oil saturation of shale-oil reservoirs using nuclear magnetic resonance logs

Cited by 10 publications

References 20 publications

Geological and Engineering ‘Sweet Spots’ in the Permian Lucaogou Formation, Jimusar Sag, Junggar Basin

Geological and Engineering ‘Sweet Spots’ in the Permian Lucaogou Formation, Jimusar Sag, Junggar Basin

Role of Organic Matter, Mineral, and Rock Fabric in the Full-Scale Pore and Fracture Network Development in the Mixed Lacustrine Source Rock System

FPGA-Based Real-time T2 Spectrum Inversion Algorithm for LWD-NMR Logging with Periodic Thermal Management

Contact Info

Product

Resources

About