The Experts below are selected from a list of 162696 Experts worldwide ranked by ideXlab platform
Zoya Heidari - One of the best experts on this subject based on the ideXlab platform.
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a new method for quantifying cation exchange capacity method verification and application to organic rich mudrock Formations
Applied Clay Science, 2019Co-Authors: Kai Cheng, Zoya HeidariAbstract:Abstract In this paper, a new method is proposed to quantify cation exchange capacity (CEC) in organic-rich mudrocks with complex mineralogy and in the presence of multiple types of clay minerals by integrating nitrogen adsorption-desorption, nuclear magnetic resonance (NMR), pyrolysis, and X-ray diffraction (XRD) measurements (including quantitative XRD). The CEC estimates from the new method were compared against CEC estimates from the wet chemistry method in powdered organic-rich mudrock samples and the membrane potential method in intact mudrock samples. The estimated CEC from the new method agreed with those obtained from the membrane potential method, with average relative error of less than 10%. The CEC estimates from these two methods fell within the upper and lower bounds of CEC estimates, calculated based on the reported data for pure clay minerals, but the results the wet chemistry method showed significant overestimates of the CEC Evaluation. Sensitivity analysis was also carried out to evaluate the influence of CEC estimates from different methods on assessment of water saturation and demonstrated the importance of CEC Evaluation and the impact of the new method on enhanced Formation Evaluation.
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Assessment of Residual Hydrocarbon Saturation with the Combined Quantitative Interpretation of Resistivity and Nuclear Logs
Petrophysics, 2011Co-Authors: Zoya Heidari, Alberto Mendoza, Carlos Torres-verdín, Gong Li WangAbstract:Estimation of residual hydrocarbon saturation remains an outstanding challenge in Formation Evaluation and core analysis. Standard interpretation methods for nuclear-resistivity logs cannot distinguish between mobile and residual hydrocarbon saturation. In extreme cases, fluid pumpout or production testing are the only options to ascertain whether the reservoir's in-situ hydrocarbon is mobile. We develop a new method to distinguish mobile from residual hydrocarbon and to quantify residual hydrocarbon saturation. The method combines modeling of resistivity and nuclear logs with the physics of mud-filtrate invasion to quantify the effect of residual hydrocarbon saturation on both nuclear and resistivity logs. This strategy explicitly takes into account the different volumes of investigation of resistivity and nuclear measurements and does not assume that the near-borehole region is flushed to the level of residual hydrocarbon saturation. The method begins with an initial multi-layer petrophysical model which is constructed via standard procedures of well-log interpretation and core measurements. Thereafter, we simulate the physics of mud-filtrate invasion and the corresponding resistivity, density, and neutron logs. Initial estimates of residual hydrocarbon saturation and parametric relative permeability are refined until achieving a good agreement between simulated and measured neutron and density logs. Next, we refine initial estimates of water saturation, porosity, and permeability until securing a good match between numerically simulated and measured resistivity logs. The method of interpretation considers two specific options for implementation: (1) quantification of the influence of residual hydrocarbon saturation on the radial distribution of fluid saturation due to invasion, and (2) appraisal of invasion effects on the vertical distribution of fluid saturation within a flow unit that exhibits both hydrocarbon and water saturation in capillary equilibrium. Application examples are described for the cases of tight-gas sand reservoirs invaded with water-base mud (WBM) and oil-bearing reservoirs invaded with oil-base mud (OBM). In the case of tight-gas sands, our method explains the marginal productivity of deeply invaded beds that exhibit cross-over between density and neutron logs. For a 15-porosity unit Formation, when the residual gas saturation increases by 10 saturation units, the cross-over between neutron and density logs increases by 2.4 porosity units. Interpretation results indicate measurable sensitivity of nuclear logs to residual hydrocarbon saturation in cases of deep WBM invasion due to immiscibility between invaded and in-situ fluids. However, the accuracy of the method decreases with increasing values of both hydrocarbon pore volume and hydrocarbon density. In the case of OBM invasion, reliable estimations of residual hydrocarbon saturation are possible with relative density differences above 15 percent between mud filtrate and in-situ hydrocarbon.
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improving the assessment of residual hydrocarbon saturation with the combined quantitative interpretation of resistivity and nuclear logs
SPWLA 50th Annual Logging Symposium, 2009Co-Authors: Zoya Heidari, Alberto Mendoza, Carlos Torresverdin, Gong Li WangAbstract:Estimation of residual hydrocarbon saturation remains an outstanding problem in Formation Evaluation. Standard interpretation methods for nuclear-resistivity logs cannot distinguish between mobile and trapped hydrocarbon saturation. In extreme cases, fluid pumpout and production testing are the only options to differentiate between moveable and residual hydrocarbon saturation. We develop a new method to diagnose and quantify residual hydrocarbon saturation that combines resistivity and nuclear logs with the physics of mud-filtrate invasion. An initial multi-layer petrophysical model is constructed with standard procedures of well-log interpretation and core measurements. Thereafter, we simulate the physics of mud-filtrate invasion and the corresponding resistivity, density, and neutron logs. We refine the initial estimate of residual hydrocarbon saturation of relative permeability curves until achieving a good agreement between simulated and measured neutron and density logs. Subsequently, we refine initial estimates of water saturation, porosity, and permeability until securing a good match between numerically simulated and measured resistivity logs. The method of interpretation considers two specific options for implementation: (1) quantification of the influence of residual hydrocarbon saturation on the radial distribution of fluid saturation due to invasion, and (2) appraisal of invasion effects on the vertical distribution of fluid saturation within a flow unit that exhibits both hydrocarbon and water saturation in capillary equilibrium. We describe application examples for the cases of tight-gas sand reservoirs invaded with water-base mud (WBM) and oil-bearing reservoirs invaded with oilbase mud (OBM). In the case of tight-gas sands, our method explains the marginal producibility of deeply invaded beds that exhibit cross-over between density and neutron logs. For a 0.15-porosity Formation, the cross-over between neutron and density logs increases by 2.4 porosity units when residual gas saturation increases by 0.1. Interpretation results indicate measurable sensitivity of nuclear logs to residual hydrocarbon saturation in cases of deep WBM invasion due to immiscibility between invaded and in-situ fluids. However, the accuracy of the method decreases with increasing values of porosity. In the case of OBM invasion, reliable estimations of residual hydrocarbon saturation are possible with relative density differences above 15% between mud filtrate and in-situ hydrocarbon.
Lizhi Xiao - One of the best experts on this subject based on the ideXlab platform.
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design of a new lwd nmr tool with high mechanical reliability
Journal of Magnetic Resonance, 2020Co-Authors: Zhe Sun, Lizhi Xiao, Guangzhi Liao, Xueli Hou, Zhong ChenAbstract:Abstract Nuclear magnetic resonance (NMR) provides useful inFormation for Formation Evaluation on pore size and pore volume. Depending on field operations, there are two types of borehole NMR: wireline logging and logging-while-drilling (LWD). The latter type is more convenient. But due to the high mechanical failure risk caused by insufficient mechanical strength of the tool and vibrations during measurement, the quality of LWD NMR measurements are severely affected. In this paper, to enable high reliability and vibration tolerance, we propose a new design and implement a new LWD NMR tool, whose features includes a double hollow cylindric magnet (DHCM) structure and a solenoid-optimized antenna. The DHCM structure greatly reduces the proportion of the magnet in the cross-section of the tool without reducing B0 field strength. Thus, the mechanical strength and the reliability of the tool is greatly improved. The antenna is improved by optimizing the parameters of each coil of the solenoid for finding the generated B1 distribution best matching B0. The new design has a saddle sensing area in the axial and radial plane with a width greater than 50 mm, which is wide enough to ensure the validity of the T2 measurement under strong vibrations. We had demonstrated that this new tool performs well when TE = 0.6 ms, ensuring the measurement richness is suitable for LWD prospecting for unconventional oil and gas reservoirs. Besides, this design is suitable for that in slim holes.
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the downhole circumferential scanning magnetic resonance imaging tool
Magnetic Resonance Imaging, 2019Co-Authors: Wei Liu, Lizhi Xiao, Guangzhi Liao, Yan Zhang, Sihui LuoAbstract:Abstract The downhole circumferential scanning magnetic resonance logging is able to image saturation distribution and fluid properties of stratum around a borehole, thus providing relevant and abundant inFormation for Formation Evaluation. The device employs a phase-controlled excitation device based on combined array structure to accomplish three dimensional data acquisition from axial, radial and circumferential directions. This paper focuses on the design principle of device and the structure of electronic control system. A mutual coupling analysis with array antenna was carried out using inductance coupling principle, and realize the decoupling and energy discharge compensation of array antennas. The circumferential scanning nuclear magnetic resonance technique has a potential of overcoming the weakness of two dimensional measurements and raising new applications that it determines the azimuth of the fluid in the borehole and realizes the imaging measurement of the pore structure and the reservoir fluid.
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a new downhole magnetic resonance imaging tool
Microporous and Mesoporous Materials, 2018Co-Authors: Wei Liu, Lizhi Xiao, Sihui Luo, Guangzhi Liao, Yan Zhang, Zhe Sun, Xueli HouAbstract:Abstract This paper presents a novel inside-out magnetic resonance imaging (MRI) device with axial, radial and circumferential measurements. The designed MRI probe employs array antenna and phase-controlled transmitters to accomplish spin echo data acquisition. Nuclear Magnetic Resonance (NMR) has been successfully applied to downhole Formation Evaluation with unique inFormation of in-situ reservoir properties for decades. Traditional NMR logging measurements, however, are averaged the whole sensitive volume. The designed downhole MRI tool overcomes the weakness of traditional technique and raise new applications such as for heterogeneous Formation Evaluation around well bore and for harsh borehole conditions. We demonstrate the feasibility with a prototype in a calibration tank. The acquired echo trains from different direction and different radial depth are in good quality.
Kiyofumi Suzuki - One of the best experts on this subject based on the ideXlab platform.
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characterization and prediction of the gas hydrate reservoir at the second offshore gas production test site in the eastern nankai trough japan
Energies, 2017Co-Authors: Machiko Tamaki, Tetsuya Fujii, Kiyofumi SuzukiAbstract:Following the world’s first offshore production test that was conducted from a gas hydrate reservoir by a depressurization technique in 2013, the second offshore production test has been planned in the eastern Nankai Trough. In 2016, the drilling survey was performed ahead of the production test, and logging data that covers the reservoir interval were newly obtained from three wells around the test site: one well for geological survey, and two wells for monitoring surveys, during the production test. The Formation Evaluation using the well log data suggested that our target reservoir has a more significant heterogeneity in the gas hydrate saturation distribution than we expected, although lateral continuity of sand layers is relatively good. To evaluate the spatial distribution of gas hydrate, the integration analysis using well and seismic data was performed. The seismic amplitude analysis supports the lateral reservoir heterogeneity that has a significant positive correlation with the resistivity log data at the well locations. The spatial distribution of the apparent low-resistivity interval within the reservoir observed from log data was investigated by the P-velocity volume derived from seismic inversion. The integrated results were utilized for the pre-drill prediction of the reservoir quality at the producing wells. These approaches will reduce the risk of future commercial production from the gas hydrate reservoir.
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site selection and Formation Evaluation at the 1st offshore methane hydrate production test site in the eastern nankai trough japan
75th EAGE Conference and Exhibition - Workshops, 2013Co-Authors: Tetsuya Fujii, Kiyofumi Suzuki, S Noguchi, T Takayama, K Yamamoto, T SaekiAbstract:In order to evaluate productivity of gas from marine gas hydrate by the depressurization method, Japan Oil, Gas and Metals National Corporation is planning to conduct a full-scale production test in early 2013 at the AT1 site in the north slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. By the pre-drilling campaign conduced in early 2012, we confirmed methane hydrate concentrated zone (MHCZ) with 60 m of gross thickness, which is composed of lobe/sheet type sequences in the upper part of it and channel type sand sequences in the lower part. This MHCZ is thicker than that of confirmed at previous wells in 2004 (45 m) located around 150 m northeast, indicating that the prediction provided by seismic interpretation and inversion analysis was reasonable. Well-to-well correlation between two monitoring wells (AT1-MC and MT1) within 40 m distance exhibited that lateral continuity of these sand layers (upper part of reservoir) are fairly good, which representing ideal reservoir for the production test. The XPT fluid mobility measurement results showed approximately 0.1 to several mD of water permeability in both MHCZ and seal Formation, although there are some variations in measured values.
Zhiqiang Mao - One of the best experts on this subject based on the ideXlab platform.
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determination of reservoir wettability based on resistivity index prediction from core and log data
Journal of Petroleum Science and Engineering, 2021Co-Authors: Cheng Feng, Zhiqiang Mao, Jungui Feng, Ziyan Feng, Yuntao Zhong, Kegang LingAbstract:Abstract With the increasing demand of precisive reservoir characterization in exploration and development of oil and gas, wettability plays a more and more significant role because it influences oil and water distribution. The determination of wettability has been a challenge to the researchers focusing on this area. In this study, a new method is proposed for the determination of wettability based on resistivity index prediction. Firstly, the model for estimating resistivity index using capillary pressure, porosity and median pressure by J-function is derived. Secondly, the model to estimate resistivity index via T2 time, porosity and T2 geometric mean is derived, which combines J-function with Schlumberger-Doll-Research (SDR) model. Thirdly, a new parameter, the ratio of mean saturation index calculated from first method to the one calculated from second method, is used to determine the reservoir wettability. To calibrate and verify the established models, 30 cores were acquired for the petrophysical experiments. The experimental results of 25 cores are used to calibrate the established models and build the quantitative relationship between the wettability and the ratio of mean saturation index, with a relevance of 0.96. Besides, the calibrated model is tested by using the experiment data of the rest 5 cores. The estimated wettability conforms to the experimental results. Finally, the processing and interpreting results of log data also indicate that the proposed model for quantitative prediction of wettability features good application effect. In conclusion, the proposed method for quantitative prediction of wettability is effective and highly reliable, which solves a difficult problem in Formation Evaluation.
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A new empirical method for constructing capillary pressure curves from conventional logs in low-permeability sandstones
Journal of Earth Science, 2017Co-Authors: Cheng Feng, Yujiang Shi, Liang Chang, Zhiqiang MaoAbstract:Pore structure reflected from capillary pressure curves plays an important role in low-permeability Formation Evaluation. It is a common way to construct capillary pressure curves by Nuclear Magnetic Resonance (NMR) log. However, the method’s efficiency will be severely affected if there is no NMR log data or it cannot reflect pore structure well. Therefore, on the basis of J function and diagenetic facies classification, a new empirical model for constructing capillary pressure curves from conventional logs is proposed here as a solution to the problem. This model includes porosity and the relative value of natural gamma rays as independent variables and the saturation of mercury injection as a dependent variable. According to the 51 core experimental data sets of three diagenetic facies from the bottom of the Upper Triassic in the western Ordos Basin, China, the model’s parameters in each diagenetic facies are calibrated. Both self-checking and extrapolation tests show a positive effect, which demonstrates the high reliability of the proposed capillary pressure curve construction model. Based on the constructed capillary pressure curves, NMR T 2 spectra under fully brine-saturated conditions are mapped by a piecewise power function. A field study is then presented. Agreement can be seen between the mapped NMR T 2 spectra and the MRIL-P log data in the location of the major peak, right boundary, distribution characteristics and T 2 logarithmic mean value. In addition, the capillary pressure curve construction model proposed in this paper is not affected by special log data or Formation condition. It is of great importance in evaluating pore structure, predicting oil production and identifying oil layers through NMR log data in low-permeability sandstones.
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application of nmr logs in tight gas reservoirs for Formation Evaluation a case study of sichuan basin in china
Journal of Petroleum Science and Engineering, 2012Co-Authors: Liang Xiao, Zhiqiang Mao, Zhaonian Wang, Yan JinAbstract:Abstract Permeability, irreducible water saturation and other inFormation associated with the pore size, such as capillary pressure, are very important input parameters in tight gas reservoir Evaluation. Fortunately, those parameters can be well estimated from field NMR logs, if the proper calibrations between NMR relaxation time and capillary pressure were established with measurements from core samples. In this study, a novel calibration technique, which is used for constructing capillary pressure curve from NMR logs by combining the classical SDR model with J function, is proposed and the corresponding model is established. Based on the laboratory measurements of 54 plug samples taken from the Upper Triassic sandstone Formation (Xujiahe Formation) in Anlu district, Sichuan basin, Southwest China, the model parameters are calibrated. With the calibrations established and procedures proposed in this paper, the synthetic capillary pressure curves of reservoir can be constructed from field NMR spectrum. Also from those laboratory measurements, the parameter of K ϕ (defined as the pore structure index) can be well related to the Swanson's parameter derived from capillary pressure curve. This correlation could then be used for estimating reservoir permeability from the synthetic capillary pressure curve. After Formation is classified into three types by using the pore structure index, the pore throat radius cutoffs can be acquired to calculate irreducible water saturation from the pore throat radius distribution. The proposed techniques and procedures are applied in field logs and the estimated inFormation and parameters are well verified by core and drill stem testing data. By combining with the inFormation of reservoir pore structure, permeability and irreducible water saturation, potential low resistivity contrast gas bearing reservoirs can be identified from water layers.
Tetsuya Fujii - One of the best experts on this subject based on the ideXlab platform.
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characterization and prediction of the gas hydrate reservoir at the second offshore gas production test site in the eastern nankai trough japan
Energies, 2017Co-Authors: Machiko Tamaki, Tetsuya Fujii, Kiyofumi SuzukiAbstract:Following the world’s first offshore production test that was conducted from a gas hydrate reservoir by a depressurization technique in 2013, the second offshore production test has been planned in the eastern Nankai Trough. In 2016, the drilling survey was performed ahead of the production test, and logging data that covers the reservoir interval were newly obtained from three wells around the test site: one well for geological survey, and two wells for monitoring surveys, during the production test. The Formation Evaluation using the well log data suggested that our target reservoir has a more significant heterogeneity in the gas hydrate saturation distribution than we expected, although lateral continuity of sand layers is relatively good. To evaluate the spatial distribution of gas hydrate, the integration analysis using well and seismic data was performed. The seismic amplitude analysis supports the lateral reservoir heterogeneity that has a significant positive correlation with the resistivity log data at the well locations. The spatial distribution of the apparent low-resistivity interval within the reservoir observed from log data was investigated by the P-velocity volume derived from seismic inversion. The integrated results were utilized for the pre-drill prediction of the reservoir quality at the producing wells. These approaches will reduce the risk of future commercial production from the gas hydrate reservoir.
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site selection and Formation Evaluation at the 1st offshore methane hydrate production test site in the eastern nankai trough japan
75th EAGE Conference and Exhibition - Workshops, 2013Co-Authors: Tetsuya Fujii, Kiyofumi Suzuki, S Noguchi, T Takayama, K Yamamoto, T SaekiAbstract:In order to evaluate productivity of gas from marine gas hydrate by the depressurization method, Japan Oil, Gas and Metals National Corporation is planning to conduct a full-scale production test in early 2013 at the AT1 site in the north slope of Daini-Atsumi Knoll in the eastern Nankai Trough, Japan. By the pre-drilling campaign conduced in early 2012, we confirmed methane hydrate concentrated zone (MHCZ) with 60 m of gross thickness, which is composed of lobe/sheet type sequences in the upper part of it and channel type sand sequences in the lower part. This MHCZ is thicker than that of confirmed at previous wells in 2004 (45 m) located around 150 m northeast, indicating that the prediction provided by seismic interpretation and inversion analysis was reasonable. Well-to-well correlation between two monitoring wells (AT1-MC and MT1) within 40 m distance exhibited that lateral continuity of these sand layers (upper part of reservoir) are fairly good, which representing ideal reservoir for the production test. The XPT fluid mobility measurement results showed approximately 0.1 to several mD of water permeability in both MHCZ and seal Formation, although there are some variations in measured values.