The real-time monitoring of fracture propagation during hydraulic fracturing is crucial for obtaining a deeper understanding of fracture morphology and optimizing hydraulic fracture designs.Accurate measurements of ke...The real-time monitoring of fracture propagation during hydraulic fracturing is crucial for obtaining a deeper understanding of fracture morphology and optimizing hydraulic fracture designs.Accurate measurements of key fracture parameters,such as the fracture height and width,are particularly important to ensure efficient oilfield development and precise fracture diagnosis.This study utilized the optical frequency domain reflectometer(OFDR)technique in physical simulation experiments to monitor fractures during indoor true triaxial hydraulic fracturing experiments.The results indicate that the distributed fiber optic strain monitoring technology can efficiently capture the initiation and expansion of fractures.In horizontal well monitoring,the fiber strain waterfall plot can be used to interpret the fracture width,initiation location,and expansion speed.The fiber response can be divided into three stages:strain contraction convergence,strain band formation,and postshutdown strain rate reversal.When the fracture does not contact the fiber,a dual peak strain phenomenon occurs in the fiber and gradually converges as the fracture approaches.During vertical well monitoring in adjacent wells,within the effective monitoring range of the fiber,the axial strain produced by the fiber can represent the fracture height with an accuracy of 95.6%relative to the actual fracture height.This study provides a new perspective on real-time fracture monitoring.The response patterns of fiber-induced strain due to fractures can help us better understand and assess the dynamic fracture behavior,offering significant value for the optimization of oilfield development and fracture diagnostic techniques.展开更多
Water hammer diagnostics is an important fracturing diagnosis technique to evaluate fracture locations and other downhole events in fracturing. The evaluation results are obtained by analyzing shut-in water hammer pre...Water hammer diagnostics is an important fracturing diagnosis technique to evaluate fracture locations and other downhole events in fracturing. The evaluation results are obtained by analyzing shut-in water hammer pressure signal. The field-sampled water hammer signal is often disturbed by noise interference. Noise interference exists in various pumping stages during water hammer diagnostics, with significantly different frequency range and energy distribution. Clarifying the differences in frequency range and energy distribution between effective water hammer signals and noise is the basis of setting specific filtering parameters, including filtering frequency range and energy thresholds. Filtering specifically could separate the effective signal and noise, which is the key to ensuring the accuracy of water hammer diagnosis. As an emerging technique, there is a lack of research on the frequency range and energy distribution of effective signals in water hammer diagnostics. In this paper, the frequency range and energy distribution characteristics of field-sampled water hammer signals were clarified quantitatively and qualitatively for the first time by a newly proposed comprehensive water hammer segmentation-energy analysis method. The water hammer signals were preprocessed and divided into three segments, including pre-shut-in, water hammer oscillation, and leak-off segment. Then, the three segments were analyzed by energy analysis and correlation analysis. The results indicated that, one aspect, the frequency range of water hammer oscillation spans from 0 to 0.65 Hz, considered as effective water hammer signal. The pre-shut-in and leak-off segment ranges from 0 to 0.35 Hz and 0-0.2 Hz respectively. Meanwhile, odd harmonics were manifested in water hammer oscillation segment, with the harmonic frequencies ranging approximately from 0.07 to 0.75 Hz. Whereas integer harmonics were observed in pre-shut-in segment, ranging from 6 to 40 Hz. The other aspect, the energy distribution of water hammer signals was analyzed in different frequency ranges. In 0-1 Hz, an exponential decay was observed in all three segments. In 1-100 Hz, a periodical energy distribution was observed in pre-shut-in segment, an exponential decay was observed in water hammer oscillation, and an even energy distribution was observed in leak-off segment. In 100-500 Hz, an even energy distribution was observed in those three segments, yet the highest magnitude was noted in leak-off segment. In this study, the effective frequency range and energy distribution characteristics of the field-sampled water hammer signals in different segments were sufficiently elucidated quantitatively and qualitatively for the first time, laying the groundwork for optimizing the filtering parameters of the field filtering models and advancing the accuracy of identifying downhole event locations.展开更多
Fiber-optic distributed strain sensing(FO-DSS)has been successful in monitoring strain changes along horizontal wellbores in hydraulically fractured reservoirs.However,the mechanism driving the various FO-DSS response...Fiber-optic distributed strain sensing(FO-DSS)has been successful in monitoring strain changes along horizontal wellbores in hydraulically fractured reservoirs.However,the mechanism driving the various FO-DSS responses associated with near-wellbore hydraulic fracture properties is still unclear.To address this knowledge gap,we use coupled wellbore-reservoir-geomechanics simulations to study measured strain-change behavior and infer hydraulic fracture characteristics.The crossflow among fractures is captured through explicit modeling of the transient wellbore flow.In addition,local grid refinement is applied to accurately capture strain changes along the fiber.A Base Case model was designed with four fractures of varying properties,simulating strain change signals when the production well is shut-in for 10 d after 240 d of production and reopened for 2 d.Strain-pressure plots for different fracture clusters were used to gain insights into inferring fracture properties using DSS data.When comparing the model with and without the wellbore,distinct strain change signals were observed,emphasizing the importance of incorporating the wellbore in FO-DSS modeling.The effects of fracture spacing and matrix permeability on strain change signals were thoroughly investigated.The results of our numerical study can improve the understanding of the relation between DSS signals and fracture hydraulic properties,thus maximizing the value of the dataset for fracture diagnostics and characterization.展开更多
In this study,flowback-assisted minifrac tests were conducted in low-permeability shale and salt formations to measure the in situ stress.An injection/flowback testing protocol was implemented in each test to achieve ...In this study,flowback-assisted minifrac tests were conducted in low-permeability shale and salt formations to measure the in situ stress.An injection/flowback testing protocol was implemented in each test to achieve accuracy and efficiency.Accurate and efficient injection/flowback testing is very important,given the impermeable nature of these formations and the need to complete each test as quickly as possible.Each flowback cycle yields a distinct and repeatable fracture closure signature,simplifying the interpretation of the fracture closure pressure.The objective of this paper is to share our field experience and to present a numerical analysis of the flowback test pressure responses,fracture closure behaviors,and fracture closure diagnostic methods.Examples from open-hole and casedhole minifrac tests are used to demonstrate site operation procedures.Then,two numerical models are presented for simulating the fracture closure behavior during a flowback test.Field evidence is provided to demonstrate that the fracture closure pressures from the flowback tests are identical to those from tests without flowback.The fracture closure diagnostic methods for flowback tests are discussed,and it is found that the G-function diagnostic method yields a distinct fracture closure signal during the flowback tests.This study is intended to provide additional insights regarding flowback tests by sharing our successes,experience,and knowledge,thereby benefiting the industry.展开更多
A 34-year-old man with a subtrochanteric osteoid osteoma localized to the lateral cortex of the left femur is reported. The patient presented with mild spontaneous pain of the lateral thigh and knee. He refused a radi...A 34-year-old man with a subtrochanteric osteoid osteoma localized to the lateral cortex of the left femur is reported. The patient presented with mild spontaneous pain of the lateral thigh and knee. He refused a radiographic examination and was treated as a greater trochanteric pa in syndrome for 9 months. He was then admitted with a transcervical fracture of the neck of the left femur after a fall from standing height. The fracture was fixed with 3 cannulated screws and healed uneventfully. His symptoms worsened after the first postoperative year. Eighteen months postoperatively the pain was dull, worsening at night, and relieved only with anti-inflammatory drugs, and he had a limp. New radiographs and tomograms were indicative of a lateral subtrochanteric osteoid osteoma with a subperiosteal localization. The lesion was treated successfully with surgical excision of a piece of reactive bone including the nidus.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52104060)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2021QE015).
文摘The real-time monitoring of fracture propagation during hydraulic fracturing is crucial for obtaining a deeper understanding of fracture morphology and optimizing hydraulic fracture designs.Accurate measurements of key fracture parameters,such as the fracture height and width,are particularly important to ensure efficient oilfield development and precise fracture diagnosis.This study utilized the optical frequency domain reflectometer(OFDR)technique in physical simulation experiments to monitor fractures during indoor true triaxial hydraulic fracturing experiments.The results indicate that the distributed fiber optic strain monitoring technology can efficiently capture the initiation and expansion of fractures.In horizontal well monitoring,the fiber strain waterfall plot can be used to interpret the fracture width,initiation location,and expansion speed.The fiber response can be divided into three stages:strain contraction convergence,strain band formation,and postshutdown strain rate reversal.When the fracture does not contact the fiber,a dual peak strain phenomenon occurs in the fiber and gradually converges as the fracture approaches.During vertical well monitoring in adjacent wells,within the effective monitoring range of the fiber,the axial strain produced by the fiber can represent the fracture height with an accuracy of 95.6%relative to the actual fracture height.This study provides a new perspective on real-time fracture monitoring.The response patterns of fiber-induced strain due to fractures can help us better understand and assess the dynamic fracture behavior,offering significant value for the optimization of oilfield development and fracture diagnostic techniques.
基金support from the National Natural Science Foundation of China(No.52374019).
文摘Water hammer diagnostics is an important fracturing diagnosis technique to evaluate fracture locations and other downhole events in fracturing. The evaluation results are obtained by analyzing shut-in water hammer pressure signal. The field-sampled water hammer signal is often disturbed by noise interference. Noise interference exists in various pumping stages during water hammer diagnostics, with significantly different frequency range and energy distribution. Clarifying the differences in frequency range and energy distribution between effective water hammer signals and noise is the basis of setting specific filtering parameters, including filtering frequency range and energy thresholds. Filtering specifically could separate the effective signal and noise, which is the key to ensuring the accuracy of water hammer diagnosis. As an emerging technique, there is a lack of research on the frequency range and energy distribution of effective signals in water hammer diagnostics. In this paper, the frequency range and energy distribution characteristics of field-sampled water hammer signals were clarified quantitatively and qualitatively for the first time by a newly proposed comprehensive water hammer segmentation-energy analysis method. The water hammer signals were preprocessed and divided into three segments, including pre-shut-in, water hammer oscillation, and leak-off segment. Then, the three segments were analyzed by energy analysis and correlation analysis. The results indicated that, one aspect, the frequency range of water hammer oscillation spans from 0 to 0.65 Hz, considered as effective water hammer signal. The pre-shut-in and leak-off segment ranges from 0 to 0.35 Hz and 0-0.2 Hz respectively. Meanwhile, odd harmonics were manifested in water hammer oscillation segment, with the harmonic frequencies ranging approximately from 0.07 to 0.75 Hz. Whereas integer harmonics were observed in pre-shut-in segment, ranging from 6 to 40 Hz. The other aspect, the energy distribution of water hammer signals was analyzed in different frequency ranges. In 0-1 Hz, an exponential decay was observed in all three segments. In 1-100 Hz, a periodical energy distribution was observed in pre-shut-in segment, an exponential decay was observed in water hammer oscillation, and an even energy distribution was observed in leak-off segment. In 100-500 Hz, an even energy distribution was observed in those three segments, yet the highest magnitude was noted in leak-off segment. In this study, the effective frequency range and energy distribution characteristics of the field-sampled water hammer signals in different segments were sufficiently elucidated quantitatively and qualitatively for the first time, laying the groundwork for optimizing the filtering parameters of the field filtering models and advancing the accuracy of identifying downhole event locations.
基金funding support from the National Natural Science Foundation of China(Grant No.52204030)Youth Innovation and Technology Support Program for Higher Education Institutions of Shandong Province,China(Grant No.2022KJ070)the National Natural Science Foundation of China Enterprise Innovation and Development Joint Fund Project(Grant No.U19B6003).
文摘Fiber-optic distributed strain sensing(FO-DSS)has been successful in monitoring strain changes along horizontal wellbores in hydraulically fractured reservoirs.However,the mechanism driving the various FO-DSS responses associated with near-wellbore hydraulic fracture properties is still unclear.To address this knowledge gap,we use coupled wellbore-reservoir-geomechanics simulations to study measured strain-change behavior and infer hydraulic fracture characteristics.The crossflow among fractures is captured through explicit modeling of the transient wellbore flow.In addition,local grid refinement is applied to accurately capture strain changes along the fiber.A Base Case model was designed with four fractures of varying properties,simulating strain change signals when the production well is shut-in for 10 d after 240 d of production and reopened for 2 d.Strain-pressure plots for different fracture clusters were used to gain insights into inferring fracture properties using DSS data.When comparing the model with and without the wellbore,distinct strain change signals were observed,emphasizing the importance of incorporating the wellbore in FO-DSS modeling.The effects of fracture spacing and matrix permeability on strain change signals were thoroughly investigated.The results of our numerical study can improve the understanding of the relation between DSS signals and fracture hydraulic properties,thus maximizing the value of the dataset for fracture diagnostics and characterization.
文摘In this study,flowback-assisted minifrac tests were conducted in low-permeability shale and salt formations to measure the in situ stress.An injection/flowback testing protocol was implemented in each test to achieve accuracy and efficiency.Accurate and efficient injection/flowback testing is very important,given the impermeable nature of these formations and the need to complete each test as quickly as possible.Each flowback cycle yields a distinct and repeatable fracture closure signature,simplifying the interpretation of the fracture closure pressure.The objective of this paper is to share our field experience and to present a numerical analysis of the flowback test pressure responses,fracture closure behaviors,and fracture closure diagnostic methods.Examples from open-hole and casedhole minifrac tests are used to demonstrate site operation procedures.Then,two numerical models are presented for simulating the fracture closure behavior during a flowback test.Field evidence is provided to demonstrate that the fracture closure pressures from the flowback tests are identical to those from tests without flowback.The fracture closure diagnostic methods for flowback tests are discussed,and it is found that the G-function diagnostic method yields a distinct fracture closure signal during the flowback tests.This study is intended to provide additional insights regarding flowback tests by sharing our successes,experience,and knowledge,thereby benefiting the industry.
文摘A 34-year-old man with a subtrochanteric osteoid osteoma localized to the lateral cortex of the left femur is reported. The patient presented with mild spontaneous pain of the lateral thigh and knee. He refused a radiographic examination and was treated as a greater trochanteric pa in syndrome for 9 months. He was then admitted with a transcervical fracture of the neck of the left femur after a fall from standing height. The fracture was fixed with 3 cannulated screws and healed uneventfully. His symptoms worsened after the first postoperative year. Eighteen months postoperatively the pain was dull, worsening at night, and relieved only with anti-inflammatory drugs, and he had a limp. New radiographs and tomograms were indicative of a lateral subtrochanteric osteoid osteoma with a subperiosteal localization. The lesion was treated successfully with surgical excision of a piece of reactive bone including the nidus.
