In Dagang Oilfield in China,the utilization of the KCl polymer water-based drilling fluid(WBDF) in middeep exploration/appraisal wells presents a challenge in simultaneously optimizing resistivity logging accuracy and...In Dagang Oilfield in China,the utilization of the KCl polymer water-based drilling fluid(WBDF) in middeep exploration/appraisal wells presents a challenge in simultaneously optimizing resistivity logging accuracy and wellbore stability.To address this,it is necessary to conduct geology-engineering integration studies.Based on the formation resistivity,an analytical model was developed to assess the impact of KCl concentration in the WBDF on array induction logging response accuracy.The maximum permissible KCl concentration for the target formations was determined,and technical strategies were proposed to maintain wellbore stability at a reduced KCl concentration.After that,considering the inhibitory,encapsulating,and plugging effects,a low-KCl-concentration WBDF was optimized and applied.Model calculations demonstrate that increasing KCl concentration in the WBDF decreases resistivity,thereby reducing logging accuracy.To maintain a logging accu racy of ≥80%,the upper limits for KCl concentration in the WBDF are 4.8%,4.2%,and 3.6% for the 3rd Member of the Dongying Formation,the 1st and 2nd members of the Shahejie Formation,respectively.Cuttings recovery experiments revealed that a minimum KCl concentration of 3% is required to ensure basic shale inhibition.A combination of 3% KCl with 1% polyamine inhibitor yielded cuttings recovery and shale stability index comparable to those achieved with 7% KCl alone,and the shale inhibition performance was further enhanced with the addition of an encapsulator.The optimized WBDF has been successfully deployed in exploration/appraisal wells across multiple blocks within Dagang Oilfield,resulting in superior wellbore stability during ope rations.Furthermore,the electric logging interpre tation coincidence rate improved from 68.1% to 89.9%,providing robust te chnical support for high-quality drilling and accurate reservoir evaluation in exploration/appraisal wells.展开更多
To explore the high heat flow anomalies from the Dabie orogenic belt,We have set up 15 Magnetotelluric(MT)stations.The stations have an average spacing of~2 km.Firstly,the phase tensor method is used to analyze MT dat...To explore the high heat flow anomalies from the Dabie orogenic belt,We have set up 15 Magnetotelluric(MT)stations.The stations have an average spacing of~2 km.Firstly,the phase tensor method is used to analyze MT data to estimate the dimensional characteristics of the underground resistivity structure.Then,based on the results of dimensional characteristics analysis,three-dimensional(3D)inversion was performed using ModEM,and a 3D resistivity structure from the surface to a depth of 30 km was obtained.It shows:that there are extensive low resistivity anomalies in the lower crust of the northern margin of the Dabie orogenic belt,which may be partial melting or water-bearing fluid.The high heat flow anomaly in the northern margin of the Dabie orogenic belt may be due to the increase of the background heat flow value caused by the orogenic belt delamination during post-collision,the thinning of the lithosphere and the upwelling of the asthenosphere.展开更多
Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydro...Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydrocarbon accumulation model and enrichment law in the Linhe Depression of the Hetao Basin, NW China. The Hetao Basin mainly experienced three stages of evolution, namely, weak extensional fault depression, strong extensional fault depression and strike-slip transformation, giving rise to four positive structural belts(Jilantai, Shabu, Nalinhu and Xinglong), which are favorable areas for oil and gas accumulation. The two main saline lacustrine source rocks, Lower Cretaceous Guyang Formation and Oligocene Linhe Formation, are characterized by high sulfur content, rich algae, early maturity, early expulsion, and wide oil generation window. The large structural transition belt in the intermountain area around the Hetao Basin controls the formation of large-scale braided river delta deposits, which are characterized by high quartz content(50%-76%), long-term shallow burial and weak compaction, low cement content, and good reservoir properties in delta front sandbody. The burial depth of the effective Paleogene reservoirs is predicted to reach 8000 m. Three hydrocarbon accumulation models, nose-uplift near sag, buried hill surrounding sag, fault nose near source rock, are constructed. The law of hydrocarbon accumulation in the Linhe Depression is finally clarified as follows: near-source around the depression is the foundation, high-quality thick reservoir is the premise, good tectonic setting and trap conditions are the key.展开更多
To prevent hydrogen-induced loss and achieve long-term effective parameters monitoring in harsh downhole environment,we proposed a Fabry-Perot sensor with vacuum sputter deposited carbon coating film,in which we emplo...To prevent hydrogen-induced loss and achieve long-term effective parameters monitoring in harsh downhole environment,we proposed a Fabry-Perot sensor with vacuum sputter deposited carbon coating film,in which we employed a deposition technology with a higher particle kinetic energy,closer substrate adhesion,and denser films,to deposit the coating film on the surface of the quartz capillary glass tube to protect the sensor from corrosion.The sensitivity and accuracy of the Fabry-Perot sensor with carbon film deposition can reach 369 nm/MPa and 0.02%FS,respectively.Meanwhile,the sensor has less hysteresis error and good pressure linearity of more than 0.99999 for repeatable pressure measurement.The downhole practice monitoring data indicated that this fiber-optic sensor exhibited excellent performance and the sputter deposited carbon coating can effectively decrease hydrogen loss.展开更多
基金supported by the National Natural Science Foundation of China (52474024)the National Oil&Gas Major Project of China (2025ZD1403200)the Program for Scientific Research Innovation Team of Young Scholars in Colleges and Universities of Shandong Province"Innovation Team of Deepwater Wellbore Fluids"(2022KJ069)。
文摘In Dagang Oilfield in China,the utilization of the KCl polymer water-based drilling fluid(WBDF) in middeep exploration/appraisal wells presents a challenge in simultaneously optimizing resistivity logging accuracy and wellbore stability.To address this,it is necessary to conduct geology-engineering integration studies.Based on the formation resistivity,an analytical model was developed to assess the impact of KCl concentration in the WBDF on array induction logging response accuracy.The maximum permissible KCl concentration for the target formations was determined,and technical strategies were proposed to maintain wellbore stability at a reduced KCl concentration.After that,considering the inhibitory,encapsulating,and plugging effects,a low-KCl-concentration WBDF was optimized and applied.Model calculations demonstrate that increasing KCl concentration in the WBDF decreases resistivity,thereby reducing logging accuracy.To maintain a logging accu racy of ≥80%,the upper limits for KCl concentration in the WBDF are 4.8%,4.2%,and 3.6% for the 3rd Member of the Dongying Formation,the 1st and 2nd members of the Shahejie Formation,respectively.Cuttings recovery experiments revealed that a minimum KCl concentration of 3% is required to ensure basic shale inhibition.A combination of 3% KCl with 1% polyamine inhibitor yielded cuttings recovery and shale stability index comparable to those achieved with 7% KCl alone,and the shale inhibition performance was further enhanced with the addition of an encapsulator.The optimized WBDF has been successfully deployed in exploration/appraisal wells across multiple blocks within Dagang Oilfield,resulting in superior wellbore stability during ope rations.Furthermore,the electric logging interpre tation coincidence rate improved from 68.1% to 89.9%,providing robust te chnical support for high-quality drilling and accurate reservoir evaluation in exploration/appraisal wells.
基金supported by the National Key Research and Development Program of China(grant no.2023YFF0615101).
文摘To explore the high heat flow anomalies from the Dabie orogenic belt,We have set up 15 Magnetotelluric(MT)stations.The stations have an average spacing of~2 km.Firstly,the phase tensor method is used to analyze MT data to estimate the dimensional characteristics of the underground resistivity structure.Then,based on the results of dimensional characteristics analysis,three-dimensional(3D)inversion was performed using ModEM,and a 3D resistivity structure from the surface to a depth of 30 km was obtained.It shows:that there are extensive low resistivity anomalies in the lower crust of the northern margin of the Dabie orogenic belt,which may be partial melting or water-bearing fluid.The high heat flow anomaly in the northern margin of the Dabie orogenic belt may be due to the increase of the background heat flow value caused by the orogenic belt delamination during post-collision,the thinning of the lithosphere and the upwelling of the asthenosphere.
基金Supported by the PetroChina Key Science and Technology (2021DJ0703)。
文摘Based on paleogeomorphology, drilling and seismic data, this paper systematically studies the structural and sedimentary evolution, source rock characteristics, reservoir characteristics and formation mechanism, hydrocarbon accumulation model and enrichment law in the Linhe Depression of the Hetao Basin, NW China. The Hetao Basin mainly experienced three stages of evolution, namely, weak extensional fault depression, strong extensional fault depression and strike-slip transformation, giving rise to four positive structural belts(Jilantai, Shabu, Nalinhu and Xinglong), which are favorable areas for oil and gas accumulation. The two main saline lacustrine source rocks, Lower Cretaceous Guyang Formation and Oligocene Linhe Formation, are characterized by high sulfur content, rich algae, early maturity, early expulsion, and wide oil generation window. The large structural transition belt in the intermountain area around the Hetao Basin controls the formation of large-scale braided river delta deposits, which are characterized by high quartz content(50%-76%), long-term shallow burial and weak compaction, low cement content, and good reservoir properties in delta front sandbody. The burial depth of the effective Paleogene reservoirs is predicted to reach 8000 m. Three hydrocarbon accumulation models, nose-uplift near sag, buried hill surrounding sag, fault nose near source rock, are constructed. The law of hydrocarbon accumulation in the Linhe Depression is finally clarified as follows: near-source around the depression is the foundation, high-quality thick reservoir is the premise, good tectonic setting and trap conditions are the key.
基金by the National Natural Science Foundation of China(No.61605101)the Natural Fund of Shandong Province(Nos.ZR2021MF127 and ZR2020LLZ010)the Peixin Fund of Qilu University of Technology(No.2022PX074)。
文摘To prevent hydrogen-induced loss and achieve long-term effective parameters monitoring in harsh downhole environment,we proposed a Fabry-Perot sensor with vacuum sputter deposited carbon coating film,in which we employed a deposition technology with a higher particle kinetic energy,closer substrate adhesion,and denser films,to deposit the coating film on the surface of the quartz capillary glass tube to protect the sensor from corrosion.The sensitivity and accuracy of the Fabry-Perot sensor with carbon film deposition can reach 369 nm/MPa and 0.02%FS,respectively.Meanwhile,the sensor has less hysteresis error and good pressure linearity of more than 0.99999 for repeatable pressure measurement.The downhole practice monitoring data indicated that this fiber-optic sensor exhibited excellent performance and the sputter deposited carbon coating can effectively decrease hydrogen loss.
