A numerical model and transmission characteristic analysis of DPSK （differential phase shift keying） pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry,...A numerical model and transmission characteristic analysis of DPSK （differential phase shift keying） pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry, a logical control signal is built from a Gate function sequence according to the binary symbols of transmitted data and a phase-shift function is obtained by integrating the logical control signal. A mathematical model of the DPSK pressure signal is built based on principles of communications by modulating carrier phase with the phase-shift function and a numerical simulation of the pressure wave is implemented with the mathematical model by MATLAB programming. Considering drillpipe pressure and drilling fluid temperature profile along drillpipes, the drillpipe of a vertical well is divided into a number of sections. With water-based drilling fluids, the impacts of travel distance, carrier frequency, drillpipe size, and drilling fluids on the signal transmission were studied by signal transmission characteristic analysis for all the sections. Numerical calculation results indicate that the influences of the viscosity of drilling fluids and volume fraction of gas in drilling fluids on the DPSK signal transmission are more notable than the others and the signal will distort in waveform with differential attenuations of the signal frequent component.展开更多
At present,the MWD systems continuous wave mud pulse telemetry transmit is not faster than 1or 2bits/s from deep wells containing highly attenuative mud,because positive pulsers create strong signals but large axial f...At present,the MWD systems continuous wave mud pulse telemetry transmit is not faster than 1or 2bits/s from deep wells containing highly attenuative mud,because positive pulsers create strong signals but large axial flow forces impede fast reciprocation while mud sirens provide high data rates without higher signal strength.A high-data-rate system providing 10bits/s and operable up to30 000 ft is described,which creates strong source signals by using downhole constructive wave interference in two novel ways.Telemetry schemes,frequencies and pulser locations in the MWD drill collar are selected for positive wave phasing,and sirens-in-series are used to create additive signals——both without incurring power and erosion penalties.The positions normally occupied by pulsers and turbines are reversed to minimize times required for constructive interference and modulation.A system design approach is undertaken,e.g.,strong source signals are augmented with new multiple-transducer surface signal processing methods to remove mudpump noise and signal reflections at both pump and desurger,and mud,bottomhole assembly and drill pipe properties,to the extent possible in practice,are controlled to reduce signal attenuation.The results of detailed acoustic modeling in realistic drilling telemetry channels are described,and short and long wind tunnels for signal strength,torque,erosion and jamming testing,and telemetry and signal processing evaluation,respectively,are introduced.Special scaling methods are developed to extrapolate cost-effective wind tunnel test results to real muds flowing at any downhole speed.New siren concept prototype hardware and also typical acoustic test results are also given.展开更多
On the basis of reviewing the development history of drilling engineering technology over a century, this paper describes the technical and scientific background of downhole control engineering, discusses its basic is...On the basis of reviewing the development history of drilling engineering technology over a century, this paper describes the technical and scientific background of downhole control engineering, discusses its basic issues, discipline frame and main study contents, introduces the research progress of downhole control engineering in China over the past 30 years, and envisions the development direction of downhole control engineering in the future. The author proposed the study subject of well trajectory control theory and technology in 1988, and further proposed the concept of downhole control engineering in 1993. Downhole control engineering is a discipline branch, which applies the perspectives and methods of engineering control theory to solve downhole engineering control issues in oil and gas wells; meanwhile, it is an application technology field with interdisciplinarity. Downhole control engineering consists of four main aspects; primarily, investigations about dynamics of downhole system and analysis methods of control signals; secondly, designs of downhole control mechanisms and systems, research of downhole parameters collections and transmission techniques; thirdly, development of downhole control engineering products; fourthly, development of experimental methods and the laboratories. Over the past 30 years, the author and his research group have achieved a number of progress and accomplishments in the four aspects mentioned above. As a research field and a disciplinary branch of oil and gas engineering, downhole control engineering is stepping into a broader and deeper horizon.展开更多
基金supported by High Technology Research and Development Program of China(No.2006AA06A101).
文摘A numerical model and transmission characteristic analysis of DPSK （differential phase shift keying） pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry, a logical control signal is built from a Gate function sequence according to the binary symbols of transmitted data and a phase-shift function is obtained by integrating the logical control signal. A mathematical model of the DPSK pressure signal is built based on principles of communications by modulating carrier phase with the phase-shift function and a numerical simulation of the pressure wave is implemented with the mathematical model by MATLAB programming. Considering drillpipe pressure and drilling fluid temperature profile along drillpipes, the drillpipe of a vertical well is divided into a number of sections. With water-based drilling fluids, the impacts of travel distance, carrier frequency, drillpipe size, and drilling fluids on the signal transmission were studied by signal transmission characteristic analysis for all the sections. Numerical calculation results indicate that the influences of the viscosity of drilling fluids and volume fraction of gas in drilling fluids on the DPSK signal transmission are more notable than the others and the signal will distort in waveform with differential attenuations of the signal frequent component.
文摘At present,the MWD systems continuous wave mud pulse telemetry transmit is not faster than 1or 2bits/s from deep wells containing highly attenuative mud,because positive pulsers create strong signals but large axial flow forces impede fast reciprocation while mud sirens provide high data rates without higher signal strength.A high-data-rate system providing 10bits/s and operable up to30 000 ft is described,which creates strong source signals by using downhole constructive wave interference in two novel ways.Telemetry schemes,frequencies and pulser locations in the MWD drill collar are selected for positive wave phasing,and sirens-in-series are used to create additive signals——both without incurring power and erosion penalties.The positions normally occupied by pulsers and turbines are reversed to minimize times required for constructive interference and modulation.A system design approach is undertaken,e.g.,strong source signals are augmented with new multiple-transducer surface signal processing methods to remove mudpump noise and signal reflections at both pump and desurger,and mud,bottomhole assembly and drill pipe properties,to the extent possible in practice,are controlled to reduce signal attenuation.The results of detailed acoustic modeling in realistic drilling telemetry channels are described,and short and long wind tunnels for signal strength,torque,erosion and jamming testing,and telemetry and signal processing evaluation,respectively,are introduced.Special scaling methods are developed to extrapolate cost-effective wind tunnel test results to real muds flowing at any downhole speed.New siren concept prototype hardware and also typical acoustic test results are also given.
文摘On the basis of reviewing the development history of drilling engineering technology over a century, this paper describes the technical and scientific background of downhole control engineering, discusses its basic issues, discipline frame and main study contents, introduces the research progress of downhole control engineering in China over the past 30 years, and envisions the development direction of downhole control engineering in the future. The author proposed the study subject of well trajectory control theory and technology in 1988, and further proposed the concept of downhole control engineering in 1993. Downhole control engineering is a discipline branch, which applies the perspectives and methods of engineering control theory to solve downhole engineering control issues in oil and gas wells; meanwhile, it is an application technology field with interdisciplinarity. Downhole control engineering consists of four main aspects; primarily, investigations about dynamics of downhole system and analysis methods of control signals; secondly, designs of downhole control mechanisms and systems, research of downhole parameters collections and transmission techniques; thirdly, development of downhole control engineering products; fourthly, development of experimental methods and the laboratories. Over the past 30 years, the author and his research group have achieved a number of progress and accomplishments in the four aspects mentioned above. As a research field and a disciplinary branch of oil and gas engineering, downhole control engineering is stepping into a broader and deeper horizon.
