The typical industry practice for Tension Leg Platform （TLP） design focuses on a conventional short-term design recipe, which assumes that an N-year design environment leads to an N-year response. In the response-ba...The typical industry practice for Tension Leg Platform （TLP） design focuses on a conventional short-term design recipe, which assumes that an N-year design environment leads to an N-year response. In the response-based design method, the TLP is designed to withstand N-year responses rather than respond to N-year environmental conditions. In this paper, we present an overview and a general procedure for the response-based design method and use a case study to compare the critical TLP responses between the two methods. The results of our comparison show that the conventional short-term design method often contains an element of conservatism and that the response-based design method can reduce the design conditions and thereby achieve cost savings.展开更多
Modern opticai theory has shown that the far field or Fraunbofer diffraction equipment is identical to the Fourier spectral analyzer. In the Fourier speetral analyzer the Fourier spectra or the Fraunhofer diffaction p...Modern opticai theory has shown that the far field or Fraunbofer diffraction equipment is identical to the Fourier spectral analyzer. In the Fourier speetral analyzer the Fourier spectra or the Fraunhofer diffaction pattern of a graph is formed on the back focal plane when a laser beam is directed on the graph lying on the front foeal plane ; the Fourier spectra of the graph is also subjected to change during the deformation of the graph. Through analyzing the change of Fourier spectra the deformation of the graph can be obtained. A few years ago,based on the above principles the authors proposed a new technique of strain measurement by laser spectral analysis. Demonstration and discussion will be made in detail in this paper.展开更多
I present an algorithm that uses cross-dipole wireline data only in order to estimate the HTI stiffness tensor for sandstone formations under in-situ asymmetric lateral (azimuthal) stress conditions.The algorithm is b...I present an algorithm that uses cross-dipole wireline data only in order to estimate the HTI stiffness tensor for sandstone formations under in-situ asymmetric lateral (azimuthal) stress conditions.The algorithm is based on the generalization of terms "excess compliance" and "fracture weakness" developed within the linear slip interface theory for fractured rocks and is applied here to describe the effect of grain contacts in loose sandstones.I introduce the term "plane of weakness" being oriented (aligned) orthogonal to theminimal horizontal principal stress direction in order to describe the overall effective weakness of sandstone caused by the different principal stresses.For the quantification of this phenomenon I use the anisotropic Gassmann model.As a result I am able to calculate a HTI stiffness tensor for the interval length of a saturated sandstone formation and the respective Thomsen's parameters.The input data required for these calculations have to be provided by wireline logging and will consist of porosity,density,P-wave velocity,fast and slow shear wave velocities and oil-water saturation ratio.The algorithm in its current form is applicable to sandstone reservoirs only.Its limitation is based on two assumptions,which state that all the measured anisotropy is induced by the present stress in sandstone and that the unstressed sandstone would be nearly isotropic.From a technical viewpoint this algorithm can be implemented fairly easily in data acquisition and interpretation software relying on correct estimation of anisotropy parameters.It is also cheap because it does not require any additional measurements apart from the cross-dipole logging.展开更多
文摘The typical industry practice for Tension Leg Platform （TLP） design focuses on a conventional short-term design recipe, which assumes that an N-year design environment leads to an N-year response. In the response-based design method, the TLP is designed to withstand N-year responses rather than respond to N-year environmental conditions. In this paper, we present an overview and a general procedure for the response-based design method and use a case study to compare the critical TLP responses between the two methods. The results of our comparison show that the conventional short-term design method often contains an element of conservatism and that the response-based design method can reduce the design conditions and thereby achieve cost savings.
文摘Modern opticai theory has shown that the far field or Fraunbofer diffraction equipment is identical to the Fourier spectral analyzer. In the Fourier speetral analyzer the Fourier spectra or the Fraunhofer diffaction pattern of a graph is formed on the back focal plane when a laser beam is directed on the graph lying on the front foeal plane ; the Fourier spectra of the graph is also subjected to change during the deformation of the graph. Through analyzing the change of Fourier spectra the deformation of the graph can be obtained. A few years ago,based on the above principles the authors proposed a new technique of strain measurement by laser spectral analysis. Demonstration and discussion will be made in detail in this paper.
基金supported by the CRGC Consortium in Australiathe National S&T Major Project of China (Grant No. 2008ZX05008- 006-034)the National Natural Science Foundation of China (Grant No. 40774099)
文摘I present an algorithm that uses cross-dipole wireline data only in order to estimate the HTI stiffness tensor for sandstone formations under in-situ asymmetric lateral (azimuthal) stress conditions.The algorithm is based on the generalization of terms "excess compliance" and "fracture weakness" developed within the linear slip interface theory for fractured rocks and is applied here to describe the effect of grain contacts in loose sandstones.I introduce the term "plane of weakness" being oriented (aligned) orthogonal to theminimal horizontal principal stress direction in order to describe the overall effective weakness of sandstone caused by the different principal stresses.For the quantification of this phenomenon I use the anisotropic Gassmann model.As a result I am able to calculate a HTI stiffness tensor for the interval length of a saturated sandstone formation and the respective Thomsen's parameters.The input data required for these calculations have to be provided by wireline logging and will consist of porosity,density,P-wave velocity,fast and slow shear wave velocities and oil-water saturation ratio.The algorithm in its current form is applicable to sandstone reservoirs only.Its limitation is based on two assumptions,which state that all the measured anisotropy is induced by the present stress in sandstone and that the unstressed sandstone would be nearly isotropic.From a technical viewpoint this algorithm can be implemented fairly easily in data acquisition and interpretation software relying on correct estimation of anisotropy parameters.It is also cheap because it does not require any additional measurements apart from the cross-dipole logging.
