The high resolution 3D nonlinear integrated inversion method is based on nonlinear theory. Under layer control, the log data from several wells （or all wells） in the study area and seismic trace data adjacent to the...The high resolution 3D nonlinear integrated inversion method is based on nonlinear theory. Under layer control, the log data from several wells （or all wells） in the study area and seismic trace data adjacent to the wells are input to a network with multiple inputs and outputs and are integratedly trained to obtain an adaptive weight function of the entire study area. Integrated nonlinear mapping relationships are built and updated by the lateral and vertical geologic variations of the reservoirs. Therefore, the inversion process and its inversion results can be constrained and controlled and a stable seismic inversion section with high resolution with velocity inversion, impedance inversion, and density inversion sections, can be gained. Good geologic effects have been obtained in model computation tests and real data processing, which verified that this method has high precision, good practicality, and can be used for quantitative reservoir analysis.展开更多
B and C sands of the Lower Goru Formation of Cretaceous are proven reservoirs in different parts of the Middle and Lower Indus Basin,Pakistan.Most of the discoveries in this basin have been made in structural traps.Ho...B and C sands of the Lower Goru Formation of Cretaceous are proven reservoirs in different parts of the Middle and Lower Indus Basin,Pakistan.Most of the discoveries in this basin have been made in structural traps.However,in Sawan gas field;structural inversion,deep burial depth and heterogeneity of reservoir intervals make it difficult to demarcate the sweetness zones through conventional seismic analysis.In this work,different data sets have been integrated through constrained sparse spike inversion to mark sweetness zones in B and C sands of this formation.C sand contains four sweetness zones;the main sweetness zone is located towards the east while three subtle sweetness zones were identified towards the west of Sawan fault.The location of producing and nonproducing wells within the sweetness and outside of sweetness zones confirms the credibility of this work.B sand includes three sweetness zones located towards the west of Sawan fault.Moreover,inverted porosity results not only show good agreement with the porosity log of blind well(Sawan-02)but also show good matching with the core porosities.Hence integration of different data sets leads to demarcate the accurate location,size and extent of the sweetness zones.展开更多
Let (P, Q) be a C1 vector field defined in an open subset U IR2. We call inverse integrating factor a C1 solution V(x, y) of the equation . In previous works it has been shown that this function plays an important ro...Let (P, Q) be a C1 vector field defined in an open subset U IR2. We call inverse integrating factor a C1 solution V(x, y) of the equation . In previous works it has been shown that this function plays an important role in the problem of the center and in the determination of limit cycles. In this paper we obtain necessary conditions for a polynomial vector field (P, Q) to have a polynomial inverse integrating factor.展开更多
We characterize the complex differential equations of the form dy/dx=a_(n)(x)y^)n_+a_(n-1)(x)y^(n-1)+…+a_(1)(x)y+a_(0)(x) where a_(j)(x) are meromorphic functions in the variable x for j = 0,..., n that admit either ...We characterize the complex differential equations of the form dy/dx=a_(n)(x)y^)n_+a_(n-1)(x)y^(n-1)+…+a_(1)(x)y+a_(0)(x) where a_(j)(x) are meromorphic functions in the variable x for j = 0,..., n that admit either a Weierstrass first integral or a Weierstrass inverse integrating factor.展开更多
基金supported by the Key Project of the National Natural Scientific Foundation(Grant No.40839909)
文摘The high resolution 3D nonlinear integrated inversion method is based on nonlinear theory. Under layer control, the log data from several wells （or all wells） in the study area and seismic trace data adjacent to the wells are input to a network with multiple inputs and outputs and are integratedly trained to obtain an adaptive weight function of the entire study area. Integrated nonlinear mapping relationships are built and updated by the lateral and vertical geologic variations of the reservoirs. Therefore, the inversion process and its inversion results can be constrained and controlled and a stable seismic inversion section with high resolution with velocity inversion, impedance inversion, and density inversion sections, can be gained. Good geologic effects have been obtained in model computation tests and real data processing, which verified that this method has high precision, good practicality, and can be used for quantitative reservoir analysis.
文摘B and C sands of the Lower Goru Formation of Cretaceous are proven reservoirs in different parts of the Middle and Lower Indus Basin,Pakistan.Most of the discoveries in this basin have been made in structural traps.However,in Sawan gas field;structural inversion,deep burial depth and heterogeneity of reservoir intervals make it difficult to demarcate the sweetness zones through conventional seismic analysis.In this work,different data sets have been integrated through constrained sparse spike inversion to mark sweetness zones in B and C sands of this formation.C sand contains four sweetness zones;the main sweetness zone is located towards the east while three subtle sweetness zones were identified towards the west of Sawan fault.The location of producing and nonproducing wells within the sweetness and outside of sweetness zones confirms the credibility of this work.B sand includes three sweetness zones located towards the west of Sawan fault.Moreover,inverted porosity results not only show good agreement with the porosity log of blind well(Sawan-02)but also show good matching with the core porosities.Hence integration of different data sets leads to demarcate the accurate location,size and extent of the sweetness zones.
基金the DGICYT grant, number PB96-1153 The third author is partially supported by the University of Lleida Project P98-207.
文摘Let (P, Q) be a C1 vector field defined in an open subset U IR2. We call inverse integrating factor a C1 solution V(x, y) of the equation . In previous works it has been shown that this function plays an important role in the problem of the center and in the determination of limit cycles. In this paper we obtain necessary conditions for a polynomial vector field (P, Q) to have a polynomial inverse integrating factor.
基金partially supported by the Ministerio de Economia,Industria y Competitividad,Agencia Estatal de Investigacion grant MTM2016-77278-P (FEDER)the Agència de Gestio d’Ajuts Universitaris i de Recerca grant 2017SGR1617+1 种基金the H2020 European Research Council grant MSCA-RISE-2017-777911partially supported by FCT/Portugal through the pro ject UID/MAT/04459/2013。
文摘We characterize the complex differential equations of the form dy/dx=a_(n)(x)y^)n_+a_(n-1)(x)y^(n-1)+…+a_(1)(x)y+a_(0)(x) where a_(j)(x) are meromorphic functions in the variable x for j = 0,..., n that admit either a Weierstrass first integral or a Weierstrass inverse integrating factor.
