Barnes, Simon (PGS) | van Borselen, Roald (PGS) | Salazar, Humberto (Pemex Exploration and Production) | Vàzquez, Alfredo (Pemex Exploration and Production) | Ronzón, Israel (Pemex Exploration and Production) | Martinez, Ruben (PGS)
A processing strategy for the 3D prediction and subsequent elimination of long period surface-related multiples (SRME) contaminating a 3D sparse non-orthogonal land seismic data is presented. A comparison is made between 1D and 3D multiple prediction using the Surface-related Multiple Elimination (SRME) method, showing that significant improvements can be obtained by taking into account the full 3D complexity of the subsurface. Multidimensional Fourier regularization has been proven to be a critical component of the pre-conditioning of the data applied prior to the multiple prediction and subtraction.
Matsuzawa, Shinichi (Japan Oil, Gas and Metals National Corporation) | Konishi, Yusaku (Japan Oil, Gas and Metals National Corporation) | Nishizuka, Tomohisa (Japan Oil, Gas and Metals National Corporation) | Aldana, Arturo Perez (Pemex Exploration and Production) | Hernandez, Efrain Mendez (Pemex Exploration and Production) | Ortiz, Manuel A. Mercado (Pemex Exploration and Production) | Fernandez, Jose Alberto Santana (Pemex Exploration and Production) | Chaboudy, Louis R. (Veritas Exploration Services) | Gonzalez, Hansel (Veritas Exploration Services)
A recent trend in reservoir studies is the integration of petrophysical geological and geophysical information in high-resolution reservoir models. Success in integrated reservoir characterization depends on identifying seismic and petrophysical attributes that are well correlated to the properties being modeled e.g., lithofacies, porosity and fluid type. This study employed integrated petrophysical analysis, well-based rock property study, acoustic and elastic seismic inversions, AVO modeling and attribute generation to characterize Oligocene gas reservoirs in the Cuitlahuac Field in the Burgos Basin of northeastern Mexico. Cuitlahuac Field has produced over 320 Bcf since its discovery in 1972. Current daily production is 28 MMcfd. Production is from thin-bedded Tertiary fluvio-deltaic clastics with complex reservoir geometry. Of nine well-based seismic attributes generated from the petrophycial logs (Possion's Ratio, Acoustic Impedance, Shear Impedance, Lambda, Mu, Bulk Modulus, Lambda-Rho, Mu-Rho and Vp/Vs), acoustic impedance (AI) most effectively discriminates sandstone from shale - but only in the shallower section. Amplitude versus offset (AVO) analysis shows Class I response in the shallower section and Class II response in the deeper section. On the other hand, fluid substitution study shows that Mu-Rho and Lambda-Rho are good discriminators for both lithology and fluid type. To capture detail in the thin gas reservoirs, high-resolution stochastic inversion was performed on the 3D seismic volume. The resulting acoustic and shear impedance volumes show good correlation with well log data. The attributes Lambda-Rho and Mu-Rho were calculated from the acoustic impedance (Ip) and shear impedance (Is) volumes. The seismic-derived Lambda-Rho and fluid type at each well were integrated using sequential indicator simulation with collocated cokriging to obtain a reservoir model.
Robinson, B.M. (S.A. Holditch & Associates) | Rascon, Austreberto Rios (Pemex Exploration and Production) | Hernandez, Crescenciano Perez (Pemex Exploration and Production) | Sanchez Bujanos, Juan M. (Pemex Exploration and Production)
Several studies have been performed recently that have focused on reevaluating the original fracture treatment designs performed in various low permeability gas fields in the Burgos Basin of northern Mexico. The primary goal of these studies was to determine if the fracture treatments were achieving optimal stimulation of the reservoirs. Results of this work have indicated that the propped fracture half-lengths achieved in the past are approximately 40% to 50% of the original designed half-lengths. The main reason for the shorter fracture lengths is that the created fracture heights were greater than expected.
The studies have provided better descriptions of individual reservoir properties and vertical stress profiles. These results are now being used in both reservoir and fracture models to design more optimal fracture treatments. These new fracture treatment designs have increased production from 50% to 300% over previous fracture designs.