Managing Water and Gas Production Problems in Cantarell: A Giant Carbonate Reservoir in Gulf of Mexico
Authors: Daltaban T. S. , Lozada A. Miguel , Villavicencio P. Antonio , Torres F. Marcos 
Published: June 2009

Located in the Gulf of Mexico, Cantarell Field is the world's second largest carbonate field which has been on production since 1979. After the implementation of Nitrogen injection, peak production has reached to more than 2 million stb/d in early 2000s. Field is now on decline, and currently one of the major challenges is to monitor the advancing fluid levels at wells and control the unexpected fluid breakthroughs. Hence, the design and intelligent well management is key IOR option to Cantarell's late field life management.

This paper presents the results of numerical investigation into the water and gas production problems under different reservoir heterogeneity conditions pertinent to Cantarel Field. For this purpose, some of the typical problem wells have been identified from the production data as well as well registries and their sector models have been extracted from the calibrated full field model. The vertical resolution for these sectors has been increased to be able to track the fluid movements with a greater precision, and heterogeneities at different levels introduced. In addition, the models have utilized dual porosity dual permeability option to particularly handle the matrix contribution to the production anomalies. Because the gas cap continues to advance, the models have been further calibrated to capture this advance more accurately in black oil and compositional modes. The prediction of the models has been controlled by the available analytic techniques to avoid any unrealistic estimates.

Analytic studies of the paper present the ranges of critical flowrates and their sensitivity to some key parameters like realistic permeability ranges of the Cantarel Field, and the location and length of the perforation intervals relative to the fluid levels. The numerical results show the impact of the small scale and large scale heterogeneities including in particular the channeling on the fluid breakthrough problem. The findings and the critical assessment concerning the impact of cavities, their fill including foam; formation of radial barriers to control the advance of the fluid levels around the well; and bottom hole choking to control the gas overproduction problems have also been included into the discussions of this paper. Hence, the possible conditions for the fluid breakthrough have been identified, and some valid recommendations have been made to improve Cantarell Well Management Practices.

Also included in these investigations is the Double Displacement Process modeling (DDP) to identify the amount of oil recovery by the ongoing Nitrogen injection using complex sectors that incorporate radial local grid refinements. The findings have been encouraging in terms of extra oil recovery by the use of this IOR technique. This is due to the specific imbibition/re-imbibition, capillary hysteresis, spreading coefficient ranges and high productivity characteristics of the Cantarell Field that will be discussed in this paper.