Abstract
The field subject of this paper is located in the southern Mexico, 34 km North of Villahermosa, Tabasco. Oil exploitation targets the Cretaceous and Jurassic formations (4500 mts a 5200 mts TVD). The 12 ¼" section of these wells must be drilled through a high pressure tertiary salt diapir which historically has been a high NPT generator due to high pressure salt water kicks and OBM contamination. Drilling strategy is usually oriented to the use of high density inverse emulsion mud with densities normally ranging between 1.95 to 2.27 SG (16.2 to 18.9 ppg). High density mud causes losses in the interfaces above and below the salt diapir and in some cases losses while drilling the salt diapir due to sand intercalations. A close analysis of the offset wells identified the MPD as a possible solution to mitigate the risks confronted in the section. This document describes the first application of the automated choke MPD system in Mexico, in a Sen well, and how the use of automated choke MPD system allowed drilling the section with no major operational events such as influxes, losses, stuck pipe or salt water contamination of OBM. The system helped detecting micro influxes giving tangible added value to this challenging narrow mud window hole section. As a result 938 meters of salt were drilled in only 11 days while field average is around 30 days.
