Renewed Exploration Interest in the Mature Basal Tena / M1 Sandstone Play – Kupi-Wanke Area, Block 14, Oriente Basin, Ecuador

Abstract

Abstract

Oil was discovered in the early 1990's in the Basal Tena / M1 sands which occur at the Upper Cretaceous Unconformity in the Kupi-Wanke area of Block 14, Oriente Basin, Ecuador. Early successful wells all produced from thin sands ranging from about 10 to 20 feet thick; below the resolution of the 2D seismic data. It was also impossible to interpret if the sands were Upper Cretaceous M1 below the unconformity or Basal Tena sands above the unconformity. Unsuccessful wells either had thicker, water bearing M1 sands, thin poorly developed sands, or no sand deposition.

Successful wells have had good production from thin sands with low water cuts over a prolonged period of time; and together with the widespread distribution of the oil wells, and the lack of good structural closures, suggested a regional, stratigraphically controlled oil trapping system. The best example of this is the Kupi 1 well which has produced over 3.7 mmbbls of oil over a 21 year period and is still producing about 460 bopd with less than 50% water cut; an uncommon production situation in the Oriente Basin. Two appraisal wells drilled after Kupi 1 were both unsuccessful, one with no sand and one with only very thin, wet sands.

The geological model for the BT/M1 oil play has developed over time to where it is currently believed that the BT/M1 is a regional stratigraphically controlled play where most prolific wells have thin sands of less than 20 feet that drain large areas. The main M1 was deposited westwardly forming an expansive sand. The Kupi-Wanke area occurs in the basin syncline where the western limb of the syncline is warped upwards to the west due to Andes mountains uplift. This upward warping caused erosion of the main M1 sands and deposition of reworked M1 as thin sand bodies which currently dip upwards to the west. The thin oil-bearing sands benefit from being distant from the main M1 aquifer in the east, resulting in prolonged lower water cuts.

The biggest challenge in pursuing potential in the BT/M1 stratigraphic play is the seismic mapping of the thin sands of 2-3 milliseconds which are below normal seismic resolution. The company has undertaken in the past a number of research studies with mixed success, to try and find the solution to map the sand distribution based on special processed seismic volumes. Recent work has increased the confidence in defining the sand distribution and orientation.

In 2016, it is hoped to drill new locations to confirm the new mapping and to open up new development areas to exploit this potentially prolific, but challenging play.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016