The Journey Towards Discovery of an Unconventional Play in the Middle Magdalena Valley Basin, Colombia, South America
Molina, Carlos1; Loosveld, Ramon; Veldkamp, Jaap; Calvache, Jorge A.; Campos, Henry; Prada, Adriana; and Davis, James
The Middle Magdalena Valley Basin (MMVB) is a prolific hydrocarbon province in northwest Colombia with early exploration activity dating back to the 1920’s. Traditionally, exploration in the MMVB has been limited to structural traps with reservoirs in Tertiary fluvial sands and occasionally, structural traps with fractured Cretaceous carbonates. The hydrocarbon source rocks for these oil fields are Cretaceous.
The emerging unconventional oil play in the MMVB relies on two source rock sequences, the La Luna Formation and the stratigraphically deeper Basal Carbonates, which together add up to about 760 m (2500 ft) in thickness. The La Luna and Basal Carbonates packages are a mixture of carbonaceous shales and limestones of very low matrix permeability, containing Type-II organic matter and TOC ranging from 4-6% and 1-2%, respectively. Shell took an early position in the play, obtaining three contiguous blocks in the MMVB. In Shell’s leases, these two marine sequences are continuous and structurally simple. Co-locating areas with a combination of economically favorable drilling depths and the right oil maturity level yields two sweetspots.
Shell has acquired 475 km of 2D seismic and 35 km² of 3D seismic. The latter will aid in the positioning of horizontal wells and will also allow us to evaluate seismic anisotropy. We are now about to embark on 3 exploratory wells. Two of those will target both the La Luna and Basal Carbonates packages and one will target only a deeper La Luna Formation. Data from the wells will include 275 m (900 ft) core and full suites of logs. The purpose of this Phase 1 exploration program is to prove the presence of a working unconventional system. In addition, Shell is conducting geologic studies which combine field sampling and mapping, legacy core descriptions, and geochemical, biostratigraphic, and mineralogical analyses for key legacy wells.
Operational challenges to overcome during this initial phase of exploration are the necessity of river transport-operations, the presence of flood-prone areas, seasonal restriction of operational windows, a lack of road infrastructure, and an immature fraccing industry.
Shell has developed an approach that integrates the subsurface technical work with mitigation plans for the non-technical risks. Having a good understanding of the nonexclusive nature between the technical and non-technical risks is critical for the successful exploration and development of this unconventional play.
AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013