Chalco, Alejandro A.¹
(1) Pluspetrol Norte, Lima, Peru

ABSTRACT: Carmen Field: Increasing Reserves and Exploration Potential with Sequence Stratigraphy

Carmen Field, discovered in 1974 at the northern part of the Marañon Basin (Perú), was considered a marginal oilfield in a low relief anticline. In year 2002 an exploratory well drilled over a seismic anomaly to the East of the field encountered a field extension.
Seismic stratigraphy, cores and image logs, identified a depositional control for this extension that increases proven reserves sevenfold, opening the possibility of further extensions and of a new play concept for the Marañon Basin.
Frequency filters applied to Carmen 3D seismic highlighted a “doublet” inside the reflector of Vivian formation, the main reservoir in the basin. While correlating the doublet along 2D and 3D seismic, “clinoforms” were identified. These “clinoforms” form in plan-view two NW-SE trending thickness anomalies (“lobes”).
Wells drilled into the “lobes” encountered a thicker reservoir interval than expected. Core and image log data show drowning surfaces separating a relatively continuous fluvial dominated reservoir in the lower part of Vivian from a more heterogeneous, thinner and laterally discontinuous fluvio-estuarine upper part of Vivian. Integrating all the data and applying sequence stratigraphy techniques, a late LST was assigned to the Vivian Formation.
The seismic data shows different parasequence stacking patterns for each “lobe”. As matter of fact, core and production data from the wells indicates that each parasequence has different reservoir properties.
Mapping the late LST “lobes” revealed additional areas with “stratigraphic” trapping potential waiting for future seismic acquisition and drilling in the area.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.