La Luna Shale in Colombia is the main source rock in the Middle Magdalena Valley (MMV) and the Catatumbo Basins. La Luna shale is a high-quality source rock and its potential has been investigated by several authors. This paper presents geological, geochemical, and petrophysical description of La Luna shale with the dual objective of (1) utilizing CO2 for improving oil recovery through Huff-n-Puff (HnP) gas injection, and (2) storing CO2 safely and without leaks.
The overall approach includes verifying that geologic fluid containment exists in the shale reservoir. The present work shows that this is indeed the case in La Luna shale. Geologic containment is valuable as it permits maximizing oil recovery from La Luna shale and safe storage of CO2 with negligible possibilities of fluid leakage, thus providing a valuable contribution to solve problems related to climate change. Consequently, the procedure described in this paper conforms well to CCUS: Carbon capture, utilization and storage of CO2.
The Eagle Ford shale in Texas is a good analog of La Luna shale. In both reservoirs, sedimentation and development of the source rock start at about the same time in the late Cretaceous, about 93 million years ago. It is not surprising then that in both Eagle Ford and La Luna shales, oil, condensate and natural gas are in the same location where they were generated, gas is at the bottom, condensate in the middle and crude oil at the top of the structure. Thus, the hydrocarbon fluids have been upside down or inverted position through millions of years. This constitutes geologic containment.
The paper describes the following activities once geologic containment is established: (1) drill a pilot horizontal well (HW), (2) stimulate the HW with multi-stage hydraulic fractures and investigate the environmental impact (if the pilot is successful, drill another pilot(s)), (3) produce oil by primary means for a maximum of 2-3 years, (4) implement HnP CO2 injection, (5) store the CO2 in the shale reservoir once the HnP reaches economic limit. Regular pressure monitoring throughout the life of the HnP project guarantees the lack of leaks, a major concern when CO2 is stored in other types of depleted reservoirs or aquifers.
The novelty of the paper is demonstrating geologic containment in La Luna shale in both the MMV and Catatumbo Basins of Colombia. This provides the basis for implementing CCUS. The geological, geochemical and petrophysical description allow to construct a simulation model to investigate primary recovery as well as EOR by HnP CO2 injection. CO2 can be stored safely, without leaks, in the shale reservoir once the HnP project reaches economic limit.