Using Microseismic Monitoring to Enhance Field Development Strategy and Production in a Colombian Mature Field
Microseismic events induced by hydraulic fracturing were monitored in a treatment well, located in a mature field in Eastern Llanos basin, Colombia, for the first time in Latin America. The field development strategy has been focused on the production of three main reservoirs. The upper reservoir, currently in production, is characterized by sandstone-shale interbedding that divide the reservoir into five lithostratigraphic units. An alternative considered to develop this reservoir consists of drilling highly deviated wells into the upper lithostratigraphic units and connect them with the lower ones throughout hydraulic fracturing. In order to evaluate the viability of this alternative, an abandoned vertical well was selected to carry out microseismic monitoring immediately after the culmination of one Minifrac stage, and later obtain information about geometry and orientation of the stimulated zone. This data is fundamental for reservoir management optimization. The acquired microseismic data from the treatment well was processed using the STA/LTA ratio method. This detects microseismic events and differentiates them from background noise. In order to define the background noise level, the data recording started a couple of hours before the main monitoring period. Since the pressure of the pumped fluid is not enough to keep the fractures open after the Minifrac ends, most of the recorded data is related to fracture closure events. A 3D image of induced microseismic events was obtained from the monitoring process. From this data, the geometry and orientation of the stimulated zone was assessed and showed a preferential azimuth of 136° as well as the following dimensions: 310 ft length, 30 ft width and 125 ft height, approximately. Moreover, the connectivity of the three lower units through hydraulic fracturing was confirmed and the regional maximum horizontal stress direction corroborated. Microseismic monitoring technology effectively minimized rig time and well intervention costs in this well and improved hydrocarbon production and field development management.
AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014