Print this pageFirst Microseismic Acquisition in South America — Lajas Tight Gas Project - Neuquén, Argentina
Buhler, Gustavo M.1
d'Huteau, Emmanuel1
Peñacorada, 
Fabio
1
Exler, Ariel2
During 2008, a pilot drilling and completion project was executed in the tight sands of the Lajas Formation (Dogger), Neuquén basin, Argentina. In the Cupen Mahuida area of the Loma La Lata economic unit, this formation has an average total thickness of 860 m and is composed of a sequence of shallow marine to fluvial sandstones and siltstones. The reservoir has an average permeability of 0.01 mD and porosity of 7%. In these sandstones the existence of considerable volumes of gas has been proven which thus far have not been exploited.
To obtain an economic level of production this reservoir must be hydraulically fractured. As the growth of a fracture cannot be accurately predicted using the geomechanical parameters estimated from logs, the project included the monitoring of some of the stimulations by microseismic survey acquisition. The objective was to measure fracture geometry so as to determine the effectiveness of the treatment and to better evaluate the productivity of the fracture.
The microseismic survey acquisition, which involved one of the pilot wells and a suitably located monitor well was performed in July, 2008. Despite some restrictions with respect to the vertical positioning of the geophones in the monitor well, it was possible to record microseismic events in 5 out of 6 fracture treatments, with good quality data being gathered during stages 4 to 6.
The integration of microseismic, pressure, 3D seismic, petrophysic, image log, and production log data allows us to interpret not only the behaviour of different fracture techniques (single point, limited entry, hybrid frac,…) but also enabled the detection of the interaction between the fracture and geological features. The role of a nearby fault as a barrier to fracture growth and the presence of natural fractures can be inferred from the data and we were also able to verify the maximum horizontal stress direction. The data gathered has proven valuable and is contributing to our understanding of the drainage behaviour through dynamic reservoir simulations.
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil