Published: 01/23/2015
Published: 01/23/2015
PEMEX applied a fracturing treatment in one of its sandstone fields in southern Mexico, increasing the oil production for each well by 800 bbl/d on average. However, because field development was initially planned without fracturing, well spacing was tight with a pattern random (about 656 ft [200 m]).Furthermore, fracturing interference had occurred for some of the wells.
No data was available for the wells with interference to measure the minimum stress direction, although the estimated direction of the maximum horizontal stress was to NE 50°, according to the location of two wells that interfered with each other. In addition, because the field is subjected to salt intrusion from both west and east sides, the direction of the maximum horizontal stress may rotate.
PEMEX requested the Sonic Scanner platform, which transmits radial acoustic waves that can be measured over a broad frequency band compared with conventional sonic tools. It is built with upper and a lower monopole transmitters and a far monopole transmitter; signals are received by 13 receiver stations composed of 8 receivers located radially. Thus, the architecture permits compressional and shear radial profiling to be obtained in addition to the formation anisotropy, which enables estimating the principal stress orientations, magnitude, and rock mechanical properties in 3D.
Fracture modeling generated using Mangrove stimulation design showed that the two fractured wells were parallel and not communicating directly with one another; approximately 15° was estimated between the fracture plane and the well’s orientation between each. The preliminary fracturing design was readjusted to create a fracture half the length of the original design. In addition, the estimation of the Young’s modulus value helped the operator make the decision to deploy the HiWAY technique for the first time in southern Mexico.
The preliminary geomechanical model estimated from the Sonic Scanner platform’s data was adjusted in the FracCADE software to obtain a match between the simulated and the field treating pressure, decreasing the predicted values by 6%.
In addition, the offset fractured well located at 656 ft [200 m] did not show any change in wellhead pressure during the fracturing treatment, and its production performance remained the same.
It was important to exactly estimate the propagation of the hydraulic fracture, because rotating the in situ stress direction by as little as 15° could have led to results similar to the previous interference cases. An increase in oil production to a rate of 1,430 bbl/d—more than any other well in the field—was attributed to the HiWAY technique.
PEMEX considered the application of the Sonic Scanner platform as successful in the decision process for selection of the fracturing method—the HiWAY technique—which was more cost effective when compared with traditional fracturing methods.
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