Theoretical Model for Diagnosing Flow in Mesozoic Formations with a Tight Oil Behavior

The well tested in Cretaceous, by analogy, is presumed that it was a low permeability. Initially the well produced 1,400 bpd of oil, however this volume only lasted 36 hours and gradually well decreased to surface pressures. Bottomhole-pressure sensor indicated it could not restore pressure to initial levels (≈1,000 kg/cm2) and with each closing static pressure (Pws) decreased. The evaluation period lasted 28 days and presented a pressure drop of 400 kg/cm2 with an oil cumulative production of≈11,000 bls. Derivative of this, proceeded to build a well pseudoradial model to evaluate various hypotheses initially raised.

Results show that the case that better reproduces the production-pressure behavior is a model with the following characteristics:

• -Two areas with a contrast of permeabilities: well vicinity (Kx=0.9, Ky=0.3 Kz=1.2mD), K border area well<0.001mD in three directions.
• -Well-reservoir communication with a radius of 150m
• -It was possible to simulate a build up test managing to adjust their behavior of pressure to a dual-porosity model and a closed-homogeneous model.
• -The above justifies the poor communication well-reservoir due to the well geometry
• -It was carried out an exercise by varying well geometry with satisfactory results, allowing you to adapt field exploitation strategy in these reservoirs.