8/15/2019 Briefing SPE69718

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 A Coupled Reservoir-Geomechanics Model and Applications to Wellbore

Stability and Sand Prediction

When oil is produced from poorly cemented formations sand production and openhole collapse occur making them harmful problems that cost petroleum industry

more than 500 million US Dollars, this digit is an estimate due to many problemsabout wellbore stability that still remain not adequately defined and evaluated,therefore it is important to define accurately the onset of sand production, in that

way many costs will be reduced.

In consequence, deformation and plastic yielding mechanisms are studied in the

present research, also are included drag forces by the fluid in flux and in situ-stress that conduct to a major sand production. Due to these factors, a coupled

reservoir-geomechanics model is used, which is defined based on a stress-straincombined criteria, it’s also necessary the coupling to a multiphase flow which isgenerally present during underbalanced conditions and in production zones.

Through this model the effects of capillary pressure, wetting phase change,relative permeability and pore volume can be modeled.

The inefficient evaluation of wellbore stability through stresses calculations andstrength measurements is due to both parameters cannot be obtained with great

confidence, stress calculations can only be determined indirectly and strength isa function of many factors like geometry, saturation, grain size and sample size.

Hence to determine the onset of sand production a critical effective strain isneeded. The model must be integrated by other important factor like reservoir

mobility where permeability and viscosity influence sand production, the bottomhole pressure decline rate indicates how easily the formation collapses during

production. The integration of reservoir and geomechanics parameter can leadto minimize production problems and wellbore stabili ty if it is adequately appliedto the field requirements.

REFERENCES

Yarlong Wang, SPE, Petro-Geotech Inc. and Baoping Lu, China New Star

Company. SPE 69718, A Coupled Reservoir-Geomechanics Model and

 Applications to Wellbore Stability and Sand Prediction