A New Model to Predict and Quantify Sand Production for Unconsolidated and Low Consolidated Reservoirs

Many of world oil reserves are stored in Heavy Oil reservoirs, which have low levels of consolidation and deform permanently under the influence of mechanical stresses. During Heavy Oil production, the mechanical stability of the reservoir is affected by different factors such as the fluid flow, current stresses regime, rock strength, completion type, water intrusion among others, which can cause sand production. This phenomenon occurs in many of the exploitation processes performed in an oil well and is a relevant factor in problems related with wellbore and surface equipment damage, wellbore stability, and reservoir productivity, among others. It has widely seen that these reservoirs behave mechanically in an elastoplastic way, in which rock strains can be of both types, elastic and plastic. Many investigations are focused on determining the onset of sand production, but few attempt are made to quantify the amount of produced sand according to the phenomenology of the problem. In order to predict and quantify the produced sand, a 3D single well numerical model is developed solving the single-phase fluid flow coupled with geomechanics for a reservoir with elastoplastic behavior, which uses the Mohr Coulomb failure criterion. This model emphasizes on the effects near wellbore and integrates a sand erosion criterion as a function of the rock plastic strain and the fluid flow velocity. The entire model takes into account changes in the porosity and permeability as a function of effective stresses, strains and produced sand mass. Initially, an experimental sand production test is studied for understanding of the phenomena involved in the sand production events, and then the results' test are modeled and matched using the numerical model presented in this article. First, the experimental test is modeled matching its mechanical behavior as a function of the measured data in the test and the rock properties. Then, the experimental sand production is modeled using the proposed sand production criterion. The obtained results exhibit a good match especially between the experimental and the modeled sand production. Also as results, petrophysical variables such as porosity and permeability are highly affected by strain and sand production, highlighting the relevance of this type of models. Although this model shows a high complexity, it allows a further analysis of the related variables and thus to visualize options to increase hydrocarbon production by harnessing the potential of this type of reservoirs.