The paper describes a novel methodology to construct distributed formation damage across openhole wells in carbonate reservoirs and to evaluate the effects of damage on zonal productivity. This methodology improves the prediction of well productivity by identifying the contribution of various types of damage to zonal productivity. This is critical for efficient decision making concerning well-completion and field-development options, particularly at the early stages of greenfield development.
Numerous papers have investigated near-wellbore damage caused by drilling and acid, but the majority of these studies assume a homogeneous anisotropic reservoir and a perfectly horizontal well with constant diameter. In practice, these assumptions are unrealistic, especially when dealing with multilayered carbonate reservoirs. The proposed methodology in this paper relies on more-realistic assumptions made on the basis of actual well and reservoir data.
The case presented in this study involves a horizontal openhole well drilled across a multilayered oil-wet carbonate reservoir of a greenfield, with baffles and barriers present between reservoir layers. The study evaluates the damage types experienced by the formation and their effect on productivity.
A discussion of formation damage, including the mathematical bases of the skin concept, geometrical skin, drilling-induced skin, and the productivity index (PI) of a horizontal well, is included in the complete paper....
Formation Damage: A Novel Approach in Evaluating Zonal-Productivity Loss
01 February 2017