Effect of Back Pressure on Gel Pack Permeability during Conformance Control Treatment

Abstract

Description of the Paper:

Excess water production has become a significant problem for oil field operations as reservoirs mature. A newer trend in gel treatments is using preformed particle gels (PPGs) to reduce fluid channels through super-high permeability streaks/fractures. Therefore, water production decrease and sweep efficiency increase in mature oilfields. The achievement of the best PPGs treatment mainly depends on whether or not PPGs can successfully reduce the permeability of the channels to the level that we expect. This work sought to determine what factors influence the blocking efficiency of PPG on fluid channels. It will determine what factors effecting on PPGs pack permeability.

Results, Observations, Conclusions:

A transparent model was designed to observe the compression of gel particles in fluid channels at different back pressures, and thus to study the effect of different parameters on PPG blocking efficiency. Results presence that:

1. PPG pack in the fluid channels affected by the back pressure. It was determined that the increase of the back pressure decreased the PPG pack permeability.
2. Gel pack is compressed and its permeability is reduced as back pressure increases.
3. A permeable gel pack was formed in fluid channels by gel particles. The permeability of the gel pack depended on particle strength, particle size, brine concentration, and back pressure.

Applications:

The results can be used to optimize a PPG design. A gel pack with a desired permeability can be designed by selecting proper gel strength and particle sizes at reservoir pressures. This selection is very important for successful gel treatment because an optimized gel treatment design target on reducing the permeability to the degree as we planned.

Technical contributions:

In field applications, operators often increased either gel particle size or gel strength if they want to increase blocking efficiency. Contrary to the conventional concepts in PPG treatment practices, we find that gel particles can better block fluid channels if either weak and/or small particles are used for conformance control treatments.

AAPG Datapages/Search and Discovery Article #90214 © 2015 Southwest Section AAPG Annual Convention, Wichita Falls, Texas, April 11-14, 2015