Uniform zonal coverage of the entire treatment interval is essential to the success of matrix stimulation treatments, especially for long intervals with high degrees of heterogeneity. In such cases, without effective diversion, the injected fluid will follow the path of least resistance, and very little treatment fluid will enter into low-permeability or highly damaged zones. However, effectively and economically diverting fluids from high-permeability zones to low-permeability zones has always been a challenge.

In this paper, a new non-damaging diversion or fluid-loss-control system is discussed that provides high differential pressure for the fluid flow by forming a low-permeability filter cake on the formation face or bridging the perforation tunnel, or by plugging pore throats, which helps divert fluid to other zones. The system consists of degradable polymer particulates and food-grade legume particulates whose particle size is relatively smaller than the polymer particulates. The laboratory test results show that the system provides good leakoff control and sustained a differential pressure as high as 2,300 psi. This system can be used in both non-acidic and acidic (up to 15% hydrochloric [HCl] acid) medium for temperatures up to 250°F. The effects of temperature and carrier fluid on the performance of this system are discussed.

The mixing procedure for preparing the blend, high-pressure/high-temperature (HP/HT) filter-press experiment setup, test procedure, results of experiments, and degradation behavior of the materials used in the system are described. The newly proposed system is suitable for various applications, such as (1) diversion during matrix treatments of long intervals, (2) fluid-loss or lost-circulation control, and (3) plugging of natural fractures.

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