Traditional proppants used in hydraulic fracturing have strongly water-wet surfaces, which retain water within the proppant pack and reduce the relative permeability to hydrocarbons. Oil-wet proppants have been evaluated, but pose significant operational challenges and have yielded poor recovery of treating fluids in the laboratory suggesting unsatisfactory hydrocarbon production if applied in the field. This paper describes the development and testing of a new proppant designed to exhibit a neutrally-wet surface. The modified surface does not have a preferential affinity for oil, gas or water, and therefore will not promote the preferential entrapment of any phase within the proppant pack. This concept yields significant advantages under multiphase flow conditions.
Laboratory results are presented showing dramatic improvement in the multiphase flow performance of the neutrally wet proppant. Pressure losses due to the simultaneous flow of water, gas and liquid hydrocarbons are significantly reduced leading to an improvement in relative permeability to hydrocarbon production. The surface treatment is resistant to abrasion, can withstand both acidic and basic environments, and can be used at reservoir temperatures up to 400° F. Testing and field application have also confirmed the compatibility with common fracturing fluid systems.
The neutral wettability proppant is expected improve the recovery of frac fluids, achieving longer effective fracture lengths through superior clean-up of the fracture. In addition to improved frac lengths, production rates are further increased by improved effective conductivity under realistic multiphase conditions. Field results will be presented which illustrate the positive results.
This proppant technology and the results described in this paper should be useful for completions, production and reservoir engineers dealing with hydraulically fractured wells, particularly in oil and condensate-rich reservoirs that are particularly challenged by multiphase flow. The implementation of this technology should improve completion effectiveness and well economics.