Development of delayed breaker system to remove polymer damage in hydraulic fracture reservoir

  • Mumin Abdalla Abdelrahim

    Student thesis: Master's Thesis

    Abstract

    Hydraulic fracturing commonly referred to as fracking is a widely used technology to enhance the productivity of low-perm reservoirs and the aqueous-based fracturing fluids use Guar as the rheology builder. Residual polymer layer over the fractured surface results in a reduced matrix to fracture permeability, causing reduced well productivity. The study begins with the development of high-temperature stable mannanase using 'protein engineering' tools, to minimize denaturation at high temperatures and the underlying formation chemistry, followed by optimization of polymer, crosslinker, and breaker concentration through the measurement of rheological properties at moderate to high temperature. Initial studies were conducted using HT-HP filter press and ceramic discs as porous media for visual inspection of polymer cake dissolution efficiency. Final conclusions were drawn from the simulated coreflooding studies, wherein the injection and production return permeabilities were investigated on post-fractured and enzyme-treated cores on two different modes. In the first set, the breaker was mixed with the frac fluid, where as in the second, the breaker treatment was applied once the frac fluid is in place. Thermal stability of the enzyme breaker vis-a-vis viscosity reduction and degradation pattern of linear and crosslinked gel observed from the break test showed that the enzyme is stable up to 250 oF and is able to reduce viscosity by more than 1800 cp (99% breaking ability). Visual observation from HP-HT filtration loss studies shows almost no polymer residue on the ceramic discs. The return permeability studies performed on sandstone cores shows that the effectiveness of the polymer chain-breaking ability is higher in the case of cross-linked gel compared to linear gel. It is also seen from comparative performance studies that the breaking ability enhances when the breaker is in second phase treatment instead of being mixed with the frac fluid. The simulated core flood runs conducted indicated a filter cake deposition due to frac fluid leak-off. leading to reduction of permeability from 95 mD to 0.3 mD simulating formation damage in most cases. The results illustrated a restoration of up to 95% of the production and injection permeability.
    Date of AwardMay 2021
    Original languageAmerican English

    Keywords

    • Core flooding; Fracturing fluid; Formation damage; enzyme; High pressure & temperature filtration.

    Cite this

    '