SPE Members
Abstract The application of fracturing to high permeability formations is presented.
The economic rationale for fracturing high permeability formations is different from conventional fracturing. The principal reasons for fracturing these formations are reviewed. Design and execution methods for these fracture treatments are presented where they differ from conventional fracturing.
High permeability formations often have a tendency to produce sand. The effect of fracturing on the sanding tendency and the potential of using fractures as a sand control method are discussed.
INTRODUCTION - WHY FRACTURE HIGH-PERMEABILITY FORMATIONS? Wells with high-permeability formations generally have a high enough productivity to economically justify development whereas lower permeabilities often require stimulation to be economically viable. However, the economics of fracturing high-permeability formations can be attractive in increasing the well productivity to reduce the number of wells required to develop a field or shorten the field life.
Net Present Value (NPV) analysis is often performed to compare stimulation alternatives and select the optimum treatment (figure 1). In high-permeability formations this analysis can be extended to compare the NPV of fracturing to the NPV of alternative projects such as infill drilling or gravel packing.
Damage Bypass Short, conductive, hydraulic fractures can be effective and economic in bypassing damage to reduce skin effect to zero in high-permeability formations. Such formations often have near-wellbore damage resulting from drilling, completion, or production practice. Removal or reduction of the skin is often achieved through injection of reactive fluids (often acid) to remove the damaging materials (in sandstone) or bypass the damage by dissolving the formation rock (in carbonates).
A highly conductive hydraulic fracture treatment offers a viable alternative for conditions which include wells where adequate diversion cannot be achieved damage penetrating far from the wellbore requiring excessive acid volumes formations sensitive to acid or other reactive fluids formations in which the type of damage is not known causing uncertainty in matrix treatment design.
Other damage mechanisms caused by near-wellbore, high flow velocities or large pressure gradients such as scale deposition fines movementnon-darcy flow within the matrix may be mitigated by providing a larger flow area through fracturing.
The primary objective is to remove the skin effect caused by damage and minimize subsequent damaging effects during production.
P. 555^