Influence of perforating charge interference on jet moulding and perforation penetration
Perforation is a key part of oil and gas production process,and perforation spacing is a main parameter that affects jet shaping and perforation penetration.Interference occurs between two adjacent perforating charges,and thus affects the jet quality and penetration.In this paper,the LS-DYNA software is combined with Arbitrary Lagrange-Euler(ALE)algorithm for operator separation,thus achieving the penetration of mass,internal energy and momentum of unit boundary.Taking the downhole perforation in an oilfield as an example,a three-dimensional model of perforating charge-gun-casing-cement sheath is built to analyze how perforating charge interference affects the jet moulding and perforation penetration.The results show that the perforating charge interference reduces the efficiency at which the total energy of perforating charges is converted to the jet energy.When the perforating charge spacing is 5.0 mm,the jet energy conversion rate of adjacent perforating charges reduces by 0.31%,the axial jet velocity decreases by 39 m/s,and the radial jet velocity increases by 20 m/s.When the perforating charge spacing is 3.5 mm,the jet energy conversion rate of adjacent perforating charges reduces by 2.21%,the axial jet velocity decreases by 130 m/s,and the radial jet velocity increases by 111 m/s.Moreover,the perforating charge interference leads to the decrease of axial jet velocity valid for penetration and the increase of radial jet velocity invalid for penetration.The increase of radial jet velocity impedes the jet quality to allow a possibility of jet divergence,thus reducing the perforation penetration.The numerical simulation reveals that the decrease of phase angle is accompanied with a decreased distance between jet lines,an intensified perforating charge interference,a reduced jet energy conversion rate,and a decreased perforation penetration.It is concluded that the research insights provide the quantitative influence of perforating charge interference on jet moulding and perforation penetration,which is theoretically referential for rationally optimizing perforation density and improving perforation penetration.
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