def perforationskineffect(s_h=0, s_v=0, s_wb=0):
    """
    Calculate perforation skin effect or s_p given...
    s_h     == horizontal skin effect
    s_v     == vertical pseudoskin
    s_wb    == well bore blockage effect
    """
    s_p = s_h + s_v + s_wb
    return(s_p)