Patent ID: 7013723

Claim:
An apparatus for the investigation of an earth formation traversed by a borehole, comprising: a) a first probe including means for injecting fluid into the formation or withdrawing fluid from the formation; b) a second probe vertically displaced relative to the first probe and in fluid contact with the formation, said second probe including a first fluid flow line and a first pressure measurement means for measuring pressure in said first fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe; and c) a third probe azimuthally displaced relative to the first probe and in fluid contact with the formation, said third probe including a second fluid flow line and a second pressure measurement means for measuring pressure in said second fluid flow line which results from the fluid being injected into the formation or obtained from the formation by the first probe, wherein said first fluid flow line has a first storage volume, said second fluid flow line has a second storage volume, and at least one of said second probe and said third probe includes means for adjusting at least one of said first volume and said second volume, said means for adjusting being controlled to reduce storage effects on interpretation of data obtained from said second probe and said third probe.