THE APPLICATION OF THE HIGH RESOLUTION HEWLETT-PACKARD QUARTZ CRYSTAL PRESSURE GAUGE TO FORMATION EVALUATION IN THE GIPPSLAND BASIN

Abstract

Over the period 1974-1977 Esso Australia Limited has conducted 35 pressure build-up tests, 24 well-to-well pulse tests, and 45 formation interval tests (using the Schlumberger FIT tool) in various parts of the Gippsland Basin. The primary pressure sensing device in all of these tests was the Hewlett- Packard quartz crystal pressure gauge. The pressure build-up tests were performed in both oil and gas wells whilst pulse testing has to date been limited to oil reservoirs. The formation interval tests carried out on offshore exploration and evaluation wells have tested both oil and water zones.

Although the overall experience has been that the gauge performs satisfactorily we have found that several precautions, relating both to the operation of the gauge and interpretation of the response, must be exercised in order to arrive at meaningful interpretations of reservoir parameters. Although the gauge is temperature compensated it requires a period of 20 minutes to reach temperature equilibrium during which time the gauge response varies significantly. Additionally, the high resolution of significant extraneous effects associated both with the wellbore and the reservoir, mask the pressure transient data and make interpretation difficult.

When adequate precautions are taken the gauge is highly effective in determining reservoir transmissibility (kh/p), reservoir storage (och), continuity between wells and reservoir zones, and for determining fluid gradients in exploration and evaluation wells which penetrate the high permeability sands characteristic of the Gippsland Basin.