Processing and analysis of transient pressure from permanent down-hole gauges
With the permanent down-hole gauge (PDG) widely installed in oilfields around the world in recent years, a continuous stream of transient pressure data in real time are available, which motivates a new round of research interests in further developing pressure transient analysis techniques. PDG data is recorded under the unconstrained circumstances, so that it cannot avoid effects due to noise, rate fluctuation and interference from other wells. These effects make the measured pressure trends declining or rising and then obscure or distort the traditional flow behavior, which makes the following analysis difficult. In this thesis, the problems encountered in analysis of PDG transient pressure are investigated. A new algorithm, multi-well deconvolution, and corresponding computer codes are developed. The algorithm is based on linear recursion with added non-linear least squares optimization to deal with the noise problem in time domain. With this developed algorithm, the inter-well interference effect can be extracted and the variable-rate superposition effect can be solved at the same time. New deconvolution-based rate transient analysis and pressure transient analysis methods are both proposed in this thesis. Numerical well testing synthetic studies are performed to demonstrate these procedures. The results prove that the new method works well in homogeneous reservoirs with two wells flowing at single phase, multiple rates.