Abstract

Permanent Down-hole Gauge (PDG) has been widely installed in the oilfield around the world in recent years. One of the challenges in analyzing long-term, real-time, dynamic data such as transient pressure from PDG is the diagnostic and analysis of data with interference from other wells during the production. This type of data is very common in practice, while the published technique such as deconvolution algorithm failed in handling this problem.

Based on traditional interference test theory, muti-well deconvolution algorithm has been developed to address the problem in handling transient pressure with interference. A computer programme has been coded; a number of synthetic cases were studied, which proved that the developed algorithm works well for the problem stated above.

This paper presents the study results of applying the developed multi-well deconvolution technique in the diagnostic, processing and analysis of the numerically simulated transient pressure with interference. It was demonstrated that the interference effect can be identified, the published deconvolution algorithm failed in handling such data set, while the developed multi-well deconvolution algorithm worked well.

The paper shows that only after this data processing procedure, further analysis of the transient pressure data using methods such as decline curve analysis etc. is possible.

Introduction

Permanent Down hole Gauges (PDG) are pressure and temperature real time monitoring systems installed at the bottom hole of a well near the reservoir. The main objective of PDG is to help the reservoir management and the production by continuously measuring pressure and temperature in the reservoir.

Data from permanent down hole gauges are characterized by long term and large volume. They have the potential to provide more information about a reservoir than those from relatively short test duration. Especially, the long-term, real-time, dynamic PDG data involves lots of multi-well interference information, which could be analyzed to get inter-well reservoir properties, the degree of communication between wells, and reservoir heterogeneity.

Multiwell interference effect is popular in mature reservoirs. It becomes dominant in high-permeability reservoirs, as well as in some intermediate- permeability or low-permeability reservoirs with short inter-well distance. Such effect makes the measured pressure trends declining or rising during the test sequence. This abnormal phenomenon can obscure or distort radial flow behaviour, which makes the well test analysis difficult, i.e. the construction of the incorrect semi-log straight line or the incorrect radial flow regime on a pressure derivative log-log plot could be misleading.

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