Improving Gas Reservoir Understanding by Using Deconvolution

Abstract

Reservoir surveillance is one of the key tasks for any gas field development to understand its reservoir size, connectivity, porosity and permeability characteristics, and boundaries. Pressure transient test is the most widely used method, which provides all information above to support selecting the appropriate asset development strategies. Unfortunately, for fields with horizontal/high deviated wells and/or high H2S (sour gas) reservoirs, downhole pressure data can’t be easily acquired due to safety and cost-effective reasons. In addition, for gas fields with high deliverability and production demand, wells are required to open most of the time thus pressure build-up tests are often not available. What to do to maximize the value of the available pressure transient tests information and to minimize the operational cost and execution risk?

This paper is to present the current experience at the Joint Venture gas project, utilizing deconvolution to improve the quality of pressure transient tests and expand understanding on reservoir characteristics. There are several advantages in applying this method: (a) no extra cost or production loss from closing wells for test, and therefore, no operational risk from it; (b) it improves the reliability of interpretation from existing tests, whose quality could be contaminated by offset well interference or raw data quality issue; and (c) it provides valuable information about reservoir boundary when this information is covered by offset well interference.

In brief, effective use of deconvolution is considered as the best practice of improving the reliability of pressure transient tests, and thus, improving the understanding and the quality of gas field reservoir surveillance program. It has no extra operational cost and risk since it is purely mathematical method. Case study will be shared.