Pressure rate deconvolution – Corrib gas field case study
By Alex Thatcher, Petroleum Engineer, OPC
I was delighted to be asked to share an example of the work I have been doing recently for Nephin Energy which was to integrate our PTA work using PIE and ConvEx into our Full field numerical simulation model using tNavigator. I took part in a webinar hosted by Rock Flow Dynamics (recording is shown below). There has been immediate interest from a number of international oil companies asking if we could perform similar analysis on their assets. Please get in touch if you want to find out more.
Pressure-rate deconvolution and its use in the reservoir simulation of the Corrib Gas field | presented by Alex Thatcher, OPC
Abstract of webinar
This project presents the latest development in pressure-rate deconvolution and its applicability in reservoir characterisation and reservoir simulation of the Corrib Gas field, Offshore Ireland. Pressure rate deconvolution is a method for converting pressure and rate data obtained from a well with a variable rate history into a much simpler form of constant-rate drawdown-pressure response function.
The drawdown response created by pressure rate deconvolution spans the entire length of the production history of the well (in our case several years) and is presented along with its’ Bourdet derivative. The pressure and derivative curves can then be analysed using the basic PTA equations originally developed for a well producing at constant rate. The analysis of the results from Pressure-rate deconvolution allow evaluation of formation permeability, reservoir heterogeneities, shape of reservoir compartment drained by the well, quality of the completion (Skin) and analysis of the pressure behaviour during boundary dominated flow which provides an estimate of connected pore volume drained by the well.
The advantage of Pressure Rate Deconvolution over other PTA methods is it adds thousands of hours to the Bourdet derivative which greatly improves identification of the flow regimes required for evaluation of some / all the above mentioned Well/Reservoir Parameters. In essence, pressure rate deconvolution produces an improved fingerprint of the well which can show the engineer everything they need to know about the reservoir and completion in one plot.
The Bourdet derivative can be used for many matching applications and this project focuses on integrating the results of Pressure Rate Deconvolution into the history matching process of the full field reservoir simulator (2.5 million cells including upscaling). By applying pressure rate deconvolution on the simulation model, the engineer can test the applicability of the model to see if it truly reflects the completion and reservoir properties as captured by Pressure Rate Deconvolution method and other Pressure Transient Analysis methods.
This project will demonstrate some of the features of tNavigator used to aid in this matching process
Pressure Transient Analysis
OPC specialises in Pressure Transient Analysis (PTA), also known as Well test analysis, which involves the interpretation and analysis of Drill Stem Test (DST), Extended Well Test (EWT) and Production/Injection permanent downhole gauge data.
OPC is one of the leading independent reservoir engineering consultants in the world providing services on a global basis to IOCs, NOCs and independent oil & gas businesses.
Reservoir engineering studies have included phase behaviour and equation of state modelling and production engineering.