Automated Pressure-Transient Analysis - Use Smart Technology
Authors: Denney Dennis 
Published: February 2015

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 144327, ’Automated Pressure-Transient Analysis - Using Smart Technology,’ by Hugh Rees, John Foot, and Richard Heddle, BP plc, prepared for the 2011 SPE Digital Energy Conference and Exhibition, The Woodlands, Texas, 19-21 April. The paper has not been peer reviewed.
Continuous live data feeds are used for automatic real-time estimates of reservoir pressure from buildup analysis and to evaluate well performance. The intent of pressure-transient analysis (PTA) was to provide permeability, skin, and reservoir-pressure estimates by use of traditional buildup/falloff techniques. Using this system, data are collected every time there is a shut-in event on every well for which the tool is enabled. Smart scheduling is adopted during a complete field shut-in so that all wells can be interpreted together. The automated technology was built in parallel with a tool for recording production flow tests by use of flowmeter or separator data. Combining the results with sampling and other data provides consistent auditable results that can be used by reservoir-modeling tools and other systems.
Introduction
Pressure management is a fundamental element of reservoir performance, and ongoing knowledge of reservoir pressure is key to the field-depletion strategy. With modern technology and monitoring, it is possible to acquire continuous data from field sensors. Assembling the data to yield useful information is difficult, but much valuable pressure data can be overlooked if it is processed manually. The challenge was to use conventional PTA, but do it automatically in real time using the live data feeds, and do it in the background with no user intervention. In this way, all pressure transients of sufficient quality would be analyzed and more valid reservoir-pressure information would be available than before.
The Foundation
Since 2002, much work has been performed to create a universally deployable, global software application that can process continuous data feeds from remote sites. By making the system universal and Web based, rather than a locally deployed application, consistency and global transportability were attained. The system is called the integrated-surveillance-information system (ISIS), and it provides the foundation upon which other technologies can be built, such as modular plug-in utilities.
ISIS monitors wells, the plant, and anything that has a sensor feeding into a control room. The system runs 24 hr/D, acquiring data from all types of sensors. Calculations also are made on the data continuously to enhance functionality.
Sensor data and calculations are stored in “historians,” enabling access later for trending, diagnostics, and further analysis. Presentation of data follows templated patterns, and an example of a basic surveillance screen is shown in Fig. 1. The example displays a pressure buildup and shows downhole and surface pressures and temperatures. The background is colored according to well state. Similar types of screens appear the same everywhere, for global consistency. Users do not have to refamiliarize if they are switching between, for example, Indonesia and the Gulf of Mexico.