Well-Testing Operations in High-Temperature Environments - Worldwide Experiences and Best Practices
Authors: Denney Dennis 
Published: February 2015

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper OTC 21060, ’Challenging Well-Testing Operations in High-Temperature Environments - Worldwide Experiences and Best Prac tices Learned,’ by Alejandro Salguero, SPE, Edgar Almanza, and Josmar Haddad, SPE, Halliburton Energy Services, prepared for the 2010 Offshore Technology Conference, Houston, 3-6 May. The paper has not been peer reviewed.

Wells with bottomhole temperatures in excess of 300°F are classified as high-temperature (HT) wells. Many offshore developments with these conditions offer large hydrocarbon reservoirs. All, however, have presented significant challenges in terms of operational planning, equipment, engineering design, and job execution with respect to HT-well testing. Different reservoir scenarios required changes in procedures, equipment configuration, and safety requirements. All jobs had to consider environmental criteria in addition to the operator’s testing policies.  

Introduction

Traditionally, well testing is a reliable dynamic method to acquire a variety of information from the reservoir, including permeability, formation damage, bottomhole pressure and temperature, fluid samples, and production quantification. Over time, methods and equipment have evolved, expanding well-test capabilities to different scenarios and adapting to more-demanding environmental and safety constraints. In recent years, high-pressure/high-temperature (HP/HT) wells have become more common. Documented experience in similar cases will be well received because it provides relevant information that will help to make appropriate decisions. With HT wells defined as having bottomhole temperatures in excess of 300°F, extreme-HT wells are defined as wells having bottomhole temperatures between 350°F and 400°F.

Background

As shown in Fig. 1, many wells around the world with bottomhole temperatures above 300°F have been tested. Tool configuration has changed little because equipment reliability has improved. The lessons learned are extremely valuable for planning and design. Extreme temperatures represent the main challenge for the equipment, particularly for electronics, elastomers, explosives, and some surface equipment, including flexible hoses. In most of these cases, a deep-well simulator was used to test equipment above the expected conditions.

Design Consideration

Elastomers. The following service conditions must be considered before selecting the proper elastomers.

Fluids to be sealed: Consider the type of well fluid, including drilling mud, aggressive brines (such as formiates or calcium bromides), acids, and alcohols.

Temperature range: Including minimum and maximum operating conditions along with thermal cycling and potential exclusions. Some seals are not appropriate for low temperatures (i.e., seabed in offshore wells or cold-fluid injection).

Pressure range: Maximum and minimum operating range must be considered along with the compression and decompression rate if the pressure is high.

Unusual well procedures.