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Preheating Tools for Steam Injection Wells

IP.com Disclosure Number: IPCOM000238627D
Publication Date: 2014-Sep-08
Document File: 2 page(s) / 125K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method of preheating tools for use in steam injection and geothermal wells is discussed. This process reduces the thermal shock and thermal gradients that might cause a tool to become inoperable. This is especially true in the case of degradable glass materials, cast materials, and high-temperature seals. The process enables the use of conventional tools such as ball-actuated sliding sleeves with dissolving balls in steam injection applications, e.g. steam-assisted gravity drainage (SAGD) wells.

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Preheating Tools for Steam Injection Wells

A method of preheating tools for use in steam injection and geothermal wells is discussed. This process reduces the thermal shock and thermal gradients that might cause a tool to become inoperable. This is especially true in the case of degradable glass materials, cast materials, and high-temperature seals. The process enables the use of conventional tools such as ball-actuated sliding sleeves with dissolving balls in steam injection applications, e.g. steam-assisted gravity drainage (SAGD) wells.

Steam injection wells have become much more common in the last 5 years. These wells allow for the production of much more viscous oil, such as that found in the tar sands of Canada, by warming up the bitumen to the point that it will flow more freely. In some cases, the steam injection helps to sweep the oil toward a separate producer well as shown in the Steam-Assisted Gravity Drainage (SAGD) schematic in Figure 1. With the increase in steam injection wells has come a corresponding need to adapt traditional well tools and equipment to this demanding environment. Many of the injection wells tend to be relatively shallow, so the hydrostatic pressure is low, but the temperatures can exceed 500° F. These high temperatures limit the use of off-the-shelf tooling, especially in cases where thermal shock or degradation can cause deleterious effects.

Figure 1: Steam injection well schematic in a SAGD application

An example of this temperature limitation is seen with some types of dissolving materials. Dissolving materials have found growing acceptance in more traditional applications. For instance, an operator can


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use a dissolving ball with a ball-shifting sliding sleeve system in order to actuate the sleeves without requiring a separate intervention to remove the balls. Most of these dissolving materials are metal alloys or advanced polymers, and both can experience a reduction in mechanical properties at high temperatures. One option for an alternative material is a dissolving glass, which has been shown to retain a significant portion of its strength at higher temperatures. The dissolving glass materials are non- flammable and have a melting temperature over 1200°F. A tool constructed from a dissolving glass could be made from borax or boric oxide, sodium borate, sodium tetraborate, or disodium tetraborate. A dissolving glass downhole tool has been shown to hold at least 10,000 psi pressure differential. However, during testing, it was found that some types of dissolving glass...