Methods for fraccing oil and gas wells

Abstract

A method for stimulating or fraccing an oil or a natural gas well by adding a liquefied hydrocarbon such as liquid petroleum gas and liquefied natural gas, a proppant and a diluent such as carbon dioxide, nitrogen or mixtures thereof to the well. The order of addition is typically liquefied hydrocarbon then diluent but this order can be reversed and in other circumstances the liquefied hydrocarbon and diluent can be mixed together and fed to the well as a mixture.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority from provisional patent application Ser. No. 61 / 776,956 filed Mar. 12, 2013.BACKGROUND OF THE INVENTION[0002]In the production of natural gas from shale or other “tight-gas” formations, hydraulic fracturing (or “frac” or “fraccing”) is used to break up the rock around the well bore and reduce the resistance to gas flow. The frac technique generally requires injecting into the well large amounts of fluids that are compressible like nitrogen or carbon dioxide or incompressible such as water or liquefied petroleum gas. The fluids are pumped to high pressure to create large compressive forces around the well bore. These forces break the rock and create tiny fissures for gas flow.[0003]The stimulation of natural gas containing formations, such as shale gas has been the subject of intensive study. Several methods of fracturing these deposits are known and incompressible fluids such as water with other che...

AI Technical Summary

Benefits of technology

The patent describes a method of increasing the production of oil or natural gas from a well by stimulating it using a process called fracturing. This involves using substances called diluents to modify the properties of the oil or gas mixture, making it easier to separate from other gases. The diluents used in the process include carbon dioxide, which is effective because of its high density and heat capacity. The patent also mentions the use of liquefied hydrocarbons, which can be advantageously used in the process due to their higher density and temperature. Overall, the patent provides a technical solution for increasing the yield of oil or gas from oil and gas wells.

Problems solved by technology

The use of water results in the generation of a large amount of waste that is laden with chemicals and creates an expensive disposal issue.

However, the frac gas generated upon drilling has a high initial content of carbon dioxide and nitrogen.

This mixture can be difficult and expensive to separate and inevitably leads to natural gas losses and even venting of the initial diluted natural gas to the atmosphere because it cannot be readily flared.

However, injection of LPG at high pressures carries some risk involving explosions.

Although the concentration of energizing gas decreases quite rapidly in the beginning of the process, achieving the required levels may take considerable time (up to 30 to 45 days).

Such techniques may include N2 and / or CO2 separation by using membrane and / or adsorbent (PSA / VSA) technologies, which involves the deployment and operation of relevant equipment, which in turn adds cost to the natural gas production process.

While there are a variety of potential benefits to using LPG fracturing for shale energy development, there may be some potential disadvantages, such as increased costs for conducting the fracturing treatment, increased explosion hazards, and limited capacity to utilize this technology on a wide commercial basis.

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