Forming Multiple Deviated Wellbores

Abstract

A system includes a primary wellbore and a plurality of secondary wellbores. The primary wellbore includes a substantially vertical portion extending from a terranean surface to a predetermined location above a first target subterranean formation; a curved portion coupled to the substantially vertical portion and extending through the first target subterranean formation above a second target subterranean formation containing at least one of oil or gas; and a substantially horizontal portion coupled to the curved portion and extending through the first target subterranean formation and adjacent the second target subterranean formation. The plurality of secondary wellbores are coupled to the primary wellbore and extend angularly downward into the second target subterranean formation.

Description

TECHNICAL BACKGROUND[0001]This disclosure relates to systems and methods for forming wellbores within a subterranean formation and, more particularly, to systems and methods for forming wellbores within one or more subterranean formations utilizing one or more deviated wellbore portions extending from an adjacent geological formation to a hydrocarbon bearing formation.BACKGROUND[0002]Over the last century, oil and gas has been produced from hydrocarbon-bearing geologic strata (“productive formation”) within the Earth's crust by drilling vertical wellbores, which penetrate these potentially productive layers. In most cases, the productive formations are horizontally-planed layers of solid sedimentary rock generally found at depths from approximately 2,000 feet to 20,000 feet below the surface. These productive formations usually range from 10 to 200 feet in thickness. Thus, it may be typical for a vertically-drilled oil or gas well to have less than one percent of its total wellbore ...

AI Technical Summary

Benefits of technology

[0019]Various embodiments of a multiple deviated wellbore system according to the present disclosure may include one or more of the following features. For example, the deviated wellbore system may include one or more horizontally-drilled wellbores drilled through one or more formations located above a targeted productive formation and a number of sharp-dipping wellbores into or through a productive formation. As used herein, “formation” may include one or more portions, or the entirety, of a body, or strata, of rock. The result may allow for easier, more efficient, and economical penetration into the target productive formation, greater efficiency in drilling the target productive formation and easier communication of fractures through and, in some cases, rubbilization of the formation. The deviated wellbore system may also allow for horizontal, or directional, drilling in competent formations (e.g., shale) above a highly organic targeted productive formation. The deviated wellbore system may also include drilling multiple wellbores, or paths, for fracturing, draining, and / or producing into and / or from the productive formation from a long radius horizontal-style wellbore to the productive formation. Thus, the deviated wellbore system may allow an entire drilling process to be conducted using an efficient and environmentally friendly compressed air or foam drilling process for both the horizontal wellbore section and the multiple drainage paths. The deviated wellbore system may result in an economic and environmentally efficient drilling process for horizontal wells that are developed to produce hydrocarbons (e.g., oil and / or gas).

[0020]Various embodiments of a multiple deviated wellbore system according to the present disclosure may include one or more of the following features. For example, the deviated wellbore system may allow for savings of millions of gallons of water during a traditional hydraulic fracing process by enabling the use of inert gases or high quality foam, thus eliminating the potential to contaminate the ground water and other sub-surface strata with the foreign hydraulic frac materials. Further, when water is used for a frac process, the deviated wellbore system may allow for the well system to be stimulated using very little water. For instance, the multiple drainage paths may be formed at specific intervals and spacings in order to minimize water requirements. In some cases, the deviated wellbore system may require as little as one percent of the water typically used to frac horizontal shale wells. Additionally, the deviated wellbore system may more quickly and efficiently produce hydrocarbons from a geological formation by, for example, encouraging more efficient rubbilization of the formation between two or more of the drainage paths.

Problems solved by technology

However, a number of productive formations that may be drilled vertically using the air circulation process may not be easily and / or efficiently drilled horizontally using the air circulation process.

The geologic characteristics of these formations and the altered flow dynamics of circulation mediums involved in drilling horizontal wellbores may make horizontal drilling through these formations difficult and expensive.

Horizontal wellbores through these formations may thus be difficult to drill even using the less efficient fluid “drilling mud” method.

Various natural gas producing regions of the United States, for example, may contain productive formations with great productive potential but which are composed of a highly organic shale rock that may be unsuitable for horizontal drilling using compressed air circulation drilling processes.

In some cases, however, a rock layer directly above or adjacent to the productive formation may be a lesser organic, more brittle, competent rock formation (e.g., shale) that may be well-suited for horizontal drilling using compressed air (or foam) drilling processes.

Thus, the use of water in fracing horizontal wells has been perceived as a threat to the fresh water balance of nature in certain river basins.

The cost to the well owner to assemble this amount of fresh water at the well site can be very high; in some cases exceeding several hundred thousand dollars.

The existence of the now-contaminated water at the surface presents additional economic and regulatory issues.

Using current processes and technology, disposal of this frac water can cost substantial sums per well, to say nothing of regulatory concerns generated by the storage, handling, and disposal of the frac water.

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