Prevention of Water and Condensate Blocks in Wells

Abstract

Compositions and methods are given to prevent, alleviate and remedy water blocks and gas blocks (condensate block or condensate banking). Wettability modifiers are contacted with the formation to change the surfaces from water wet or oil wet to intermediate wet or gas wet. Preferred wettability modifiers include partially or completely fluorinated surfactants or polymers, for example fluorosilanes such as perfluorosilanes, urethane oligomers containing perfluoro alkyl moieties, fluoroacrylates, and fluoroalkyl containing terpolymers or their mixtures. Other examples include surfactants, for example viscoelastic surfactants such as cationic surfactants such as quaternary amines, and zwitterionic surfactants, such as betaines, optionally mixed with co-surfactants.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60 / 706238, filed on Aug. 5, 2005.FIELD OF THE INVENTION [0002] The invention relates to the prevention of water blocks and the prevention of condensate banking in oil and gas producing subterranean formations. More particularly, it relates to treating subterranean formations to change the wettability from oil or water wet to intermediate wet or gas wet. BACKGROUND OF THE INVENTION [0003] The accumulation of water near the wellbore in an oil or gas well can decrease the productivity by decreasing the relative permeability of oil or gas. The sources for water accumulation could be filtrate water from drilling mud, cross flow of water from water-bearing zones, water from completion or workover operations, water from matrix / fracture treatments, water from emulsions, etc. The problem of productivity decline because of an increase in near wellbore water saturation is known as water block. [0004] In gas w...

AI Technical Summary

Benefits of technology

[0009] The application of this method to treating a subterranean formation may involve single or multiple stages, separated into pretreatment, main and post treatment stages. The pretreatment stage may involve injection of a preflush of water or brine, one or more alcohols, one or more of other solvents, one or more clay stabilizers, one or more water-solvent mixtures, or one or more treatment fluids used in such oilfield treatments as matrix stimulation, and other treatments, one or more other fluids, or mixtures of such fluids. In the main stage, the wettability modifier may be dispersed or mixed in a carrier fluid that may be a solvent or water and may be injected into the well. Optionally, the formation may be soaked in the fluid that contains a wettability modifier for a period of time (shut-in period). The soaking may not be necessary for some wettability modifiers, some formations, or some conditions. The wettability modifier adheres to the formation by adsorption, chemical bonding, aggregation, electrostatic attraction, precipitation, aggregation, etc. In a typical post treatment stage the fluid injected in the main stage is displaced immediately aft

Problems solved by technology

The accumulation of water near the wellbore in an oil or gas well can decrease the productivity by decreasing the relative permeability of oil or gas.

In gas wells, in addition to water, liquid hydrocarbons that accumulate near the wellbore can also decrease the productivity of gas.

In addition to such external sources, the liquid hydrocarbons that condense out of the gas phase (called condensates) due to the decline in pressure below the dew

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