Withanolide corrosion inhibitor for carbon steel

Abstract

Acidic fluids used in wells or pipelines cause corrosion of carbon steel. Methods for inhibiting corrosion include contacting carbon steel with a fluid having an aqueous acidic phase including a material selected from the group consisting of: a material of a plant in the Solanaceae family, an extract of a material of a plant in the Solanaceae family, a withanolide, a source of a withanolide, a withanolide derivative, a source of a withanolide derivative, and any combination thereof. The methods have wide application in various kinds of operations involved in the production or transportation of oil and gas, such as acid stimulation in a well or remedial treatment in a pipeline.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Not applicable.TECHNICAL FIELD[0002]The inventions are in the field of producing crude oil or natural gas from subterranean formations. More particularly, the inventions relate to corrosion inhibition of carbon steel in wells or transportation pipelines.BACKGROUNDAcidic Fluids, Corrosion, and Inhibition[0003]Acidic fluids are present in a multitude of operations in the oil and gas industry. For example, acidic fluids are often used in wells penetrating subterranean formations. Such acidic fluids may be used, for example, in stimulation operations or clean-up operations in oil and gas wells. Acidic stimulation operations may use these treatment fluids in hydraulic fracturing and matrix acidizing treatments. In operations using acidic well fluids, metal surfaces of piping, tubing, pumps, blending equipment, downhole tools, etc. may be exposed to the acidic fluid.[0004]Acidic fluids are sometimes used in pipelines that are used for the trans...

AI Technical Summary

Benefits of technology

The patent text describes a method to prevent corrosion of carbon steel that comes in contact with fluids containing acidic phases. The method involves adding a certain material from the Solanaceae family, or an extract of this material, along with withanolide or its derivatives to the fluid. This addition prevents the corrosion of carbon steel when it comes in contact with the fluid.

Problems solved by technology

Paraffin wax deposition obstructs the flow of oil, lowering oil production and interfering with transportation.

In addition, many fluids used in the oil and gas industry include a water source that may incidentally contain certain amounts of acid, which may cause the fluid to be at least slightly acidic.

Even weakly acidic fluids can be problematic in that they can cause corrosion of metals.

Corrosion can occur anywhere in a well production system or pipeline system, including anywhere downhole in a well or in surface lines and equipment.

The expense of repairing or replacing corrosion damaged equipment is extremely high.

The corrosion problem is exacerbated by the elevated temperatures encountered in deeper formations.

The increased corrosion rate of the ferrous and other metals comprising the tubular goods and other equipment results in quantities of the acidic solution being neutralized before it ever enters the subterranean formation, which can compound the deeper penetration problem discussed above.

In addition, the partial neutralization of the acid from undesired corrosion reactions can result in the production of quantities of metal ions that are highly undesirable in the subterranean formation.

A difficulty encountered with the use of some conventional corrosion inhibitors is the limited temperature range over which they may function effectively.

For example, certain conventional antimony-based inhibitor formulations have been limited to temperatures above 270° F. and do not appear to function effectively below this temperature.

Another drawback of some conventional corrosion inhibitors is that certain components of these corrosion inhibitors may not be compatible with the environmental standards in some regions of the world.

However, these compounds generally are not acceptable under stricter environmental regulations, such as those applicable or that will become applicable in the North Sea region.

Consequently, operators in some regions may be forced to suffer increased corrosion problems, resort to using corrosion inhibitor formulations that may be less effective, or forgo the use of certain acidic treatment fluids.

Yet another drawback of some convention corrosion inhibitors is the high cost.

In acid fracturing, an acidizing fluid is pumped into a carbonate formation at a sufficient pressure to cause fracturing of the formation and creating differential (non-uniform) etching fracture conductivity.

Further, as the crude oil is moved through cross-country pipelines, it can lose heat energy to the ground or environment and cool to a temperature well below 120° F.

This can be particularly problematic in subsea pipelines because the surrounding water on the seafloor is very cold, typically about 39° F.

To help prevent paraffin deposits, some cross-country pipelines are heated, which is very costly.

However, this is not feasible for subsea pipelines, which are in direct contact with the surrounding cold seawater.

Unless at least some of the buildup is removed from time to time, eventually the deposits can increase to the point where the conduit becomes choked.

Also, sometimes some of the paraffin deposits will release from the inside wall of a pipeline and cause a blockage.

Such a blockage can occur anywhere in the pipeline.

This paraffin deposition leads to reduced crude oil flow and under extreme conditions leads to complete blockage of the pipelines.

One of the thermal-chemical approaches is to use an acid-base reaction to generate heat, but this can also expose the metal of the pipeline to acid corrosion.