Alkyl Ester Spotting Fluid for Differential Sticking
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Solution Overview
Problem
Existing spotting fluids for freeing differentially stuck pipe in wells are time-consuming, may use corrosive and non-biodegradable substances, and require removal from the mud system after use, posing challenges in efficiency and environmental impact.
Innovation Solution
A spotting fluid composition comprising an invert emulsion with an alkyl ester derived from vegetable oils, such as oleic sunflower, canola, or jojoba oil esters, combined with water and an emulsifier, which is introduced downhole to interact with the stuck pipe, reducing the sticking bond modulus and ultimate sticking bond strength without the need for removal from the mud system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing spotting fluids are used to free differentially stuck pipe, then the pipe can be freed, but the process is time-consuming and requires hours of soak time
Solution Approach 1:
The patent changes the chemical parameters of the spotting fluid by using alkyl esters with specific molecular structures and properties. The fluid composition is optimized with specific ratios of alkyl ester to drilling fluid (1:1 to 4:1), and the alkyl ester itself has controlled properties (viscosity 10-1000 cSt, molecular weight 200-500 g/mol) to enhance its ability to penetrate and degrade the filter cake quickly, reducing soak time from hours to minutes while maintaining effective pipe recovery
2Productivity
If corrosive fluids are used to reduce or remove the filter cake seal, then the seal is effectively removed, but the fluids are not readily biodegradable and require removal from the mud system
Solution Approach 1:
The patent employs alkyl esters that function as temporary, single-use agents for breaking the filter cake seal. These esters are designed to be easily biodegradable and environmentally benign, allowing them to be introduced, perform their function of reducing the seal, and then naturally degrade without requiring removal from the mud system. This eliminates the harmful factors associated with corrosive, non-biodegradable fluids while maintaining effective seal removal
Solution Approach 2:
The patent converts the potential harm of using strong chemical agents into a benefit by selecting alkyl esters that are both effective at breaking the filter cake seal and environmentally friendly. The esters' chemical properties allow them to interact with and degrade the filter cake effectively, while their biodegradability ensures they do not create harmful residues, thus turning a potentially harmful process into a beneficial one
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The alkyl ester spotting fluid composition effectively reduces the sticking bond modulus and ultimate sticking bond strength of the mudcake, allowing for quicker pipe recovery with reduced environmental impact and no need for post-recovery fluid removal, demonstrating improved efficiency and sustainability.
Implementation Method 1
dehydrating agents such as anhydrous glycols, and acids, either alone or in combination, may be used in an attempt to free the differentially stuck pipe. For example, dehydrating agents may be used to dehydrate the filter cake to assist in relive pressure and break the vacuum seal
Implementation Method 2
WO 02/055627 A2 describes a composition for a spotting fluid and a method of using such spotting fluid for freeing differential stuck pipe in a subterranean well drilling operation. The composition comprises an invert water-in-oil emulsion comprising iso-butyl oleate as its external phase and either glycerin or calcium chloride and water as the internal phase.
Data Source
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AI summary
Alkyl ester spotting fluid compositions and processes for freeing differentially stuck pipe are provided. An alkyl ester spotting fluid composition includes an invert emulsion having an alkyl ester as the external phase and water as the internal phase. In some embodiments, the alkyl ester spotting fluid composition may include the alkyl ester invert emulsion and an emulsifier. The alkyl ester spotting fluid composition may be introduced downhole in the vicinity of a portion of a differentially stuck pipe such that the spotting fluid composition contacts the mudcake and frees the differentially stuck pipe.