Composite Well Cementing Additive for Drilling Fluid Contamination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The poor chemical compatibility between KCl/polysulfonate water-based drilling fluid and cement slurry leads to contact contamination during well cementing, causing issues such as abnormal gelation, casing blockage, and reduced well integrity, which complicates the cement placement process and affects the quality and stability of oil and gas wells.
Innovation Solution
A low-molecular-weight composite contamination-resistant additive composed of low-molecular-weight phosphonic acid polymer and silicate is introduced into the drilling fluid, which adsorbs on cement particles, shields active sites, and forms multi-dentate chelates with metal ions, inhibiting gelation and promoting hydration, thereby improving fluidity and stability of the slurry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If KCl/polysulfonate water-based drilling fluid is used for deep well drilling, then high-temperature stability and reservoir protection are improved, but chemical compatibility with cement slurry deteriorates, causing contact contamination
Solution Approach 1:
The patent introduces a contamination-resistant additive as an intermediary substance between the drilling fluid and cement slurry. This additive contains specific functional groups that can interact with both systems, preventing direct harmful interactions while maintaining the benefits of the KCl/polysulfonate drilling fluid system.
Solution Approach 2:
The patent modifies the chemical parameters of the drilling fluid by adding contamination-resistant additives that change the interaction characteristics between the drilling fluid and cement slurry. This alters the chemical compatibility parameter without compromising the high-temperature stability.
2Ease of operation
If spacer fluid and flush fluid are used in cementing, then cement placement is facilitated, but displacement efficiency cannot reach 100%, resulting in inevitable contact contamination
Solution Approach 1:
The patent extracts the contamination problem from the cementing process by introducing a contamination-resistant additive that specifically targets and prevents the harmful interactions between drilling fluid and cement slurry, allowing the spacer and flush fluids to function effectively without the contaminating effects.
Solution Approach 2:
The patent converts the potentially harmful contact between drilling fluid and cement slurry into a beneficial interaction by using the contamination-resistant additive to control the contact, transforming the contamination issue into an opportunity to improve cementing efficiency while preventing harmful effects.
3Productivity
If drilling fluid contamination is present, then cement slurry fluidity decreases and abnormal gelation occurs, but increasing spacer fluid amount and adding retarder can prolong thickening time
Solution Approach 1:
The patent applies preliminary action by adding the contamination-resistant additive to the drilling fluid before the cementing operation. This pre-treatment prevents contamination from occurring in the first place, eliminating the need for subsequent corrective measures like increasing spacer fluid or adding retarders.
Solution Approach 2:
The contamination-resistant additive acts as a mediator that prevents the harmful interaction between drilling fluid and cement slurry, thereby maintaining normal thickening time without requiring additional process steps or materials.
4Reliability
If polymer molecules in drilling fluid adsorb on cement particles, then gel structure forms and fluidity decreases, but using low-molecular-weight composite additive reduces this effect
Solution Approach 1:
The patent changes the molecular weight parameter of the polymer additive, using low-molecular-weight compounds instead of high-molecular-weight polymers. This parameter change reduces the adsorption capacity while maintaining the contamination-resistant function, thereby preserving fluidity.
Solution Approach 2:
The patent uses a composite additive system combining multiple components with different functions. This composite approach allows the low-molecular-weight components to provide contamination resistance while maintaining fluidity, overcoming the limitations of single-component systems.
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 additive significantly reduces spacer fluid usage, inhibits abnormal gelation, enhances sedimentation stability, and promotes hydration, ensuring well cementing quality and integrity under high-temperature and high-pressure conditions.
Implementation Method 1
The additive contains low-molecular-weight phosphonic acid polymer which adsorbs on cement particles, shields active sites
Implementation Method 2
forms multi-dentate chelates with metal ions, inhibiting gelation and promoting hydration
Data Source
AI summary
Disclosed is a low-molecular-weight composite contamination-resistant additive for well cementing, which includes: 60-85 parts by mass of low-molecular-weight phosphonic acid polymer solution and 15-40 parts by mass of silicate solution. The silicate solution is a low-modulus silicate solution with a mass fraction of 25%-45%, and the low-molecular-weight phosphonic acid polymer solution is a polymer solution with a mass fraction of 35%-60% and prepared from a phosphonic acid group-containing monomer, a rigid group-containing monomer and a carboxylic acid group-containing monomer. The present invention can form stable slurry after being added with drilling fluid, which meets the contamination-resistant requirements under low addition conditions and significantly reduces an amount of spacer fluid used. Compared with the retarder-type contamination-resistant additive that uses the retarding effect to prolong the thickening time, the present invention has a significant effect on abnormal gelation and reducing the consistency of mixed slurry.