Acid-Soluble Cement Composition for Wellbore Fluid Communication
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Solution Overview
Problem
Current cement compositions used to prevent lost circulation in subterranean formations are not easily dissolvable after setting, which hinders the restoration of fluid communication in highly permeable areas.
Innovation Solution
Development of an acid-soluble cement composition that includes a higher concentration of water and specific additives, allowing it to maintain pumpability during introduction and set within the formation, and subsequently dissolve upon contact with acid to restore fluid communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cement composition is used to prevent lost circulation, then fluid loss prevention is improved, but dissolvability after setting deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the cement by incorporating water-soluble salts (such as calcium chloride, calcium bromide, or sodium chloride) in specific concentrations (1-40% by weight of water). This parameter change enables the cement to maintain both its fluid loss prevention capability and its dissolvability in fresh water, resolving the contradiction between reliability and ease of manufacture.
Solution Approach 2:
The invention creates a composite cement system combining traditional cement components with water-soluble salts and optional organic polymers. This composite material structure allows the cement to exhibit dual characteristics: sufficient strength and fluid loss prevention when set, and complete dissolvability when exposed to fresh water, thereby resolving the contradiction between reliability and dissolvability.
2Duration of action of stationary object
If cement composition sets within formation, then lost circulation prevention is maintained, but fluid communication restoration becomes difficult
Solution Approach 1:
The patent introduces a dynamic property to the cement system through water-soluble salts that allow the cement to transition from a stable, non-dissolvable state to a dissolvable state. The cement dynamically responds to environmental changes (fresh water exposure) by dissolving, enabling fluid communication restoration while maintaining lost circulation prevention during the production phase.
Solution Approach 2:
The water-soluble salts act as intermediaries that facilitate the dissolution process. These salts create pathways for fresh water to penetrate and dissolve the cement matrix, enabling the transition from a sealed state to an open state without requiring mechanical intervention or causing formation damage.
3Loss of time
If extensive waiting time is required for cement to dissolve, then operational efficiency deteriorates
Solution Approach 1:
The patent optimizes the concentration and type of water-soluble salts to control the dissolution rate. By adjusting parameters such as salt concentration (1-40% by weight of water) and selecting specific salts with different solubility characteristics, the cement dissolves within a controlled timeframe, reducing waiting time and improving operational efficiency while maintaining effective lost circulation prevention.
4Ease of manufacture
If cement composition is made more dissolvable, then fluid communication restoration is improved, but pumpability during introduction deteriorates
Solution Approach 1:
The patent carefully controls the concentration parameters of water-soluble salts (1-40% by weight of water) and the water-to-cement ratio (200-800% by weight) to achieve an optimal balance. At these controlled parameters, the cement maintains sufficient viscosity and stability for pumpability during introduction, while still being sufficiently dissolvable when exposed to fresh water in the formation.
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 acid-soluble cement composition effectively prevents lost circulation, sets within the formation, and can be dissolved to restore fluid communication, ensuring efficient operation and reducing the need for extensive waiting times or equipment damage.
Implementation Method 1
an acid-soluble cement composition that includes a higher concentration of water and specific additives, allowing it to maintain pumpability during introduction and set within the formation, and subsequently dissolve upon contact with acid
Data Source
AI summary
A cement composition for use in a well that penetrates a subterranean formation comprising: cement; and water, wherein the water is in a concentration in the range of about 220% to about 800% by weight of the cement, wherein the cement composition is acid soluble. A method of treating a subterranean formation comprising: introducing the cement composition into the subterranean formation; allowing the composition to set; and contacting the set cement composition with an acid.