Self-Pressurizing Alkali Silicate for Subterranean Zonal Isolation
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Solution Overview
Problem
Soluble alkali silicate-based systems for conformance control in petroleum reservoirs face issues such as syneresis (shrinking) and poor zonal isolation, leading to gas migration and excessive water production, due to their rigid nature and lack of a tight seal.
Innovation Solution
A self-pressurizing composition comprising a soluble alkali silicate, a gas generating additive (like metals that produce hydrogen gas), and a setting agent, which can be coated or uncoated, to control expansion and setting times, ensuring a tighter seal in subterranean spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If soluble alkali silicate-based systems are used for conformance control, then penetration and thermal stability are improved, but syneresis (shrinking) and rigid fracture occur leading to poor zonal isolation
Solution Approach 1:
The patent changes the physical-chemical parameters of the silicate system by adding gas-generating additives and controlling the setting reaction to produce expansion that counteracts syneresis shrinkage, transforming the volume change behavior from purely contracting to expanding then setting
Solution Approach 2:
The patent creates a composite system combining soluble alkali silicate with gas-generating additives (such as aluminum powder, zinc dust, or other reactive metals) and setting agents, forming a multi-component composition that achieves both penetration and reliable sealing
2Reliability
If soluble alkali silicate gels are formed, then conformance control is achieved, but the gel shrinks and creates poor zonal isolation
Solution Approach 1:
The patent applies preliminary anti-action by incorporating gas-generating additives that produce expansion pressure before the gel fully sets, counteracting the impending syneresis shrinkage and maintaining volume stability throughout the setting process
Solution Approach 2:
The patent utilizes phase transitions of gas generation from the reactive metal additives, where the solid metal reacts with the alkaline silicate solution to produce hydrogen gas bubbles, causing volume expansion that stabilizes the gel structure
3Stability of the object's composition
If gas generating additives are used in cement slurry, then expansion and settlement prevention are improved, but high reactivity and uncontrolled gas generation occur
Solution Approach 1:
The patent uses setting agents as intermediaries that control the timing and rate of gas generation by regulating the reactivity between the metal additives and the silicate solution, preventing premature or uncontrolled gas evolution
Solution Approach 2:
The patent prepares the silicate composition with gas-generating additives in advance, allowing controlled reaction initiation upon contact with formation water or through controlled setting conditions, ensuring expansion occurs at the desired time and location
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 self-pressurizing system effectively expands to create a tighter seal, reducing gas migration and water production, while allowing for controlled expansion times and enhanced strength, thereby improving zonal isolation and petroleum recovery.
Implementation Method 1
When a suitable metal is added to the cement slurry, the high pH environment results in the production of hydrogen gas
Implementation Method 2
soluble silicates set via a gelation/polymerization reaction caused by a loss of alkalinity
Implementation Method 3
Soluble silicates can also be set via a precipitation reaction with metal cations
Implementation Method 4
Soluble silicates may also be made to set via a dehydration reaction where the loss of water causes the soluble silicate to thicken and eventually revert back to a glass
Data Source
AI summary
Compositions and methods are disclosed for sealing subterranean spaces such as natural or induced fractures, vugs or annular spaces. The composition is composed of a base fluid consisting of a soluble alkali silicate, a gas generating additive, water, solids, and a setting agent. The gas generating additive may be coated or uncoated. The gas generating additive may also be in the form of a slurry. In the case of coated additives, the coating may act as a retarder or an accelerator to the expansion and setting agent of the soluble alkali silica. Similarly, the choice of carrier fluid in a slurry may retard or accelerate the expansion and setting of the alkali silicate-based plug.