Acid-Soluble Nano Carbonate Plugging for Tight Reservoir Pore Throats
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Solution Overview
Problem
Conventional calcium carbonate-based plugging agents exhibit poor plugging efficiency, high acid dissolution rates, and cause formation damage due to unstable operation and low adsorption capacity, particularly in multi-dimensional pore throats of tight reservoirs.
Innovation Solution
Development of an acid-soluble nanomaterial with specific hydrodynamic particle diameters (D10: 2-10 µm, D50: 8-31 µm, D90: 20-90 µm) formed by modifying nano-calcium or nano-magnesium carbonate with a hydroxylation and amination process, enhancing plugging capability and adsorption properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional calcium carbonate particles are used as plugging agents, then the plugging operation can be performed, but the plugging effect is poor and the acid dissolution rate is excessively high
Solution Approach 1:
The patent changes the particle size parameter from conventional calcium carbonate particles to acid-soluble nanomaterials with specific hydrodynamic diameters (D10: 2-10 μm, D50: 8-31 μm, D90: 20-90 μm). This parameter change enables the material to effectively plug pore throats while controlling the acid dissolution rate to meet operational requirements, resolving the contradiction between plugging effectiveness and dissolution control.
Solution Approach 2:
The patent uses composite acid-soluble nanomaterials comprising carbonate particles (calcium carbonate and/or magnesium carbonate) combined with organic modifiers containing amino groups, carbon chains, and hydroxyl groups. This composite structure enhances plugging capability while regulating acid solubility, simultaneously improving plugging effect and controlling dissolution rate.
2Reliability
If calcium carbonate particles are modified to improve plugging effect, then the plugging capability increases, but the adsorption capacity remains small and plugging rate for multi-dimensional pore throats is low
Solution Approach 1:
The patent introduces multiple new parameters including hydrodynamic particle diameter distribution (D10, D50, D90), amino group content (0.05-0.6 wt%), carbon chain length (20 or more), and hydroxyl group content. These parameter optimizations enable the nanomaterial to achieve high plugging rates for multi-dimensional pore throats while maintaining strong adsorption capacity.
Solution Approach 2:
The patent applies local quality modification by introducing functional groups (amino, hydroxyl, carbon chain) at specific locations on the nanomaterial surface. This localized functionalization enhances adsorption capacity and plugging capability in different regions of the pore throat structure, improving overall plugging effectiveness.
3Productivity
If conventional plugging agents are used, then the fracturing operation can proceed, but the retention volume of fracturing fluid is high causing formation damage
Solution Approach 1:
The patent employs acid-soluble nanomaterials that serve as temporary plugging agents during fracturing operation, then dissolve completely through acidification after the operation. This discarding mechanism reduces retention volume of fracturing fluid and eliminates formation damage, while recovering the plugging function when needed.
Solution Approach 2:
The patent converts the potential harm of high retention volume and formation damage into benefit by using acid-soluble nanomaterials that can be deliberately dissolved. The acid dissolution, which could be harmful if uncontrolled, is instead used as a beneficial mechanism to reduce retention volume and protect formation after plugging is complete.
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 nanomaterial effectively plugs multi-dimensional pore throats, reduces retention volume, and minimizes formation damage by dissolving post-operation, facilitating fluid flowback and lowering filtration loss in fracturing fluids.
Implementation Method 1
it can be dissolved in an acid after playing a plugging role to promote flowback of the working fluid
Implementation Method 2
has the capacity of adsorption and occupation after entering into the pore throats to decrease retention volume of the fracturing fluid
Data Source
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AI summary
An acid-soluble nano material and a preparation method therefor and a use thereof, and a fracturing fluid, relating to petrochemical technology. The hydrodynamic particle size D10 of molecular aggregates of the acid-soluble nano material in water is 2-10 µm, D50 is 8-31µm, and D90 is 20-90µm. The preparation method for the acid-soluble nano material comprises: carrying out hydroxylation treatment on an unsaturated fatty monoacid, and carrying out a contact reaction between the hydroxylated unsaturated fatty monoacid and a nano carbonate raw material; and carrying out amination treatment on a product of the contact reaction, wherein the nano carbonate raw material contains a nano calcium carbonate raw material and/or a nano magnesium carbonate raw material. The acid-soluble nano material has the dissolution performance meeting fracturing construction requirements, can realize multi-size plugging in a compact reservoir and improve the plugging rate of a pore throat, and can enter the pore throat for adsorption and space occupation to reduce the retention amount of the fracturing fluid, thereby reducing damage to the reservoir.