Elastic Granule Drilling Fluid for Heterogeneous Reservoir Protection
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Solution Overview
Problem
Existing drilling fluids fail to effectively protect high-permeability reservoirs due to the difficulty in accurately determining pore diameter distribution, leading to unsatisfactory temporary plugging and increased operation costs, as they require rigid granules that must match pore diameter for bridging, which is challenging in heterogeneous reservoirs.
Innovation Solution
A water-based drilling fluid containing polymeric elastic granules that can deform and adapt to different pore shapes, providing a high plugging success ratio without the need for plug removal, suitable for high-permeability reservoirs and resistant to high temperatures, suitable for deep and ultra-deep well drilling, and with excellent lubrication properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid granules of temporary plugging agent are used to plug pores by bridging, then temporary plugging effect is improved, but the dimensions of granules must match pore diameter accurately which is difficult in heterogeneous reservoirs, leading to low plugging success ratio
Solution Approach 1:
The patent changes the physical state parameter of the plugging agent from rigid to elastic deformable. The elastic granules can change their shape and size under stress, allowing them to adapt to various pore dimensions without requiring precise size matching. This parameter change enables the plugging agent to effectively plug pores across a range of diameters, significantly improving the plugging success ratio in heterogeneous reservoirs.
Solution Approach 2:
The patent introduces dynamic adaptability by using elastic granules that can deform under pressure. These granules dynamically adjust their shape and size to match the pore geometry they encounter, transforming from a static size-matching requirement to a dynamic adaptation process. This allows the same granule population to effectively plug pores of varying sizes and shapes.
2Reliability
If temporary plugging layer is formed to block drilling fluid from entering reservoir, then reservoir protection is improved, but oil and gas flow is blocked requiring plug removal work, increasing operation cost
Solution Approach 1:
The patent extracts the plugging function from a permanent or semi-permanent structure and makes it temporary and removable. The elastic granules form a plugging layer during drilling that can be easily removed after drilling completion. This separation of plugging function from permanent structure eliminates the need for complex plug removal operations while maintaining reservoir protection during the drilling process.
Solution Approach 2:
The patent employs disposable elastic granules that serve their plugging function temporarily during drilling and then can be easily removed or left to degrade. These granules are designed to be inexpensive and temporary, fulfilling the plugging requirement during drilling operations without creating long-term obstacles to oil and gas flow, thereby eliminating costly plug removal operations.
3Productivity
If drilling fluid infiltrates deeply into high-permeability reservoir, then drilling fluid can enter reservoir easily, but causes damages such as clay swelling, dispersed migration, and water blocking in greater scope
Solution Approach 1:
The patent applies preliminary action by forming a plugging layer at the pore entries before drilling fluid can infiltrate deeply into the reservoir. The elastic granules plug the pore entrances, creating a barrier that prevents or limits the infiltration of drilling fluid into the reservoir matrix. This preliminary plugging action occurs before significant damage can propagate into the reservoir, protecting the reservoir from clay swelling, dispersed migration, and water blocking.
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 water-based drilling fluid achieves a high plugging success ratio, maintains reservoir permeability, and reduces operation costs by allowing the plugging layer to be removed automatically, ensuring effective reservoir protection and efficient drilling processes across varying conditions.
Implementation Method 1
polymeric elastic granules that can deform and adapt to different pore shapes
Implementation Method 2
the intermediate product is prepared from raw materials including acrylamide, a cationic monomer, a cross-linker, an initiator
Data Source
AI summary
Disclosed herein are water-based drilling fluids for protecting high-permeability reservoirs. The drilling fluid comprises bentonite, a tackifier, a thinner, a filtrate reducer, an anti-collapse agent, a reservoir protectant, a lubricant, and water.