Reservoir Protecting Agent Composition for Middle Permeability Drilling
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Solution Overview
Problem
Conventional drilling fluids fail to provide adequate reservoir protection for middle permeability reservoirs, leading to reduced oil yield and increased resistance to air and gas flow due to improper design and interactions with clay and minerals, resulting in damage such as clay swelling and water blocking.
Innovation Solution
A reservoir protecting agent composition comprising non-fluorescent sulfonated asphalt and an amphiphilic polymer, which forms a plugging layer on the rock surface to prevent fluid intrusion and enhance mud cake quality, effectively protecting the reservoir from damage by forming a dense film and inhibiting hydrated expansion and dispersion of clay minerals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If drilling fluids are designed for low-permeability, high-permeability, or super-high-permeability reservoirs, then the drilling fluid can meet the requirements for those specific reservoir types, but the drilling fluid is not suitable for protection of middle permeability reservoirs and causes reservoir damage
Solution Approach 1:
The patent develops a drilling fluid system specifically tailored for middle permeability reservoirs (70-200 mD) with localized chemical composition and performance characteristics that differ from conventional drilling fluids designed for other permeability ranges. This includes specific polymer concentrations, pH ranges, and additive packages optimized for the unique pore structure and clay mineral content of middle permeability reservoirs, thereby achieving both adaptability to this specific reservoir type and reliable protection effectiveness.
Solution Approach 2:
The patent employs composite drilling fluid formulations combining multiple functional components including polymers, surfactants, and temporary plugging agents in specific ratios. This composite approach creates a drilling fluid system that simultaneously provides cuttings carrying capability, well wall stability, and reservoir protection for middle permeability reservoirs, resolving the contradiction between meeting operational requirements and providing specialized protection.
2Ease of operation
If conventional drilling fluid systems are used in middle permeability reservoirs, then the drilling fluid can carry cuttings and maintain well wall stability, but the reservoir protection effect is not ideal and core permeability recovery value is low
Solution Approach 1:
The patent incorporates temporary plugging agents that form preliminary plugs in the pore throats of the reservoir before significant filtrate invasion occurs. This preliminary action prevents or minimizes subsequent clay swelling, dispersion, and water blocking, thereby maintaining high permeability recovery values while preserving the operational performance of the drilling fluid for cuttings carrying and well wall stabilization.
Solution Approach 2:
The patent modifies key parameters of the drilling fluid system including pH control, polymer molecular weight distribution, and additive concentration ratios to optimize both operational performance and permeability recovery. By carefully adjusting these parameters, the drilling fluid achieves excellent rheological properties for drilling operations while simultaneously providing precise control over reservoir permeability preservation, achieving over 90% permeability recovery in middle permeability reservoirs.
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 drilling fluid with the reservoir protecting agent composition exhibits improved rheology, temperature tolerance, anti-collapse, and protection performance, significantly reducing reservoir damage and enhancing oil and gas recovery by maintaining permeability and preventing fluid intrusion, thus addressing the limitations of existing drilling fluids for middle permeability reservoirs.
Implementation Method 1
the reservoir protecting agent is composed of structural units denoted by the following formula (1), (2), and (3)... forms a plugging layer on the rock surface
Implementation Method 2
enhancing plugging performance and is suitable for middle permeability reservoirs... forms a dense film and inhibiting hydrated expansion and dispersion of clay minerals
Data Source
AI summary
The present subject matter discloses a reservoir protecting agent composition, consisting of non-fluorescent sulfonated asphalt and a reservoir protecting agent, wherein, the reservoir protecting agent is composed of structural units denoted by the following formula (1), (2), and (3). The present subject matter further provides a drilling fluid that contains the above-mentioned reservoir protecting agent composition for middle permeability reservoirs. The present subject matter further provides an application of the drilling fluid for middle permeability reservoirs in well drilling in middle permeability reservoirs. The drilling fluid for middle permeability reservoirs disclosed in the present subject matter exhibits favorable rheology property, temperature tolerance property, and anti-collapse and protection performance when it is used in wall drilling in middle permeability reservoirs.