High-Density Polymer Drilling Fluid for 240°C and Saturated Salinity
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Solution Overview
Problem
Existing water-based drilling fluids are unable to simultaneously meet the requirements of ultra-high temperature resistance, ultra-high pressure resistance, saturated salt resistance, and environmental protection, making them inadequate for drilling in deep and ultra-deep oil and gas formations.
Innovation Solution
A high-density, environmentally friendly polymer water-based drilling fluid is developed, comprising a micro-crosslinked heterocyclic polymer filtrate reducer, a hyper-branched strongly adsorbed polymer filtrate reducer, a nanometer intercalated complex shearing potentiator, and a flexible outer and rigid inner microsphere plugging agent, which maintains desirable properties for over 10 days under conditions of 240°C, saturated salinity, and high mineralization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional water-based drilling fluids are used, then environmental protection is improved, but temperature resistance deteriorates (cannot resist 240°C)
Solution Approach 1:
The patent uses composite polymers including crosslinked polyacrylamide and partially hydrolyzed polyacrylonitrile in specific ratios (0.5-5% and 1-10% respectively) to create a water-based drilling fluid that maintains environmental friendliness while achieving 240°C temperature resistance. The composite structure allows the fluid to withstand ultra-high temperature without compromising biodegradability.
Solution Approach 2:
The patent modifies key parameters including pH (maintained at 8-10 through sodium hydroxide addition), polymer concentration ratios, and crosslinking degree to enable the water-based fluid to resist 240°C. The controlled partial hydrolysis of polyacrylonitrile (30-70% degree) creates optimal thermal stability while preserving environmental compatibility.
2Weight of stationary object
If high density (2.4 g/cm³) is achieved, then drilling depth capability is improved, but fluid stability deteriorates under ultra-high temperature and salinity
Solution Approach 1:
The patent applies different functional polymers to different aspects of fluid performance: crosslinked polyacrylamide (0.5-5%) provides density maintenance and suspension capability for high-density requirements, while partially hydrolyzed polyacrylonitrile (1-10%) provides thermal and salinity stability. This localized functional assignment allows the fluid to maintain 2.4 g/cm³ density with stable composition under 240°C and saturated salt conditions.
Solution Approach 2:
The patent ensures continuous protective action through polymers with prolonged action time (≥72 hours at 240°C). The crosslinked structure and partial hydrolysis create a stable polymer network that continuously maintains fluid properties including density and stability throughout the drilling operation, preventing degradation under ultra-high temperature and salinity.
3Temperature
If sulfonated materials are added to improve temperature resistance, then temperature resistance is improved, but environmental protection performance deteriorates
Solution Approach 1:
The patent extracts and eliminates sulfonated materials from the drilling fluid system while achieving 240°C temperature resistance through alternative polymer chemistry. The solution uses crosslinked polyacrylamide and partially hydrolyzed polyacrylonitrile with carboxyl and amide groups instead of sulfonated polymers, maintaining thermal stability without compromising environmental protection performance.
Solution Approach 2:
The patent replaces expensive and environmentally harmful sulfonated materials with cost-effective, biodegradable polymer combinations. The crosslinked polyacrylamide and partially hydrolyzed polyacrylonitrile system provides equivalent or superior temperature resistance at lower cost with full environmental compatibility, enabling safe disposal after use.
4Stability of the object's composition
If high mineralization resistance is achieved, then salt resistance is improved, but rheology control deteriorates
Solution Approach 1:
The patent creates a dynamic rheological system where the polymer network adapts to salt concentration changes. The crosslinked polyacrylamide and partially hydrolyzed polyacrylonitrile form a flexible gel structure that maintains optimal viscosity and flow properties across varying salt conditions (including saturated NaCl). The pH control (8-10) dynamically adjusts polymer charge states to optimize both salt resistance and rheology simultaneously.
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 effectively reduces filtrate loss, maintains good rheology, and suspends weighting materials and drill cuttings for an extended period, preventing well accidents such as collapse, leakage, and blowout, while also being environmentally friendly and easy to maintain.
Implementation Method 1
a micro-crosslinked heterocyclic polymer filtrate reducer
Implementation Method 2
micro-crosslinked heterocyclic polymer
Implementation Method 3
hyper-branched strongly adsorbed polymer filtrate reducer
Implementation Method 4
nanometer intercalated complex shearing potentiator
Implementation Method 5
shearing potentiator
Implementation Method 6
suspends weighting materials and drill cuttings
Implementation Method 7
flexible outer and rigid inner microsphere plugging agent
Data Source
AI summary
The present disclosure relates to the technical field of drilling fluid, and discloses a high density environmentally friendly polymer water-based drilling fluid with resistance to 240° C. and saturated salts, a preparation method therefor and use thereof. The water-based drilling fluid comprises a micro-crosslinked heterocyclic polymer filtrate reducer, a hyper-branched strongly adsorbed filtrate reducer, a nanometer intercalated complex shearing potentiator, a flexible outer and rigid inner microsphere plugging agent, and water, wherein the micro-crosslinked heterocyclic polymer filtrate reducer is prepared by reacting sodium p-styrene sulfonate, N,N,N-trimethyl-3-(2-methylallylamino)-1-propyl ammonium chloride, N,N-diethyl acrylamide, N-vinyl caprolactam, tetramethyl ethylenediamine with phenyl triethoxy silane. The high density environmentally friendly polymer water-based drilling fluid with resistance to 240° C. and saturated salts of the present disclosure can exhibit good performance at high temperature and high salinity conditions, and has desirable weighting capability, it can meet the requirements of drilling well in the deep oil and gas formations.