Oil-Based Sorel Cement for Water-Sensitive Wellbore Isolation
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Solution Overview
Problem
Existing wellbore servicing technologies face challenges with fluid loss and incompatibility with oleaginous fluids, particularly in formations sensitive to water, leading to ineffective zonal isolation and damage to subterranean formations.
Innovation Solution
A method using a composition comprising magnesium oxide, a soluble salt, an organophilic surfactant, and an oleaginous fluid, which sets to form a Sorel cement that is compatible with oleaginous fluids, preventing fluid loss and providing effective zonal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-based Sorel cement compositions are used to plug lost circulation zones, then effective plugging and zonal isolation are achieved, but formations sensitive to water (containing swelling clay and shales) suffer damage and sloughing
Solution Approach 1:
The patent changes the fundamental parameter of the cement composition by replacing water-based formulations with oil-based Sorel cement compositions. This parameter change allows the cement to provide effective plugging functionality while eliminating the harmful water contact with sensitive formations, thereby resolving the contradiction between plugging effectiveness and formation protection
Solution Approach 2:
The patent creates a composite material system combining Sorel cement with oil-based fluids and compatible additives. This composite approach enables the cement to maintain its plugging and zonal isolation capabilities while the oil-based matrix prevents formation damage, simultaneously achieving both competing objectives
2Object-affected harmful factors
If oleaginous fluids are used in water-sensitive formations, then formation damage is prevented, but compatibility with Sorel cement compositions becomes problematic
Solution Approach 1:
The patent changes the base fluid parameter from water to oil, creating an oil-based Sorel cement composition. This parameter change fundamentally alters the chemical compatibility profile, allowing the use of oleaginous fluids in water-sensitive formations while maintaining cement functionality through careful formulation with compatible additives
Solution Approach 2:
The patent develops a composite oil-based Sorel cement system that integrates Sorel cement particles with oil-based fluids and specialized additives. This composite structure achieves both formation protection and cement reliability by creating a chemically compatible system where oil replaces water as the continuous phase
3Loss of substance
If conventional plugging materials (walnut hulls, mica, cellophane) are used to prevent fluid loss, then fluid loss is reduced, but the materials cannot be removed and may dislodge causing resumed fluid loss
Solution Approach 1:
The patent employs Sorel cement as a temporary, sacrificial plugging material that fulfills its function of preventing fluid loss during drilling operations and then dissolves away when no longer needed. This disposable approach allows effective fluid loss prevention during the critical drilling phase while eliminating the long-term complications of permanent plugging materials
Solution Approach 2:
The patent implements a strategy where the Sorel cement plug is intentionally designed to be discarded (dissolved) after serving its purpose. The cement is placed to prevent fluid loss during drilling, then later removed by dissolution when the wellbore is ready for subsequent operations, achieving both effective temporary plugging and clean removal without formation damage
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 solution effectively prevents fluid loss and ensures strong zonal isolation, maintaining the integrity of subterranean formations by forming a rigid mass with appreciable compressive strength, suitable for use in challenging drilling conditions.
Implementation Method 1
a composition comprising a metal oxide, a soluble salt, a surfactant and an oleaginous fluid
Implementation Method 2
Sorel cement compositions typically comprise magnesium oxide and a chloride or phosphate salt and water which together form for example magnesium oxychloride
Data Source
AI summary
A method of servicing a wellbore in contact with a subterranean formation comprising placing in the wellbore a composition comprising a metal oxide, a soluble salt, a surfactant and an oleaginous fluid, and allowing the composition to set. A method of cementing a wellbore comprising placing a first composition comprising magnesium oxide, a chloride or phosphate salt, an organophilic surfactant and an oleaginous fluid into a wellbore, allowing the composition to set, placing a second cementitious composition into the wellbore, and allowing the second cementitious composition to set. A method of servicing a wellbore comprising placing in the wellbore a composition comprising magnesium oxide, magnesium chloride, an organophilic surfactant, water and an oleaginous fluid wherein the organophilic surfactant is present in an amount of from about 0.25% to about 5% base on the combined weight of the magnesium oxide and magnesium chloride, and the oleaginous fluid is present in a ratio of from about 95:5 cement:oleaginous fluid to about 50:50 cement:oleaginous fluid.