Granite Waste Powder Lightweight Cement for Low Fracture Gradient Wells
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Solution Overview
Problem
Conventional oil-well cement systems are not suitable for formations with low fracture gradients as they impose high pressure and lead to formation breakdown, loss of cement slurry, and well integrity issues, necessitating a lightweight alternative with enhanced strength.
Innovation Solution
A method involving dry mixing of granite waste powder (GWP) with cement, adding it to an aqueous composition with sodium bentonite, calcium chloride, and perlite to create a ternary blend, which is injected into the well to seal and cure, achieving compressive strengths of 30,000 to 50,000 psi at 15,000 psi effective pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional oil-well cement systems are used, then the cement provides adequate strength, but it imposes high pressure on the formation leading to formation breakdown and loss of well integrity
Solution Approach 1:
The patent changes the density parameter of the cement system by incorporating lightweight fillers (diatomaceous earth, pumice, expanded clay, or perlite) to reduce the cement slurry density from conventional 15.6-16.4 ppg to 13.5-14.5 ppg. This parameter change allows the cement to provide adequate strength while imposing lower pressure on the formation, preventing formation breakdown in low fracture gradient formations.
Solution Approach 2:
The patent creates a composite cement system by combining Portland or pozzolanic cement with lightweight filler materials. This composite approach maintains the strength-providing properties of cement while incorporating low-density materials that reduce overall slurry density and pressure on the formation, thereby resolving the contradiction between strength and pressure.
2Stress or pressure
If filler materials are added to reduce cement slurry density, then the pressure on formation is reduced, but the health associated with filler material disposal becomes a concern
Solution Approach 1:
The patent converts the previously harmful waste products (diatomaceous earth, pumice, expanded clay, perlite) into beneficial lightweight filler materials that reduce cement slurry density. By incorporating these materials into the cement system, the invention eliminates the need for separate disposal of these fillers, as they become integral components of the cement slurry, thereby converting a harmful disposal issue into a beneficial density reduction solution.
3Strength
If two or more pozzolans/filler materials are admixed, then hardened composites with enhanced properties are achieved, but the complexity of the mixing process increases
Solution Approach 1:
The patent merges multiple pozzolans and filler materials into a single integrated cement slurry formulation. By combining Portland or pozzolanic cement with lightweight fillers and appropriate chemical additives in one mixing process, the invention achieves enhanced hardened composite properties without requiring separate mixing operations, thereby reducing overall process complexity while maintaining strength enhancement.
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 method provides a lightweight cement system with improved compressive strength and reduced pressure impact, effectively sealing the well while addressing health concerns associated with filler material disposal and enhancing long-term strength development.
Implementation Method 1
The GWP has a pozzolanic reaction with the cement during the curing producing a strength activity of from 100% to 110% compared to the cement
Data Source
AI summary
A method for treating a well in a hydrocarbon-producing subterranean production zone. The method for treating well-producing hydrocarbons from a subterranean production zone includes dry mixing a granite waste powder (GWP) in a form of rock aggregates and a cement to form a mixture. Then the mixture is added to the cement composition containing water, pre-hydrated sodium bentonite, calcium chloride, a dispersant, and an alcohol-based defoamer to form a cement slurry. The cement slurry is prepared at a density of from 13.5 pounds per gallon (ppg) to 14.5 ppg and contains the GWP in a range of from 5 wt. % to 20 wt. % of the cement slurry. 10 wt. % to 15 wt. % perlite is added into the cement slurry to form a ternary blend which is cured and then the cured product is injected into the well to seal the well at the subterranean production zone.