Phosphate Cement Thickening Time via Borate Sugar Synergy

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Solution Overview

Problem

Phosphate-based cementitious compositions used in well cementing set too quickly, especially at high temperatures, making it challenging to pump them to desired downhole locations without cementing drill pipes in place, resulting in delays.

Innovation Solution

Incorporating a borate compound and a sugar into phosphate-based cementitious compositions, which synergistically increases the thickening time from 2 to 11 hours at ambient temperatures, allowing for proper placement before setting, even at high temperatures and pressures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If phosphate-based cementitious compositions are used to achieve quick setting and strong binding, then the cement sets rapidly and binds well to formation and itself, but the thickening time becomes unacceptably short making it difficult to pump to desired locations

Engineering Contradiction:

Improvebinding strengthVSAvoidthickening time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

A borate compound is introduced as an intermediary substance that mediates between the metal oxide and phosphate compound. The borate compound forms a complex with the metal oxide, preventing direct rapid reaction with the phosphate compound, thereby extending thickening time while maintaining final binding strength.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The reaction kinetics are modified by changing the chemical environment through borate addition. The borate compound alters the reactivity parameters of the system, reducing the initial reaction rate to extend pumpable time while preserving the ultimate strength development of the cement.

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If boric acid or salts are introduced to lengthen thickening time to 3-4 hours at low temperatures, then the thickening time increases, but the thickening time remains insufficient at higher temperatures for proper downhole placement

Engineering Contradiction:

Improvethickening timeVSAvoidtemperature sensitivity

Core Design Contradiction:

Loss of timeVSTemperature

Solution Approach 1:

The cement composition is formulated as a composite system containing metal oxide, phosphate compound, and borate compound in specific proportions. This composite formulation creates a synergistic effect where the borate compound provides temperature-dependent retardation, extending thickening time to 4-12 hours even at elevated downhole temperatures.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The chemical composition parameters are optimized by selecting specific ratios of metal oxide to phosphate compound and incorporating borate compound at controlled levels. This parameter optimization ensures the cement maintains adequate thickening time across a range of temperatures from ambient to high downhole conditions.

Inventive Principle:

Principle #35Parameter changes

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 combined use of a borate compound and sugar significantly extends the thickening time of phosphate-based cementitious compositions, enabling them to be pumped and placed effectively in wellbores with high temperatures and pressures, reducing the risk of premature setting and associated delays.

Implementation Method 1

The synergistic effect of the borate compound and the sugar may increase a thickening time of the cementitious composition to in a range of from about 2 hours to about 11 hours at ambient temperatures in the wellbore

Methodology Applied

Scientific EffectChemical reaction inhibition:

Implementation Method 2

The metal oxide or hydroxide compound reacts with the phosphate compound in the wellbore to set into a hard mass

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS7527098B2Methods of increasing the thickening times of phosphate-based cementitious compositions in high-temperature wellbores

Publication Date: 2009.05.05 HALLIBURTON ENERGY SERVICES INC

AI summary

A wellbore may be cemented by preparing a cementitious composition comprising water, a metal oxide or hydroxide compound, a phosphate compound, a borate compound, and a sugar, followed by displacing the cementitious composition into the wellbore. The metal oxide or hydroxide compound reacts with the phosphate compound in the wellbore to set into a hard mass. The synergistic effect of the borate compound and the sugar may increase a thickening time of the cementitious composition to in a range of from about 2 hours to about 11 hours at ambient temperatures in the wellbore. As such, the thickening time is sufficient to allow the cementitious composition to be placed in its desired location in the wellbore before setting.