Settable, form-filling loss circulation control compositions comprising in situ foamed non-hydraulic sorel cement systems and method of use
This document relates to settable, non-hydraulic foamed cement compositions comprising nitrogen gas-generating compositions used for loss circulation control.
1. A foamed cementitious composition, comprising:
magnesium oxide (MgO);
magnesium chloride hexahydrate (MgCl 2 .6H 2 O);
a nitrogen gas-generating compound; and
a foam surfactant.
2. The composition of claim 1 , wherein the foam surfactant is selected from the group consisting of an alkyl sulfate salt with a C 12 -C 14 carbon chain, a betaine, and a hydroxysultaine.
3. The composition of claim 2 , wherein the foam surfactant is cocoamidopropyl hydroxysultaine.
4. The composition of claim 1 , wherein the nitrogen gas-generating compound is an azo compound.
5. The composition of claim 4 , wherein the azo compound is azodicarbonamide.
6. The composition of claim 4 , wherein the azo compound is about 1% to about 10% by weight of the MgO.
7. The composition of claim 4 , further comprising an amine activator selected from the group consisting of carbohydrazide (CHZ), tetraethylenepentamine (TEPA), and hydrazine sulfate.
8. The composition of claim 7 , wherein the weight ratio of the azo compound to the amine activator is about 5:1 to about 1:5.
9. The composition of claim 7 , wherein the amine activator is CHZ.
10. The composition of claim 9 , wherein the composition further comprises an oxidizer.
11. The composition of claim 1 , further comprising a set retarder selected from the group consisting of hexametaphosphate, sodium borate, sodium citrate, citric acid, and an aminophosphonate.
12. The composition of claim 1 , further comprising a viscosifier.
13. The composition of claim 1 , wherein the pH of the foamed cementitious composition is greater than about 4.