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);
a salt selected from the group consisting of magnesium chloride (MgCl 2 ), magnesium sulfate (MgSO 4 ), ammonium hydrogen phosphate (NH 4 H 2 PO 4 ), and hydrates thereof;
a nitrogen gas-generating compound;
a foam surfactant; and
an oxidizer.
2. The composition of claim 1 , wherein the salt is magnesium chloride hexahydrate (MgCl 2 .6H 2 O).
3. 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.
4. The composition of claim 3 , wherein the foam surfactant is cocoamidopropyl hydroxysultaine.
5. The composition of claim 1 , wherein the nitrogen gas-generating compound is an azo compound.
6. The composition of claim 5 , wherein the azo compound is azodicarbonamide.
7. The composition of claim 5 , wherein the azo compound is about 1% to about 10% by weight of the MgO.
8. The composition of claim 5 , further comprising an amine activator selected from the group consisting of carbohydrazide (CHZ), tetraethylenepentamine (TEPA), and hydrazine sulfate.
9. The composition of claim 8 , wherein the weight ratio of the azo compound to the amine activator is about 5:1 to about 1:5.
10. The composition of claim 8 , wherein the amine activator is CHZ.
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.