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 method of treating a lost circulation zone, the method comprising:
a) forming 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;
an oxidizer;
a nitrogen gas-generating compound; and
a foam surfactant; and
b) introducing the foamed cementitious composition into the lost circulation zone.
2. The method of claim 1 , wherein the nitrogen gas-generating compound is an azo compound, and wherein the salt is magnesium chloride hexahydrate (MgCl 2 .6H 2 O).
3. The method of claim 2 , wherein the azo compound is about 1% to about 10% by weight of the MgO.
4. The method of claim 2 , further comprising an amine activator selected from the group consisting of carbohydrazide (CHZ), tetraethylenepentamine (TEPA), and hydrazine sulfate.
5. The method of claim 4 , wherein the weight ratio of the azo compound to the amine activator is about 5:1 to about 1:5.