Cross-linked plugging agent stimulated by high density brine and preparing method thereof

Abstract

The present invention disclosed a cross-linked plugging agent stimulated by high density brine which comprises main agent: 10 wt %-90 wt %, gelling agent: 0.5 wt %-9 wt % and pure water; wherein the main agent is selected from the group consisting of a Dipotassium phosphate (K 2 HPO 4 ), a Tripotassium phosphate (K 3 PO 4 ) and a Potassium pyrophosphate (K 4 P 2 O 7 ), a Potassium Dihydrogen Phosphate (KH 2 PO 4 ), a Sodium dihydrogen phosphate (NaH 2 PO 4 ); the gelling agent is selected from the group consisting of a Xanthan gum and a kappa carrageenan. The gelling time is controlled within 0.5-12 h under an experiment temperature of 90° C.-160° C. The final gelling strength is controlled within D-H. The density is controlled within 1.0-1.55 g/cm 3 . The plugging agent is able to be applied in well completion and workover under high temperature, high pressure, multi-pressure series of strata oil and gas environment when temporary blockage and leak proof is required, protection of reservoir near perforations and water plugging.

What is claimed is: 
     
         1 . A cross-linked plugging agent stimulated by high density brine, comprising:
 main agent: 10 wt %-90 wt %, gelling agent: 0.5 wt %-9 wt % and pure water; wherein the main agent is selected from the group consisting of a Dipotassium phosphate (K 2 HPO 4 ), a Tripotassium phosphate (K 3 PO 4 ) and a Potassium pyrophosphate (K 4 P 2 O 7 ) a Sodium dihydrogen phosphate (NaH 2 PO 4 ); wherein the gelling agent is selected from the group consisting of a Xanthan gum and a kappa carrageenan.   
     
     
         2 . The cross-linked plugging agent stimulated by high density brine, as recited in  claim 1 , further comprising main agent of 30 wt %-70 wt %. 
     
     
         3 . The cross-linked plugging agent stimulated by the high-density brine, as recited in  claim 1 , wherein the main agent further comprises a Potassium Dihydrogen Phosphate (KH 2 PO 4 ) and a Sodium dihydrogen phosphate (NaH 2 PO 4 ). 
     
     
         4 . The cross-linked plugging agent stimulated by the high-density brine, as recited in  claim 1 , wherein a density of the plugging agent is controlled within 1.0-1.55 g/cm 3 . 
     
     
         5 . A method of preparing a cross-linked plugging agent stimulated by high density brine, comprising following steps of:
 adding main agent, gelling agent into pure water in sequence with respective percentage by mass; stirring evenly; setting an experiment temperature at 90° C.-160° C.; and determining a gelation time and a gelation strength of the plugging agent by gel strength codes; wherein the main agent is 10 wt %-90 wt % and the gelling agent is 0.5 wt %-9 wt %, wherein the main agent is selected from the group consisting of a Dipotassium phosphate (K 2 HPO 4 ), a Tripotassium phosphate (K 3 PO 4 ) and a Potassium pyrophosphate (K 4 P 2 O 7 ); wherein the gelling agent is selected from the group consisting of a Xanthan gum and a kappa carrageenan.   
     
     
         6 . The method of preparing a cross-link plugging agent stimulated by high density brine, as recited in  claim 4 , wherein the main agent is further of 30 wt %-70 wt %. 
     
     
         7 . The method of preparing a cross-link plugging agent stimulated by high density brine, as recited in  claim 4 , wherein the main agent further comprises a Potassium Dihydrogen Phosphate (KH 2 PO 4 ), a Sodium dihydrogen phosphate (NaH 2 PO 4 ). 
     
     
         8 . The method of preparing a cross-linked plugging agent stimulated by high density brine, as recited in  claim 3 , wherein a density of the plugging agent is controlled within 1.0 g/cm 3 -1.55 g/cm 3 . 
     
     
         9 . A method of applying a cross-linked plugging agent stimulated by the high density brine, comprising a step of applying the plugging agent in well completion and workover under high temperature, high pressure, multi pressure series of strata oil and gas environment when temporary blockage and leak proof is required, protection of reservoir near perforations and water plugging; wherein the cross-linked plugging agent stimulated by the high density brine comprises main agent which is 10 wt %-90 wt %, gelling agent which is 0.5 wt %-9 wt % and pure water, wherein the main agent is high density brine; wherein the main agent is selected from the group consisting of a Dipotassium phosphate (K 2 HPO 4 ) and a Tripotassium phosphate (K 3 PO 4 ) and a Potassium pyrophosphate (K 4 P 2 O 7 ); wherein the gelling agent is selected from the group consisting of a Xanthan gum and a kappa carrageenan. 
     
     
         10 . The method of preparing a cross-link plugging agent stimulated by high density brine, as recited in  claim 7 , wherein the main agent further comprises a Potassium Dihydrogen Phosphate (KH 2 PO 4 ), a Sodium dihydrogen phosphate (NaH 2 PO 4 ). 
     
     
         11 . The method of applying a cross-linked plugging agent stimulated by the high density brine, as recited in  claim 5 , comprising a step of applying the plugging agent in well completion and workover under high temperature, high pressure, multi pressure series of strata oil and gas environment when temporary blockage and leak proof is required, protection of reservoir near the perforations and water plugging; wherein a density of the plugging agent is controlled within 1.0-1.55 g/cm 3 .