Method for preparing fluid gel by utilizing formation temperature to form blocking valve to block air layer

Abstract

The invention discloses a method for preparing fluid gel by utilizing a formation temperature to form a blocking valve to block an air layer. The method comprises the following steps: a, preparing a stirrer; b, adding water into the stirrer, starting an impeller in the stirrer at normal temperature, and stirring the water; c, adding an initiation monomer and a cross-linking monomer while stirring the water, adding a gel initiator after the added initiation monomer and cross-linking monomer are dissolved, and continuously stirring to form gel blocking fluid; and d, pumping the gel blocking fluid into a shaft at projected depth to form fluid gel, wherein the water, the initiation monomer and the cross-linking monomer form a gel cross-linking system, the ratio of weight parts of the gel cross-linking system to the gel initiator is (10-30):1, and based on the total mass percentage of the formed fluid gel, the added initiation monomer accounts for 2-15 percent, the cross-linking monomer accounts for 0.1-5 percent, the gel initiator accounts for 0.1-2 percent, and the rest is water. The process is simple, and the prepared fluid gel is low in cost and has extremely high pressure resistance.

Description

[0001] technical field [0002] The invention relates to a method for preparing a fluid used to form a gel isolation valve to seal an oil and gas layer by using formation temperature. The prepared fluid gel is especially suitable for an oil and gas reservoir as a casing valve to form an isolation area between the reservoir and the ground , It is convenient for low-pressure operations such as wellhead disassembly and assembly. Background technique [0003] In the process of wellhead construction in medium and low pressure reservoirs, in order to prevent formation fluids (oil, gas, water) from gushing out of the wellhead and cause danger, mechanical packers are often lowered and installed in the wellbore at a certain depth, between the wellbore and the surface. Form a blockage between them, which is convenient for wellhead construction operations. [0004] At present, the price of mechanical casing valves used is relatively high, and the equipment is mainly imported. The d...

AI Technical Summary

Problems solved by technology

[0007] 1. The existing gel preparation process is relatively complicated, the cost of the prepared gel is relatively high, and the pressure resistance and airtightness are not enough;

[0008] 2. The existing gel formula has poor water retention performance after being gelled, and lacks better water retention monomers in the gel;

[0009] 3. The cross-linking agent only uses potassium persulfate or ammonium persulfate, which belongs to the water-soluble inorganic peroxygen gel initiator. This type of initiator is greatly affected by temperature, that is, the reaction must be initiated at a certain temperature and the reaction is easy to occur. Inhomogeneous gel, local dehydration