New method for forming manual well wall in oil and gas well by water-absorbing resin

Abstract

The invention relates to a new method for forming manual well walls in an oil and gas wells by water-absorbing resin. In the method, the water-absorbing resin is mixed with freshwater or saline to form a well completion fluid or a workover fluid; the water-absorbing resin is starch-type water-absorbing resin or cellulose-type water-absorbing resin or synthetic water-absorbing resin and comprises the following components by weight percentage: 1 to 2% of water-absorbing resin, 0.2 to 0.5% of water-absorbing initiator, 0.2 to 0.5% of colloid protective agent, and the remaining quantity of water or monovalent saline. The density of the water-absorbing resin well-completion fluid or the workover fluid can be adjusted by adding monovalent salt NaCl or KCl; the solution apparent viscosity can be controlled by adjusting the concentration of the water-absorbing resin; and the dosage of the well completion fluid or the workover fluid can be designed according to the volume of a shaft. In the method, the physical and the chemical changes can occur under the high temperature to form a manual well wall, namely a gelatine temporary plugging layer; therefore, the bearing capability of the high-and low-pressure stratum can be effectively improved; the leakage of the well completion fluid or the workover fluid can be prevented at the producing layer, the operation safety and the capacity of the oil and gas well can be ensured, the construction technology is simple, and the cost is relatively low.

Description

technical field [0001] The invention relates to an artificial well formed in oil and gas wells by using water-absorbing resin in order to protect reservoirs, reduce production costs, and shorten construction period in well completion and workover operations of oil and gas wells in under-injection or depleted development oil and gas reservoirs. New way to wall. Background technique [0002] Many oil and gas fields in my country have entered the middle and late stages of development. Due to under-injection or depletion development, the formation pressure gradient of the main production layers has been much lower than the original formation pressure gradient, and may even be lower than the water column pressure. In this case, if oil and gas wells are to be completed and worked over, during the operation, a large number of completion fluids and workover fluids will inevitably be lost and solid relative to the productive layer will be blocked, making the oil and gas well after op...

Images