Evaluation Of The Performance And Adaptability Of Unblocking And Unwaterlocking Agents For Shut-in Wells In The Surig Gas Field And Their Application

Some of the gas wells in the Surig gas field have now reached the middle and late stages of development.Due to the geological characteristics of the reservoir itself and the different degrees of damage caused to the reservoir during different operations,some of the Surig gas wells are in shutdown status.In order to restore gas well production,the Surig gas field has introduced reservoir unblocking and unwaterlocking agent to resume production,but there is no unified evaluation method for unblocking and unwaterlocking agents,resulting in multiple evaluations by oilfield units.This paper investigates the existing methods of unblocking and unlocking agents,determines the evaluation method of unblocking and unlocking agents,evaluates the performance and unblocking and unlocking effect of unblocking and unlocking agents put into shut-in wells in Surig,and determines the recommended index of unblocking and unlocking agents by combining the actual production situation of shut-in wells before and after the introduction of unblocking and unlocking agents.A comparison was made with the performance of the agents in the field.The main conclusions from the above study are as follows:(1)Blockages mainly consisting of calcium carbonate,barium sulphate and corrosion products exist in the shut-in wells of Surig,and eight shut-in wells have an APTi index basically within 0.3,showing strong production characteristics of water-locked wells,indicating that the main cause of the low-production shut-in wells of Surig is solid-phase blockage and water-lock damage.(2)There is a correlation between the effect of unblocking and hydrolocking agent treatment and capillary force.The capillary force of cores treated with unblocking and hydrolocking agent all decreased,and the lower the capillary force,the smaller the amount of self-absorbed fluid in the core,the greater the capillary bound water change ratio,and the greater the recovery rate of gas-liquid phase permeability,i.e.the better the effect of unblocking and hydrolocking.There is a linear relationship between capillary force and σcosθ,which is consistent with the capillary force formula.(3)Unblock and unlock agent SUG-01 consists of 0.005% SU-FT-2 + 10% ethylene glycol+ 10% ethylene glycol butyl ether + 6% HCl + 2% HF + 5% CH3 COOH + 0.5% JBX-2,compared with the field use of unblock and unlock agent,has a lower surface tension and stronger wetting reversal effect,about 5400 yuan per tonne cheaper.It has better economy.(4)High efficiency unblock and unlock agent corrosion rate is less than 2mm/a,no pitting;good compatibility with formation water and other foreign fluids;scale dissolution rate is greater than 75% for gas well blockage;lower surface tension,wetting reversal ability,the lower the value of σcosθ the better;formation water permeability recovery rate is greater than 70%,gas phase permeability recovery rate is greater than 50% after treatment by unblock and unlock agent The reservoir water permeability recovery rate is greater than 70% and the gas phase permeability recovery rate is greater than 50% after treatment with unblocking and unwaterlocking agent.