Research on low-damage workover fluid for low-pressure gas well

Well workover is a work of rescinding faults and improving borehole conditions so as to restore the normal production of oil and gas wells and reservoir damage occurs because of the mismatch of workover fluids with the fluids and minerals in reservoir and of the oversize filtration of the workover fluids. By taking the well Wei-126 as an example, the optimization of low-damage workover fluids for low-pressure gas wells was studied in detail. In light of the reservoir characteristics, as high temperature, high permeability, strong water sensitivity and strong salt sensitivity, etc., to raise the salinity of workover fluid to 12.5%, a workover fluid formulation TC2-5 with good performance was developed through the filtration screening experiment of organic heat-resisting and salt-resisting filtrate reducer, the experiment of core damage and the evaluation experiment of the surface tension of filtrate of the workover fluid, and it was successfully applied to the workover operation in the well Wei-126 and a good application effect was obtained, i. e. carrying out a balanced pressure workover with low damage.