Acid strength determination method for washing horizontal water injection well

The invention discloses an acid strength determination method for washing a horizontal water injection well and belongs to the technical field of petroleum and gas exploration. The method is characterized by comprising the following steps of a, fitting an acid strength index AS by means of acid consumption per meter after historical well washing; b, calculating a historical pickling well pressurechange rate Rcip by means of historical production data, and classifying the acid strength index according to amplitude of the historical pickling well pressure change rate Rcip to establish a targetresearch area Rcip-AS classifying model; c, calculating a pressure change rate Rcip by means of target research area production data and drawing a pressure change rate Rcip curve of a full life circle; and d, predicting the acid strength index AS in different pressure change rate Rcip grades. The method can determine the acid strength reasonably, avoid waste of working hours and materials due to too high or too low acid st