INFLUENCE OF RESERVOIR PROPERTIES OF THE BOTTOMHOLE ZONE ON ACIDIZING EFFICIENCY

Abstract

Relevance. Currently, a large amount of research is directed on optimization of well operation. It is associated with the study of the effect of injection rate of acidizing on the nature of formation of channels and determination of optimal injection volumes. One of the important factors is the initial state of the bottomhole zone: permeability, saturation of reservoir fluids, contaminate of the drilling fluid. The main aim of this work is to assess the effect of the initial filtration characteristics of the bottomhole zone on acidizing efficiency. Methods. Several experiments were performed simulating the acidizing. Samples with different reservoir properties were used. A number of experiments modeling contamination of samples with drilling mud were performed. Results. It was found that under equal conditions the core samples with low permeability has better efficiency with acidizing in comparison with highly permeability cores. Larger amount of hydrochloric acid solution is required to create breakthrough channels in low-permeable reservoirs. The equivalent surface of the channels allows evaluating the effectiveness of acidizing. The equivalent surface of acid-formed channels is higher for the samples with low permeability. The effect of acidizing for cores contaminated with the drilling fluid and low-permeable cores is equal. The results obtained can be used in acidizing in the field with a high probability of a positive effect. In the future, it is necessary to give an economic assessment, taking into account the time of formation of breakthrough channels and the required amount of HCl acid.

Keywords

• acidizing
• damkeller number
• porosity
• permeability
• reaction rate
• core sample