Friction pressure loss analysis on typical hydraulic fracturing data

Abstract

The aim. High hydraulic friction in the tubing can cause premature shutdown of the hydraulic fracturing operation and costly repairs. Sudden changes in hydraulic friction of the fluid may indicate a failure of cross-linker, breaker or other additives, being an important diagnostic factor. Hydraulic fracturing modeling always includes the calculation of friction in the tubing using existing friction maps, which require constant updating. This paper presents the methodology and its implementation in a new engineering tool for friction analysis in “RN-GRID” fracturing simulation software, which makes it possible to reconstruct friction maps from actual hydraulic fracturing data.

Materials and methods. The proposed friction analysis technique requires actual data on flow rate and bottomhole and wellhead pressures. The entire interval of data has to be split into separate intervals of different fracturing fluids and proppants. The solution of the inverse friction model parameters problem yields friction maps of fluids, displacing one another in the wellbore. Each friction map is identified as a power-law dependence on the flow rate.

Results. The method was implemented as a new engineering analysis tool in “RN-GRID” fracturing simulation software. The method was tested on a number of fracturing jobs on vertical and horizontal wells. It successfully restores the parameters of the power-law friction model, returning the expected and reproducible results on 10 and 18 injections in two horizontal wells. The paper also provides limitations of the method and describes how injection plan can be altered to extract more information on hydraulic friction.

Conclusion. A new method of friction analysis makes it possible to identify friction maps of fluids involved in hydraulic fracturing without additional lab research, even while they replace each other in the wellbore during the injection. The friction correction model for the proppant can also be identified. The tool is intended for engineers’ use to update the friction maps of fracturing fluids.