Experimental Research on Rheological Properties and Proppant Transport Performance to Optimise Carbon Dioxide Fracturing Fluid Systems
MCLAUGHLIN, Jarryd, NAIDU, Viv, VENNER, Bradley
Engineering Honours 2015
Australian School of Petroleum
University of Adelaide
Hydraulic fracturing is a vital stimulation technique that enhances recovery in formations that would otherwise be considered uneconomical. The selection of hydraulic fracturing fluid is highly dependent on sub-surface thermal and pressure conditions as the molecular integrity of these fluids typically degrade with increasing temperatures and pressures. Developments in Carbon dioxide (CO2) foam-based fracturing fluids have benefited the industry and are widely documented. The research pertaining to this report eludes that a CO2 foam fracturing fluid has not been developed for high pressure high temperature (HPHT) environments such as the Cooper Basin. There is minimal research justification as to why this is the case.
This report aims to design an experimental laboratory scale apparatus to investigate the reasons behind unsuccessful fracturing fluid generation under HPHT. Possible reasons include inadequate viscosities and instability of foams as a result of increasing pressure and temperature. If laboratory scale testing is successful, promotion to field scale testing is sanctioned. This could promote a fracturing fluid to be tailored to suit the conditions displayed by the Cooper Basin. In addition, base testing of fracturing fluid to determine the rheological properties was undertaken and performance of proppant transport abilities was predicted. These aspects are key considerations when designing an overall optimal fracturing fluid system.
In order to determine an optimum fracturing fluid that will be suitable for reservoir conditions similar to that of the Cooper Basin, this project was divided into three parts: base case testing, experimental design and proppant transport prediction. Methodologies presented by the industry sponsor were implemented to test the base case fluid. Results were later incorporated into the Modified Stokes law to predict proppant settling velocities. An iterative approach was adopted for the practical design of the experimental set-up. Knowledge from industry support, academia, the literature and manufactures were pivotal.
This thesis concluded that a laboratory scale design for a CO2 fracturing fluid system under HPHT conditions, with proposed investigations into optimising this system, is to be conducted at the ASP. The effects of temperature to cause fluid degradation were found to be more dominant over the effects of pressure due to secondary chemical reactions. Proppant transport abilities corresponding to the base fluid were deemed adequate at lower temperatures, but were compromised at higher temperatures. This project has potential to contribute to the experimental research conducted at the ASP and also withholds potential to benefit unconventional reservoirs, which are becoming increasingly attractive with advances in fracture stimulation technologies.