Fracturing and Reservoir Fluid Systems

**19**

**Chapter 2**

**Abstract**

CO2 Foam as an Improved

Unconventional Reservoir

*Shehzad Ahmed, Alvinda Sri Hanamertani* 

*and Muhammad Rehan Hashmet*

Fracturing Fluid System for

the performance of CO2 foam as an improved fracturing fluid system.

Global energy consumption has been increasing rapidly whilst existing oil and gas fields are being depleted day by day. In addition, insufficient amount of hydrocarbons produced from conventional reservoirs to fulfill the increasing energy demand has led to global challenges. Due to these factors and also environmental reasons, the use of natural gas that is considered as a green energy, is demanding. The large volume of natural gas stored in tight formation such as shale and tight sand has been practically developed recently. According to the report of EIA Annual

Energy Outlook 2015, the total energy consumption in 2040 will rise to 105.7 quadrillion Btu from 97.1 quadrillion Btu which is about 8.9% of the total energy

**Keywords:** fracturing fluid, shales, CO2 foam, foam rheology

**1. Introduction to unconventional reservoirs**

Unconventional reservoirs have gained substantial attention due to huge amount of stored reserves which are challenging to produce. Innovative recovery techniques include horizontal drilling coupled with hydraulic fracturing are required to optimize the production of hydrocarbons. There are numerous concerns associated with the utilization of conventional water-based polymeric solutions for fracturing shales. However, the gas utilization has been found as an exceptional stimulation approach providing various benefits. CO2 foam, an energized fracturing fluid, has been used to overcome the limitation of conventional fracturing fluid. CO2 foam is able to enhance hydrocarbon production by addressing the critical issues associated with the conventional technique. The rheological property of CO2 foam fracturing fluid is a key factor controlling the efficiency of overall processes. Different models describing the foam flow behavior have been produced and numerous investigations have been conducted to explain the rheological behavior of foam for fracturing purpose. Various process variables, such as foam quality, temperature, pressure, shear rate, surfactant concentration, and salinity strongly affect foam rheology behavior giving an impact on designing foam fracturing fluid at required fracturing conditions. In-depth analysis and information gathering are substantially required to ascertain
