Modified Starches Used as Additives in Enhanced Oil Recovery (EOR)

OLIVIA V. LÓPEZ; LUCIANA A. CASTILLO; MARIO D. NINAGO; ANDRÉS E. CIOLINO; MARCELO A. VILLAR

Industrial Applications of Renewable Biomass Products

Springer International Publishing AG

Año: 2017; p. 227 - 248

Nowadays, oil recovery involves mainly three phases: primary, secondary and tertiary. In primary phase, natural pressure of the reservoir is employed to push crude oil to the surface, allowing a yield up to 10 %. In the second one, pressurized gas and water are injected to recover part of the oil remnant (~ 30 %). However, heterogeneous nature of the reservoirs hinders the complete oil phase extraction. Thus, a tertiary phase emerged called Enhanced Oil Recovery (EOR). This is considered a multidisciplinary area which involves not only scientific but also technological concepts in order to develop new methodologies to enhance the crude oil extraction and to extend the production life of oilfields. EOR implementation arises as a supplementary technology to conventional ones, optimizing the not-easily recoverable oil phase. Within this context, the estimation of oil remnant in reservoirs approaches to 7.0 x 1012 barrels, after primary and secondary recoveries are concluded. One of the strategies proposed for EOR implies the use of sophisticated displacing fluids which are pumped into the reservoir forcing the oil to flow towards the production wells. For this purpose, several ionic polymers are added to flood water to enhance oil extraction mainly through two different mechanisms. On one hand, these displacing fluids force the oil out of the pores and the rocks surfaces. On the other hand, the use of these sophisticated fluids allows reducing water permeability through rocks surfaces. Even though several water-soluble polymers are currently being used, starch is considered as a good alternative to employ in tertiary recovery due to its wide availability, stability and inherent environmental friendliness. Thus, the state of the art related to the use of different starch derivatives in EOR is included in this chapter. Besides, diverse methodologies used to synthesize modified starches are presented, analyzing the optimal conditions of each reaction. Particularly, the synthesis of cationic and crosslinked starches are reported since these modified starches are the most used in EOR. Modification degree as well as physicochemical properties of the derivatives are included and well discussed in this chapter. Rheological and flow properties of displacing fluids are also discussed as a function of starch concentration.