A New Method of Plugging the Fracture to Enhance Oil Production for Fractured Oil Reservoir using Gel Particles and the HPAM/Cr3+ System

Abstract

Due to the strong heterogeneity between the fracture and the matrix in fractured oil reservoirs, injected water is mainly moved forward along the fracture, which results in poor water flooding. Therefore, it is necessary to reduce the water cut and increase oil production by using the conformance control technology. So far, gel particles and partially hydrolyzed polyacrylamide (HPAM)/Cr3+ gel are the most common applications due to their better suitability and low price. However, either of the two alone can only reduce the conductivity of the fracture to a certain extent, which leads to a poor effect. Therefore, to efficiently plug the fracture to enhance oil recovery, a combination of gel particles and the HPAM/Cr3+ system is used by laboratory tests according to their respective advantages. The first step is that the gel particles can compactly and uniformly cover the entire fracture and then the fracture channel is transformed into the gel particles media. This process can enhance the oil recovery to 18.5%. The second step is that a suitable HPAM/Cr3+ system based on the permeability of the gel particles media is injected in the fractured core. Thus, the fracture can be completely plugged and the oil in the matrix of the fractured core can be displaced by water flooding. This process can enhance oil recovery to 10.5%. During the whole process, the oil recovery is increased to 29% by this method. The results show that this principle can provide a new method for the sustainable and efficient development of fractured oil reservoirs.

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for In-Depth Water Control in Mature Oilfields

“…GT = 3.58 + 18.6C NaCit (6) where C NaCit is the concentration of NaCit in mg/L. To further discuss the retarding capacity of NaCit on NPAM/PEI gel system, the samples in the presence of NaCit, NaCl, and NH 4 Cl were compared with the same mass fraction in Figure 6.…”

“…The hydrolyzed polyacrylamide contains many amide groups (-CONH 2 ) and carboxyl groups (-COO − ) in its molecular chain. It could crosslink with different types of crosslinkers, such as Cr 3+ [ 6 , 7 ], Al 3+ [ 8 ], Zr 4+ [ 9 ], phenolic resin [ 10 , 11 ], etc. However, multivalent metal ions and phenolic resin are toxic.…”

Regulating Gelation Time and Kinetics Analysis Based on the ARGET ATRP Mechanism

“…More and more oilfields are entering into the period of high water‐cut, especially in China . Early water breakthrough in oil well and water well increases water cut and decreases oil production, resulting in increased operating costs related to artificial lifting, oil and water separation, and treatment of produced water . This may reach a level where production from a certain well is no longer feasible.…”

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for Indepth Water Control in Mature Oilfields

“…The polyacrylamide contains a large number of amide groups (-CONH2) and carboxyl groups (-COO -) in its molecular chain after hydrolysis. It could crosslink with different types of crosslinkers, such as Cr 3+ [6,7], Al 3+ [8], Zr 4+ [9] or phenolic resin [10][11] et al. However, multivalent metal ions and phenolic resin are toxic.…”