Study on the optimization of the performance of preformed particle gel (PPG) on the isolation of high permeable zone

Summary Preformed-particle gels (PPGs) have been applied for reducing excessive water production caused by fractures in reservoirs. A portion of the fractures existing in reservoirs is composed of a void part and a fracture tip. The PPG placement behavior and plugging performance could be mainly affected by the fracture tips. A fracture with a tip, called a “partially open fracture” in this paper, was designed to investigate the placement and water-plugging performance of PPG. Cylindrical sandstone cores were used to manufacture partially open fractures. Pressure data of PPG injection, post-gel water breakthrough, and stable injection were analyzed to investigate the PPG propagation and plugging performance with respect to water. Experiments with different PPG placing pressures were conducted to explore the effects of pressure on PPG water-plugging performance and dehydration. In the fractures with tips, the PPG injection pressure increased rapidly, and could reach any designed pressure with continued injection after gel filled the fracture. By setting the PPG placing pressure at 500, 1,000, and 2,000 psi, the blocking efficiency to water showed a growth with the increase of placing pressure. The reswelling experiments show that PPG samples dehydrated when exposed to a high pressure difference between fracture and porous rock. Moreover, the placed PPG dehydrated relatively evenly along the fracture. Some gel particles were found whitening and reducing the capability of reswelling at the placing pressure of 2,000 psi. Scanning-electron-microscope (SEM) images indicated that the distinct 3D network of the PPG was compressed or damaged in the whitish sample. In addition, a discussion about PPG dehydration and fracture-tip extension is provided. In general, this study experimentally characterized PPG placement and plugging performance with respect to water in the fracture with tips. The PPG dehydration and fracture extension in PPG treatment, which have not drawn much attention in the literature, are investigated in this paper.

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A Novel Re-Crosslinkable Preformed Particle Gel for Conformance Control in Extreme Heterogeneous Reservoirs

10.2118/191697-ms ◽

2018 ◽

Cited By ~ 1

Author(s):

Jingyang Pu ◽

Baojun Bai ◽

Ali Alhuraishawy ◽

Thomas Schuman ◽

Yashu Chen ◽

...

Keyword(s):

Conformance Control ◽

Heterogeneous Reservoirs ◽

Preformed Particle Gel

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An Investigation of CO2-Responsive Preformed Particle Gel for Conformance Control of CO2 Flooding in Reservoirs With Fractures or Fracture-Like Channels

SPE Journal ◽

10.2118/197046-pa ◽

2019 ◽

Vol 24 (05) ◽

pp. 2398-2408 ◽

Cited By ~ 3

Author(s):

Ze Wang ◽

Baojun Bai ◽

Yifu Long ◽

Lizhu Wang

Keyword(s):

High Pressure ◽

Resistance Factor ◽

Real Field ◽

Swelling Ratio ◽

Co2 Flooding ◽

Conformance Control ◽

Residual Resistance ◽

Preformed Particle Gel ◽

Plugging Performance ◽

Residual Resistance Factor

Summary Gel treatment is an important technique to solve early CO2 breakthrough and excess–CO2–production problems, caused by the low viscosity and low density of CO2, as well as the heterogeneity of reservoirs with fractures or fracture–like channels. However, there is no reported work on gel that increases its volume after reacting with CO2 (termed CO2–responsive gel) for the conformance control of CO2 flooding. In this paper, the intrinsic properties of a CO2–responsive preformed particle gel (CR–PPG) were evaluated in a water/supercritical–CO2 (scCO2) environment in high–pressure vessels. Continuous scCO2 injection and CR–PPG treatment were conducted in fractured sandstone cores, to probe their plugging performance to scCO2 flow in a high–permeability–contrast system. The volumetric swelling ratio (VSR) of the CR–PPG increased by approximately two times in the presence of scCO2, compared with a sample under similar conditions in the absence of scCO2. The CR–PPG swelling ratio decreased with increasing NaCl concentration. Under the same conditions, the temperature did not have an apparent effect on the swelling ratio after 31 days of swelling. In coreflooding experiments, the placed CR–PPG resisted a considerable pressure up to 617.0 psi before breakthrough. After a shut–in process, CO2–breakthrough pressure was detected at 437.2 psi. It is observed that the shut–in process improved the plugging performance of CR–PPG to CO2 as revealed by the increase in the residual resistance factor. Controlling the shut–in time was found to be effective in augmenting the increase in the residual resistance factor, by increasing the VSR of placed CR–PPG. Resistance of CR–PPG to some real field challenges, including a high pressure gradient and long–term exposure to CO2, was also reported for field–applicability concerns.

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