Does Miscibility Matter In Gas Injection?

Abstract

Over the years gas injection design has undergone an evolution in the types of laboratory tests used to design a gas injection project as well as the interpretation of the experimental testing. In the recent past, there has been much written in the area of immiscible and near-miscible gas flooding. Often, some of these applications appear to be very effective and somewhat less expensive than the so-called "miscible"floods. In this paper the authors discuss some of the considerations which are germane to gas injection and provide evidence that suggests that many of the previously accepted laboratory techniques were not really providing what they were intended to.It is important that one understands the significance of these considerations when designing a gas injection project.The authors indicate that specific testing can be made to gain insight into the most important features of a gas injection project which concerns the interaction between the level of interfacial tension and the mobility 'effects. By appropriately quantifying whether a reservoir is going to be . IFT or mobility-dominated, the operator can concentrate on designing a gas to optimize thefactor which is dominant. It is important to know what that dominantfactor is so that gas injection processes are the best that they can be. In answer to the question asked in the title of this paper, the authors suggest that most gas injection projects would involve a gas which exhibits properties in the so-called "near-miscible" range. Techniques for determining how miscible one needs to become provided in this paper. This paper is to be presented at

Evaluating Reservoir Production Strategies in Miscible and Immiscible Gas-Injection Projects

“…It is merely a well controlled experiment, with valuable results for simulating In spite of increasing knowledge and investigation [11][12] concerning the validity of slim-tube results, the slim-tube technique may not be as trustworthy as it was once thought to be. Dependence 13 of relative permeability data to the interfacial tension ratio suggests that the response of a slim tube is dominated by IFT effects, and there is very little influence of viscosity ratio in the slim tube.…”

Experimental Investigation of Various Methods of Tertiary Gas Injection

“…Although the popularity and benefits of the miscible mode of injection seem to outweigh the immiscible floods, there appear to be no consensus in the literature on the need for miscibility development [25][26][27] . Rogers and Grigg 9 state that interfacial tension is the most sensitive and easily modified parameter in the capillary number equation, and advocate miscibility development as a way of significantly decreasing the interfacial tension at relatively lower cost.…”

Does Miscibility of In Situ Generated Flue Gases With Light Crude Oils Contribute to Oil Recovery Under High Pressure Air Injection?

“…Air injection is especially applicable in low porosity and low permeability reservoirs where water injectivity is extremely low 3 . Apart from providing a better interfacial tension (IFT) response 4 , air injectivity is about ten times that of water in terms of reservoir volume 5 , making air injection more advantageous than water injection in deep, tight, high pressure reservoirs. A number of successful high pressure air injection projects in light oil reservoirs have been documented in the literature 5 -11 .…”