Field Data and Laboratory Study to Investigate Water and Gas Injectivity and Cyclic Hysteresis in Miscible WAG Injection in Carbonate Reservoir

The objective of this paper is to investigate the water and gas injectivity in water alternating gas (WAG) projects using laboratory and field scale data. It has been reported in the literature that both gas and water mobility has been significantly reduced in three-phase flow compared to two-phase flow. This behaviour has been attributed to a cycle dependent hysteresis effect which reduced both gas and water mobility in the different injection cycles. To address the gas and water injectivity and the cycle dependent hysteresis concept, the results of a detailed experimental program in addition to field injectivity data will be presented. The experimental program included three-phase experiments performed under reservoir conditions using live crude oil and carbonate reservoir core material. The core wettability was restored by ageing the core in crude oil for several weeks under reservoir conditions and CO2 was used as miscible injectant. The field injectivity data is obtained from two CO2 WAG pilots in a carbonate reservoir. The main conclusions of the study are: 1- Gas injectivity in the presence of mobile water is much lower than that in the absence of water, 2- Water injectivity in experiments starting with water cycle is better than that in experiments starting with gas cycle when compared at the same water saturation, 3- Cyclic hysteresis in gas relative permeability was observed when comparing the first and second gas cycle, however, no further hysteresis was observed in the subsequent gas injection cycles, 4- Cyclic hysteresis in water relative permeability was not observed, the injectivity was either the same or higher in the subsequent cycles. 5- The gas injectivity at similar gas saturation for experiments starting with gas is better than that for experiments starting with water, 6- Gas and water injectivity field data from ongoing CO2 WAG projects in carbonate reservoirs showed no cyclic hysteresis, the injectivity either the same or improved in the subsequent cycles, 7- The CO2 injectivity was lower than expected, in the same order as water injectivity, which could be due to injecting CO2 in high water saturation zone and 8) The low CO2 injectivity could have a positive impact on sweep efficiency and potential improvement of oil recovery. This paper presents the results of a well-designed experimental program and field data from two CO2 WAG pilots to systematically investigate water and gas injectivity in miscible WAG projects in carbonate reservoirs. The paper provides a rich and rarely available set of experimental and field data that can help improve and optimize gas and WAG injection projects in carbonate reservoirs. Detailed analysis of the field gas and water injectivity data will be presented and discussed in-light of the laboratory experimental data.

In situ investigation of water on MXene interfaces

A continuum of water populations can exist in nanoscale layered materials, which impacts transport phenomena relevant for separation, adsorption, and charge storage processes. Quantification and direct interrogation of water structure and organization are important in order to design materials with molecular-level control for emerging energy and water applications. Through combining molecular simulations with ambient-pressure X-ray photoelectron spectroscopy, X-ray diffraction, and diffuse reflectance infrared Fourier transform spectroscopy, we directly probe hydration mechanisms at confined and nonconfined regions in nanolayered transition-metal carbide materials. Hydrophobic (K+) cations decrease water mobility within the confined interlayer and accelerate water removal at nonconfined surfaces. Hydrophilic cations (Li+) increase water mobility within the confined interlayer and decrease water-removal rates at nonconfined surfaces. Solutes, rather than the surface terminating groups, are shown to be more impactful on the kinetics of water adsorption and desorption. Calculations from grand canonical molecular dynamics demonstrate that hydrophilic cations (Li+) actively aid in water adsorption at MXene interfaces. In contrast, hydrophobic cations (K+) weakly interact with water, leading to higher degrees of water ordering (orientation) and faster removal at elevated temperatures.

3D Printing of Shiitake Mushroom Incorporated with Gums as Dysphagia Diet

With the speeding tendency of aging society, the population experienced dysphagia is increasing quickly. Desirable dysphagic diets should be safe, visually appealing and nutritious. 3D printing allows for creation of personalized nutritious foods with regular-like appearance. Shiitake mushroom, rich in protein and bioactive compounds, is suitable for elderly, but its hard texture was not friendly to the elderly with dysphagia. This study investigated the feasibility of production of dysphagic product using shiitake mushroom by 3D printing with various gums addition, including arabic gum (AG), xanthan gum (XG) and k-carrageenan gum (KG) at concentrations of 0.3%, 0.6% and 0.9% (w/w). Data suggested that XG and KG incorporation significantly increased inks’ mechanical strength by decreasing water mobility and promoting the formation of hydrogen bond, enabling 3D printed objects with great self-supporting capacity. The XG containing and KG-0.3% samples were categorized into level 5—minced and moist dysphagia diet within international dysphagia diet standardization initiative (IDDSI) framework. AG addition decreased mechanical strength and viscosity, hardness and self-supporting capacity of 3D printed constructions. AG-0.3% and AG-0.6% samples could not be classified as dysphagia diets based on IDDSI tests. This study provides useful information for dysphagia diet development with appealing appearance by 3D printing.

An Improved Study of Emulsion Flooding for Conformance Control in a Heterogeneous 2D Model with Lean Zones

Summary Use of oil-in-water (O/W) emulsion has shown its potential for conformance control in heterogeneous porous media, yet it is essential to understand how to improve the conformance control performance in the heterogeneous 2D model with lean zones before it is applied in the fields. In this paper, an O/W emulsion-based conformance control method is improved through newly designed flow tests and optimized modeling study. A heterogeneous 2D model was designed with a high water mobility zone (HWMZ) and a low water mobility zone (LWMZ) separated by a horizontal injection well to mimic real oil sands with lean zones (top- or bottomwater) and with application of horizontal wells. Optimal conformance control strategies were proposed and examined in the 2D model by injecting correspondingly designed O/W emulsions. In an improvement of our previously proposed emulsion flow model (Ding et al. 2020c), we introduce the real phenomena of permeability reduction (PR) coefficients in this paper to describe the three ambiguous coefficients: flow distribution coefficient (γ), plugging coefficient (α), and retention rate coefficient (a). This newly developed model can incorporate with characteristics of the emulsion and the heterogeneous porous media through the introduction of the experimentally derived PR coefficient. It is well established in COMSOL Multiphysics® (COMSOL AB 2005), and the modeling results show good agreement with the experimentally monitored results in the three types of flow tests. This work bridges experimental and mathematical studies on emulsion flow in 2D models associated with lean zones and is able to provide a guide on optimal emulsion design and injection strategy for optimal conformance control performances.