Evaluate Wettability and Production Potential of Tight Reservoirs Through Spontaneous Imbibition Using Time-Lapse NMR and Other Measurements

Several studies have shown that rock-fluid interactions in tight rocks are influenced by the natural wettability behavior of the various pore systems. Studying the water/oil displacement on a smaller scale using core plug imbibition and monitoring with NMR is very insightful in evaluating wettability and distinguishing pore modes and rock types based on their fluid affinity. Extending learnings from plug-scale imbibition process to reservoir production behavior requires understanding of the underlying compositional and/or textural parameters controlling the wettability. This paper presents a systematic study of spontaneous imbibition of oil and water in core plugs procured from several tight and organic-rich reservoirs with varying mineral composition and organic content. The experiment comprised three identical core plugs from the same depth undergoing multiple fluid imbibition cycles with one plug starting in produced brine, the second one in produced crude and the last one in decane. Sample weights were continuously monitored and when stable, a sample which was in brine was moved to crude and the one in crude was moved to brine. This process was repeated for four cycles so that samples that started in brine finally ended up in crude and those that started in crude ended up in brine. The saturation changes and rock-fluid interaction in different fluid types were monitored using a 12 MHz NMR spectrometer. The 12 MHz NMR allowed very accurate partitioning of the oil-filled and water-filled porosity in these tight rocks, which was essential for the wettability analysis. The rate and extent of saturation changes varied significantly from sample to sample. The comparison between the companion plugs imbibing either higher amounts of oil or water revealed the fluid affinity of each sample. We computed the ratio of the net incremental fluid fraction to the total porosity to represent the dominant pore wetting system for rock samples at a given depth. We measured organic content and mineralogy of the samples and analyzed the matrix effect on wettability. We analyzed the post-imbibition NMR relaxation times (T1,T2) of individual fluid types and integrated with matrix properties to evaluate oil and water mobilities. We found predicted fluid mobilities to be consistent with the observed production from wells drilled in the different reservoirs and rock types. We observed most samples attain 100% fluid saturation within two to four cycles and almost all the samples at a given depth took up very similar water volumes irrespective of whether the companion plugs started in brine or crude. The process highlighted that water-wet pores governed the final water saturation, which was strongly correlated with total clay. The amount of organic content and carbonate minerals influenced the oil uptake and its relative mobility. For samples that started in decane, decane was imbibed faster and caused samples to attain higher oil saturation than samples that started in crude.

Kinetics of Oil Absorption and Moisture Loss during Deep-Frying of Pork Skin with Different Thickness

We have investigated different properties (thickness, moisture loss, oil uptake, breaking force, color, puffing ratio during 0.5–5 min frying, microstructure, and sensory evaluation) of raw pork skins with varying thickness (2, 3, and 4 mm) after drying, intended as deep-fried snacks. We have found that the oil content, breaking force, and puffing ratio of fried pork skin with different raw skin thickness have no significant difference under similar water content (1.68–1.98 g/100 g wet weight basis, wb) after 3–5 min of deep-frying at 180 °C. Additionally, sensory score results have shown that fried pork skins with 4 mm raw skin thickness had lower flavor, texture, and overall acceptability than those with 2 mm and 3 mm raw skin thickness. Scanning electron micrographs (SEM) have revealed less holes and irregular and crack microstructure in fried pork skins with 4 mm raw skin thickness than in other groups. Different thickness of raw pork skins resulted in different effects in microstructure and influenced water evaporation and oil uptake of fried pork skin. Finally, we have proposed the kinetic equations of water loss and oil uptake of fried pork skins. Fried pork skin from raw skin thicker than 4 mm need frying at temperature higher than 180 °C to improve their puffing ratio and sensory acceptability.

Efficient Eco-Friendly Nano-Extracted Gelatin as Biodegradable Packaging Material

Extracted gelatin from the waste of fresh and grilled chicken skin was used to prepare films as a biodegradable packaging material from solutions of various gelatin concentrations using a casting approach. The thermal behavior of extracted gelatins was investigated by differential scanning calorimetric. The particle size and zeta potential of dispersed nanoparticles of gelatins were measured by dynamic light scattering. The surface area of lyophilized gelatin nanoparticles was calculated from the adsorption of N2 gas. Mechanical properties, water vapor permeability (WVP), and oil uptake (OU) of all manufactured films were studied. Tensile strength values significantly increased for films manufactured from both gelatin sources when the concentration increased from 4 % to 6 % up to 5.1 MPa. The elongation of waste skin gelatin-based films was higher than waste grilled skin gelatin (WG)-based films using 4 % and 8 % concentrations up to 57 %. Films manufactured from WG had significantly lower WVP than waste skin gelatin (WS) analogous at a 4 % gelatin concentration. The WVP of films manufactured from gelatin significantly increased as gelatin concentration increased where OU showed higher oil resistance for films manufactured from WS up to 91 % using 4 % gelatin concentration. The morphological structure of the gelatin film was investigated with scanning electron microscopy (SEM). A homogenized and smooth film surface was observed. The percentage of heavy metal was examined by inductively coupled plasma (ICP). The results of this study showed that the films manufactured using higher concentrations of gelatin possessed promising mechanical properties, good barrier properties, and high safety as a recommended biopolymer packaging material for food contact and pharmaceutical applications.

Application of Milk Proteins Co-Precipitates Prepared Using Different Types of Minerals as Coating Materials to Reduce Oil Uptake of Fried Potato Strips

The edible coatings are a suitable method to decrease oil uptake in fried foods. In this study, the effects of milk protein co-precipitates aggregated using different types of minerals (CaCl2: 17 mM, FeCl3: 18 mM, ZnCl2: 18 mM, and MgCl2: 20 mM) and affected on the properties of fried potato strips were evaluated. Edible coating solutions were performed at two concentrations (%2.5 w/v) and (%5 w/v. According to the results, coated potato slices with edible coating solutions based on milk proteins co-precipitated by MgCl2 (%5) recorded higher hardness value among all the salts before frying process. Generally after frying process, coated French fries with edible coating solutions were the hardest comparable with uncoated (control) French fries, at the %2.5 w/v concentration the higher hardness value was recorded by coated French fries with CaCl2 milk protein co-precipitates and at the %5 w/v concentration the higher hardness value was recorded by coated French fries with milk protein co-precipitates ZnCl2. The experimental results showed that the coating solutions based on milk proteins co-precipitated had a positive and great effect on reducing oil uptake. In conclusion, The edible coating solutions based on milk proteins co-precipitated prepared by ZnCl2, MgCl2 at concentration %5 (w/v) reduced oil adsorption more than other coating solutions and in the same time increased the moisture content of final products sequentially compared with uncoated (control) samples. According to the sensory test, coated French fries with milk proteins co-precipitated by MgCl2 had the higher sensory evaluation degrees in appearance, color, taste and overall acceptability, while coated French fries with milk proteins co-precipitated by ZnCl2 got the highest sensory evaluation degrees for texture.

Quantification of Oil Fractions of Deep-Fried Wheat Dough and Batter Enriched with Oat and Wheat Bran

This study investigated oil distribution in two types of deep-fried dough products with two moisture levels (65 and 100 wt. %), two bran types (oat and wheat bran), and five bran concentrations (5–20%). The total oil content of fried products was categorised as surface oil (SO), penetrated surface oil (PSO), and structural oil (STO) using a spectrophotometric method. Moisture loss reduced ( p < 0.05 ) from 23.35% in the control to 15.19% fried batter (FB) and to 20% oat bran (OB), while a reverse trend was observed in the fried dough. Reduction of total oil from 0.43 g/g in the control to 0.38 g/g at 20% OB and 8% wheat bran (WB) was observed. At 15% OB and 20% WB, total fat reduced from 0.41 g/g in the control to 0.26 g/g of fried dough (FD). The trend STO < SO < PSO was observed in FD, while FB followed a SO < STO < PSO trend. This investigation indicated that oil uptake reduction in fried dough products is achievable through ingredient modifications. The method of oil distribution measurement used herein can be applied to other thick deep-fried food systems in the assessment of product quality.