Weight-Sharing Regularization

Weight-sharing is ubiquitous in deep learning. Motivated by this, we propose a "weight-sharing regularization" penalty on the weights $w \in \mathbb{R}^d$ of a neural network, defined as $\mathcal{R}(w) = \frac{1}{d - 1}\sum_{i > j}^d |w_i - w_j|$. We study the proximal mapping of $\mathcal{R}$ and provide an intuitive interpretation of it in terms of a physical system of interacting particles. We also parallelize existing algorithms for $\operatorname{prox}_\mathcal{R}$ (to run on GPU) and find that one of them is fast in practice but slow ($O(d)$) for worst-case inputs. Using the physical interpretation, we design a novel parallel algorithm which runs in $O(\log^3 d)$ when sufficient processors are available, thus guaranteeing fast training. Our experiments reveal that weight-sharing regularization enables fully connected networks to learn convolution-like filters even when pixels have been shuffled while convolutional neural networks fail in this setting. Our code is available on github.Comment: Our code is available at https://github.com/motahareh-sohrabi/weight-sharing-regularizatio

Dissolution of Rock During Smart Water Injection in Heavy Oil Carbonate Reservoirs by Natural Generation of Acidic Water

Smart waters have been studied for enhanced oil recovery in carbonate reservoirs, gaining significant attention from research groups and oil industry companies. However, there is a general consensus that the complexity of the fluids/rock system governs their effects, much fundamental knowledge is lacking, and many questions and uncertainties remain. For instance, the existence of rock dissolution in carbonate rocks, as a mechanism for oil production, has previously been documented. This work specifically focused on the interaction oil–brine–rock and its effect on rock dissolution. Carbonate rocks (limestones and dolomites), brines, and heavy crude oils were individually analyzed and then systematically mixed with each other to gain a comprehensive understanding of their interactions. Five heavy crude oils with different properties were tested under similar reservoir conditions (≈92 °C). Results revealed the generation of acidic water derived from the interaction between injected fluids and crude oils. Not all crude oils could produce acidic water, which is the cause of rock dissolution. This research suggests that the chemical interaction between crude oil and injected water may be one of the main reasons for the increased efficiency in response to the use of the smart waters for the improvement of oil production. Basic analyses that are presented here essentially provide an insight into the impact of the chemical interaction between crude oil and injection water with the rock. Finally, coreflood experiments were performed using a dolomitic core in order to monitor and verify the presence of dissolution during the flow of fluids. A basic crude oil was selected for this purpose. Effluent analysis, pH measurements, and permeability evaluations corroborated the influence caused by smart water injection as acidic water in contact with the rock. The findings of these experiments prove that is possible to predict and control the occurrence of the dissolution, observing interactions of crude oil and injection water.The authors would like to acknowledge financial support for this work provided by the National Council of Science and Technology and the Ministry of Energy of Mexico (Conacyt-Sener-Hicrocarburos)

Carbonated water injection (CWI) - a productive way of using CO2 for oil recovery and CO2 storage

AbstractThe main advantage of CO2 is that at most reservoir conditions it is a supercritical fluid which is likely to develop miscibility with the oil. In reservoirs that miscibility cannot be achieved, CO2 injection can lead to additional oil recovery by mixing with the oil and favourably modifying the flow properties of the oil. Displacement and recovery of oil by CO2 injection has been studied and applied in the field extensively in the past three decades. Concerns over the environmental impact of CO2 have led to a resurgence of interest in CO2 injection in oil reservoirs. The injection of CO2 can enhance oil recovery from these reservoirs and at the same time help mitigating the problem of increased CO2 concentrations in the atmosphere by storing large quantities of CO2 for a long period of time.CO2 injection projects so far have been mainly limited geographically to oil fields located in areas where large quantities of CO2 have been available mainly from natural resources. Various CO2 injection strategies e.g. cyclic injection, continuous CO2 flood, alternating (WAG) or simultaneous injection of CO2 and water have been applied in these fields. With the new global interest in CO2 injection, many other reservoir settings and scenarios are being considered for CO2 injection in oil reservoirs. This may require injection strategies other than those conventionally used for CO2 injection especially for offshore reservoirs or in cases where the supply of CO2 can be variable or limited.An alternative CO2 injection strategy is carbonated (CO2-enriched) water injection. In carbonated water, CO2 exists as a dissolved phase as opposed to a free phase eliminating the problems of gravity segregation and poor sweep efficiency, which are characteristics of a typical CO2 injection project. In fact, both viscosity and density of water increase as a result of the dissolution of CO2 in water. In terms of CO2 storage, through carbonated water injection, large volumes of CO2 can be injected into the reservoir without the risk of leakage of CO2 through caprock.Using the results of a series of high-pressure flow visualisation experiments, we reveal the underlying physical processes taking place during CWI. The results show that CWI, compared to conventional water injection, improves oil recovery in both secondary (pre-waterflood) and tertiary (post-waterflood) injection modes. Several key mechanisms taking place at the pore level during CWI leading to additional recovery are presented and discussed. Both conventional (light) oil and viscous oil was used in the experiments

Levofloxacin loaded poly (ethylene oxide)-chitosan/quercetin loaded poly (D,L-lactide-co-glycolide) core-shell electrospun nanofibers for burn wound healing

This study developed a new burn wound dressing based on core-shell nanofibers that co-deliver antibiotic and antioxidant drugs. For this purpose, poly(ethylene oxide) (PEO)-chitosan (CS)/poly(D,L-lactide-co-glycolide) (PLGA) core-shell nanofibers were fabricated through co-axial electrospinning technique. Antibiotic levofloxacin (LEV) and antioxidant quercetin (QS) were incorporated into the core and shell parts of PEO-CS/PLGA nanofibers, respectively. The drugs could bond to the polymer chains through hydrogen bonding, leading to their steady release for 168 h. An in vitro drug release study showed a burst effect followed by sustained release of LEV and QS from the nanofibers due to the Fickian diffusion. The NIH 3T3 fibroblast cell viability of the drug loaded core-shell nanofibers was comparable to that in the control (tissue culture polystyrene) implying biocompatibility of the nanofibers and their cell supportive role. However, there was no significant difference in cell viability between the drug loaded and drug free core-shell nanofibers. According to in vivo experiments, PEO-CS-LEV/PLGA-QS core-shell nanofibers could accelerate the healing process of a burn wound compared to a sterile gauze. Thanks to the synergistic therapeutic effect of LEV and QS, a significantly higher wound closure rate was recorded for the drug loaded core-shell nanofibrous dressing than the drug free nanofibers and control. Conclusively, PEO-CS-LEV/PLGA-QS core-shell nanofibers were shown to be a promising wound healing material that could drive the healing cascade through local co-delivery of LEV and QS to burn wounds