Acidizing Sandstone Reservoirs Using Different Acid Systems

AlCl₃ has been long used as a retarding agent for mud acid, its applications studied in the lab and tested in the field. The theory and mechanism of AlCl₃ retardation have been investigated in many projects involving mud acidizing and reservoir permeability enhancement. This dissertation advances this investigation by using solubility tests, coreflood tests, and ¹⁹F Nuclear Magnetic Resonance (NMR) to better understand the mechanism of AlCl₃ working as a retarding agent in mud acid. To enhance the acid performance and to minimize formation damage, this study provides a systematic investigation of the interactions between the Al-based retarded mud acid and clay minerals in sandstone reservoirs. Furthermore, for the first time, ¹⁹F NMR spectroscopy was used to follow the reactions of Al-based retarded mud acid with clay minerals. Solubility tests were performed to evaluate the retardation of the Al-based retarded mud acid when reacted with kaolinite, bentonite, and illite. Inductively Coupled Plasma (ICP) and ¹⁹F NMR were used to analyze the concentrations of key cations and components in the supernatant while the Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) techniques were used to identify the reaction products and detect any precipitation. This study shows that AlCl₃ can retard the reaction of HF with kaolinite, bentonite, or illite at 75 and 200°F in Al-based retarded mud acid. Even with 5 wt% AlC₃∙6H₂O added to the acid system, no AlF₃ precipitate was observed in any of the solubility tests. Coreflood tests showed significant permeability improvement in the Berea sandstone when Al-based retarded mud acid was used. The enhancement diminished when the temperature increased to 300°F. CT scan showed deeper penetration of Al-based retarded mud acid than mud acid at 75°F, and the penetration reduced when temperature increased to 200°F. Based on these results, new mechanisms were developed to better understand the reaction of Al-based retarded mud acid and clay minerals. Field tests were followed in this study. The optimal acidizing plan was found for the Katz field after a series of coreflood experiments. This study provides the guidelines for designing the acidizing jobs in the Katz field

Dynamic Properties of Saturated Coal Fly Ash

The great part of fly ash produced by thermal power plants is either sluiced or filled in disposal areas in China. The dynamic properties of fly ash are important for solving geotechnical problems relating to fly ash mass under dynamic loadings. The high temperature during combustion makes fly ash nonplastic but pozzolanic. The nonplasticity causes the dynamic properties of sluiced and just compacted fly ash to be similar to ones of silts. The pozzolanic action causes obvious aging effect for compacted fly ash, by which an aging time of 180 days may increase maximum shear modulus by 75% to 400% and cyclic strength by 100% to 500%. All of these results are reported and discussed in the paper in detail. Based on the results four correlative equations are presented which could be used to preliminarily evaluate the dynamic properties of fly ashes

Higher KK-Groups of Smooth Projective Curves Over Finite Fields

Let $X$ be a smooth projective curve over a finite field $\mathbb{F}$ with $q$ elements. For $m\geq 1,$ let $X_m$ be the curve $X$ over the finite field $\mathbb{F}_m$, the $m$-th extension of $\mathbb{F}.$ Let $K_n(m)$ be the $K$-group $K_n(X_m)$ of the smooth projective curve $X_m.$ In this paper, we study the structure of the groups $K_n(m).$ If $l$ is a prime, we establish an analogue of Iwasawa theorem in algebraic number theory for the orders of the $l$-primary part $K_n(l^m)\{l\}$ of $K_n(l^m)$. In particular, when $X$ is an elliptic curve $E$ defined over $\mathbb{F},$ our method determines the structure of $K_n(E).$ Our results can be applied to construct an efficient {\bf DL} system in elliptic cryptography.Comment: 20 page, 8 table

Energy-Efficient Task Offloading for Semantic-Aware Networks

The limited computation capacity of user equipments restricts the local implementation of computation-intense applications. Edge computing, especially the edge intelligence system enables local users to offload the computation tasks to the edge servers for reducing the computational energy consumption of user equipments and fast task execution. However, the limited bandwidth of upstream channels may increase the task transmission latency and affect the computation offloading performance. To overcome the challenge of the limited resource of wireless communications, we adopt a semantic-aware task offloading system, where the semantic information of tasks are extracted and offloaded to the edge servers. Furthermore, a proximal policy optimization based multi-agent reinforcement learning algorithm (MAPPO) is proposed to coordinate the resource of wireless communications and the computation, so that the resource management can be performed distributedly and the computational complexity of the online algorithm can be reduced.Comment: Have been accepted by IEEE ICC 202