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71.
72.
稠油出砂冷采颗粒离散元数学模型 总被引:3,自引:0,他引:3
疏松砂岩油藏渗流出砂问题的实质是砂岩地层微粒的剥蚀与运移,鉴于传统物理模拟方法的复杂性以及现有数值模拟方法在描述非连续介质方面的不足,建立了考虑流固耦合的颗粒离散元稠油出砂冷采数学模型,优选了Mohr-Coulomb屈服准则作为颗粒从母岩剥离的破坏准则,从微观角度定量描述出砂机理。数学模型模拟产砂速率、产油速率及井底压力结果与一维物理模型实验实测值均吻合较好,验证了模型的正确性和可靠性,在此基础上,定量描述了稠油出砂冷采的临界条件及蚓洞扩展规律。把所建立数学模型拓展到现场,计算结果表明,颗粒离散元数学模型能够正确描述稠油出砂冷采出砂规律,为研究稠油出砂冷采提供了一种新手段。图8参17 相似文献
73.
A fault-tolerant routing method that can tolerate solid faults using only two virtual channels is presented. The proposed
routing algorithm, called FT-Ecube, not only uses a fewer number of virtual channels but also tolerates f-chains in the meshes.
Furthermore, the proposed scheme misroutes messages both clockwise and counter clockwise directions to reduce channel contention
on f-rings. It is shown that the proposed algorithm is deadlock-free and livelock-free in meshes when it has nonoverlapping
multiple f-regions. Further, we conducted flit-level simulations to evaluate the performance of the proposed routing algorithm.
As our simulation results show, FT-Ecube tolerates multiple faulty blocks using only two virtual channels per physical channel,
and has good performance in terms of average latency.
This work is supported by the NSF grant MIP-9705738 相似文献
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滑溜水是页岩气、致密油非常规油气藏体积改造中应用最广泛的压裂液体系,旨在利用低黏滑溜水强的穿透性能激活天然裂缝提高裂缝复杂程度。基于深层裂缝性碳酸盐岩储层基质物性差、非均质性强,裂缝是主要储集空间和渗流通道的储层特征,提高改造体积是实现高产稳产的核心,需采用低黏流体大排量注入来提高天然裂缝激活几率,提出滑溜水、冻胶和转向酸复合的体积酸压技术。评价了新型聚合物类滑溜水性能,利用室内实验(大物模、酸液滤失)和数值模拟相结合的方法研究了滑溜水在体积酸压中的作用机理,研究表明:新型聚合物类滑溜水具有较好的减阻性能,能够降低施工管柱摩阻,实现大排量施工,助力改造效果提升;滑溜水大排量注入形成复杂裂缝,低黏酸液注入形成酸蚀蚓孔提高裂缝连通性,滑溜水与低黏酸交替注入,实现微细裂缝"水力+酸蚀"缝网构建。上述研究成果现场应用显著,AT3x井压后获日产油35 m3、日产气50.3×104 m3高产油气流,为国内超高温深层复杂储层高效改造提供新的技术指导。 相似文献
77.
Multicasting is an important issue for numerous applications in parallel and distributed computing. In multicasting, the same message is delivered from a source node to an arbitrary number of destination nodes. The star graph interconnection network has been recognized as an attractive alternative to the popular hypercube network. In this paper, we propose an efficient and deadlock-free tree-based multi-cast routing scheme for wormhole-routed star graph networks with hamiltonian path. In our proposed routing scheme, the router is with the input-buffer-based asynchronous replication mechanism that requires extra hardware cost. Meanwhile, the router simultaneously sends incoming flits on more than one outgoing channel. We perform simulation experiments with the network latency and the network traffic. Experimental results show that the proposed scheme reduces multicast latency more efficiently than other schemes. 相似文献
78.
We consider the problem of broadcasting a message in the n-cube, Qn, equipped with wormhole switching. The communication model assumed is one-port, and the broadcasting scheme is path-based whereby, during broadcasting along a path by a node, all the nodes on that path will receive the message. The wormhole path length is m where –m's concurrently (cube-based broadcast). The second method is based on the concept of Gray codes (GCs), and at every given step, it forms the Hamiltonian path of appropriate size as the broadcast path (GC-based broadcast). It is shown that the steps required in GC-based broadcast is fewer than or equal to those needed by cube-based broadcast. Furthermore, comparison of time complexity of GC-based broadcast to the lower bound reveals that this algorithm is near-optimal, and in fact optimal in many cases. This work improves on the best algorithm developed for path-based broadcast in one-port hypercube both in complexity and in simplicity. 相似文献
79.
Chao Lin 《The Journal of supercomputing》2004,30(1):37-64
This paper presents three efficient contention-free algorithms for broadcasting on heterogeneous networks of workstations (HNOW). In an HNOW, many different speed types of workstations can have distinct send and receive overhead. Previous research has shown that finding an optimal routing scheme in an HNOW is not easy [2,12], because properly arranging all workstations in the scheduling tree is difficult. Therefore, this investigation focuses mainly on enhancing the performance of an HNOW by properly arranging fastest nodes into the internal nodes of upper levels in the scheduling tree. Fastest node first is fundamental in designing an efficient algorithm. This paper presents three schemes called EBS, VBBS, and VBBSWF. All of these three schemes can be executed in O(n log(n)) time, where n is the number of workstations. They are all contention-free when broadcasting in an HNOW. Based on the simulation result, the proposed schemes outperform the broadcast with minimal steps [13] and the scheduling tree [22] generated by dynamic programing in an HNOW. 相似文献
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