Rules of thumb, intuitive planning and physical insight

Author(s):  
Jeffrey H Williams
Author(s):  
Y. Anggoro

The Belida field is an offshore field located in Block B of Indonesia’s South Natuna Sea. This field was discovered in 1989. Both oil and gas bearing reservoirs are present in the Belida field in the Miocene Arang, Udang and Intra Barat Formations. Within the middle Arang Formation, there are three gas pay zones informally referred to as Beta, Gamma and Delta. These sand zones are thin pay zones which need to be carefully planned and economically exploited. Due to the nature of the reservoir, sand production is a challenge and requires downhole sand control. A key challenge for sand control equipment in this application is erosion resistance without inhibiting productivity as high gas rates and associated high flow velocity is expected from the zones, which is known to have caused sand control failure. To help achieve a cost-effective and easily planned deployment solution to produce hydrocarbons, a rigless deployment is the preferred method to deploy downhole sand control. PSD analysis from the reservoir zone suggested from ‘Industry Rules of Thumb’ a conventional gravel pack deployment as a means of downhole sand control. However, based on review of newer globally proven sand control technologies since adoption of these ‘Industry Rules of Thumb’, a cost-effective solution could be considered and implemented utilizing Ceramic Sand Screen technology. This paper will discuss the successful application at Block B, Natuna Sea using Ceramic Sand Screens as a rigless intervention solution addressing the erosion / hot spotting challenges in these high rate production zones. The erosion resistance of the Ceramic Sand Screen design allows a deployment methodology directly adjacent to the perforated interval to resist against premature loss of sand control. The robust ceramic screen design gave the flexibility required to develop a cost-effective lower completion deployment methodology both from a challenging make up in the well due to a restrictive lubricator length to the tractor conveyancing in the well to land out at the desired set depth covering the producing zone. The paper will overview the success of multi-service and product supply co-operation adopting technology enablers to challenge ‘Industry Rules of Thumb’ replaced by rigless reasoning as a standard well intervention downhole sand control solution where Medco E&P Natuna Ltd. (Medco E&P) faces sand control challenges in their high deviation, sidetracked well stock. The paper draws final attention to the hydrocarbon performance gain resulting due to the ability for choke free production to allow drawing down the well at higher rates than initially expected from this zone.


Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 215
Author(s):  
Paul McGinn ◽  
Daniel Pearce ◽  
Yannis Hardalupas ◽  
Alex Taylor ◽  
Konstantina Vogiatzaki

This paper provides new physical insight into the coupling between flow dynamics and cavitation bubble cloud behaviour at conditions relevant to both cavitation inception and the more complex phenomenon of flow “choking” using a multiphase compressible framework. Understanding the cavitation bubble cloud process and the parameters that determine its break-off frequency is important for control of phenomena such as structure vibration and erosion. Initially, the role of the pressure waves in the flow development is investigated. We highlight the differences between “physical” and “artificial” numerical waves by comparing cases with different boundary and differencing schemes. We analyse in detail the prediction of the coupling of flow and cavitation dynamics in a micro-channel 20 m high containing Diesel at pressure differences 7 MPa and 8.5 MPa, corresponding to cavitation inception and "choking" conditions respectively. The results have a very good agreement with experimental data and demonstrate that pressure wave dynamics, rather than the “re-entrant jet dynamics” suggested by previous studies, determine the characteristics of the bubble cloud dynamics under “choking” conditions.


Author(s):  
Carlos Alós-Ferrer ◽  
Johannes Buckenmaier ◽  
Georg Kirchsteiger

AbstractWhen alternative market institutions are available, traders have to decide both where and how much to trade. We conducted an experiment where traders decided first whether to trade in an (efficient) double-auction institution or in a posted-offers one (favoring sellers), and second how much to trade. When sellers face decreasing returns to scale (increasing production costs), fast coordination on the double-auction occurs, with the posted-offers institution becoming inactive. In contrast, under constant returns to scale, both institutions remain active and coordination is slower. The reason is that sellers trade off higher efficiency in a market with dwindling profits for biased-up profits in a market with vanishing customers. Hence, efficiency alone might not be sufficient to guarantee coordination on a single market institution if the surplus distribution is asymmetric. Trading behavior approaches equilibrium predictions (market clearing) within each institution, but switching behavior across institutions is explained by simple rules of thumb, with buyers chasing low prices and sellers considering both prices and trader ratios.


2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Peng Zhao ◽  
Yihang Zhang ◽  
Rongrong Sun ◽  
Wen-Sheng Zhao ◽  
Yue Hu ◽  
...  

A compact frequency selective surface (FSS) for 5G applications has been designed based on 2.5-dimensional Jerusalem cross. The proposed element consists of two main parts: the successive segments of the metal traces placed alternately on the two surfaces of the substrate and the vertical vias connecting traces. Compared with previous published two-dimensional miniaturized elements, the transmission curves indicate a significant size reduction (1/26 wavelengths at the resonant frequency) and exhibit good angular and polarization stabilities. Furthermore, a general equivalent circuit model is established to provide direct physical insight into the operating principle of this FSS. A prototype of the proposed FSS has been fabricated and measured, and the results validate this design.


2021 ◽  
Vol 198 ◽  
pp. 109655
Author(s):  
Fabio C. Bagliano ◽  
Carolina Fugazza ◽  
Giovanna Nicodano

2003 ◽  
Vol 25 (1) ◽  
pp. 1-36 ◽  
Author(s):  
Karsten Rodenacker ◽  
Ewert Bengtsson

Feature extraction is a crucial step in most cytometry studies. In this paper a systematic approach to feature extraction is presented. The feature sets that have been developed and used for quantitative cytology at the Laboratory for Biomedical Image Analysis of the GSF as well as at the Center for Image Analysis in Uppsala over the last 25 years are described and illustrated. The feature sets described are divided into morphometric, densitometric, textural and structural features. The latter group is used to describe the eu‐ and hetero‐chromatin in a way complementing the textural methods. The main goal of the paper is to bring attention to the need of a common and well defined description of features used in cyto‐ and histometrical studies. The application of the sets of features is shown in an overview of projects from different fields. Finally some rules of thumb for the design of studies in this field are proposed. Colour figures can be viewed onhttp://www.esacp.org/acp/2003/25‐1/rodenacker.htm.


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