On the Joint Calculation of Safety Stocks and Replenishment Order Quantities

1974 ◽  
Vol 25 (1) ◽  
pp. 173-177 ◽  
Author(s):  
D. Psoinos
Author(s):  
M. Hamzah

Classical Oil Country Tubular Goods (OCTG) procurement approach has been practiced in the indus-try with the typical process of setting a quantity level of tubulars ahead of the drilling project, includ-ing contingencies, and delivery to a storage location close to the drilling site. The total cost of owner-ship for a drilling campaign can be reduced in the range of 10-30% related to tubulars across the en-tire supply chain. In recent decades, the strategy of OCTG supply has seen an improvement resulting in significant cost savings by employing the integrated tubular supply chain management. Such method integrates the demand and supply planning of OCTG of several wells in a drilling project and synergize the infor-mation between the pipes manufacturer and drilling operators to optimize the deliveries, minimizing inventory levels and safety stocks. While the capital cost of carrying the inventory of OCTG can be reduced by avoiding the procurement of substantial volume upfront for the entire project, several hidden costs by carrying this inventory can also be minimized. These include storage costs, maintenance costs, and costs associated to stock obsolescence. Digital technologies also simplify the tasks related to the traceability of the tubulars since the release of the pipes from the manufacturing facility to the rig floor. Health, Safety, and Environmental (HSE) risks associated to pipe movements on the rig can be minimized. Pipe-by-pipe traceability provides pipes’ history and their properties on demand. Digitalization of the process has proven to simplify back end administrative tasks. The paper reviews the OCTG supply methods and lays out tangible improvement factors by employ-ing an alternative scheme as discussed in the paper. It also provides an insight on potential cost savings based on the observed and calculated experiences from several operations in the Asia Pacific region.


Author(s):  
Felix Herold ◽  
Daniel Hug ◽  
Christoph Thäle

AbstractPoisson processes in the space of $$(d-1)$$ ( d - 1 ) -dimensional totally geodesic subspaces (hyperplanes) in a d-dimensional hyperbolic space of constant curvature $$-1$$ - 1 are studied. The k-dimensional Hausdorff measure of their k-skeleton is considered. Explicit formulas for first- and second-order quantities restricted to bounded observation windows are obtained. The central limit problem for the k-dimensional Hausdorff measure of the k-skeleton is approached in two different set-ups: (i) for a fixed window and growing intensities, and (ii) for fixed intensity and growing spherical windows. While in case (i) the central limit theorem is valid for all $$d\ge 2$$ d ≥ 2 , it is shown that in case (ii) the central limit theorem holds for $$d\in \{2,3\}$$ d ∈ { 2 , 3 } and fails if $$d\ge 4$$ d ≥ 4 and $$k=d-1$$ k = d - 1 or if $$d\ge 7$$ d ≥ 7 and for general k. Also rates of convergence are studied and multivariate central limit theorems are obtained. Moreover, the situation in which the intensity and the spherical window are growing simultaneously is discussed. In the background are the Malliavin–Stein method for normal approximation and the combinatorial moment structure of Poisson U-statistics as well as tools from hyperbolic integral geometry.


2010 ◽  
Vol 49 (4) ◽  
pp. 1233-1233
Author(s):  
J.J. Kanet ◽  
M.F. Gorman ◽  
M. Stößlein

1995 ◽  
Vol 27 (2) ◽  
pp. 326-343 ◽  
Author(s):  
Viktor Beneš

Formulas for anisotropic stereology of fibre and surface processes are presented. They concern the relation between second-order quantities of the original process and its projections and sections. Various mathematical tools for handling these formulas are presented, including stochastic optimization. Finally applications in stereology are discussed, relating to intensity estimators using anisotropic sampling designs. Variances of these estimators are expressed and evaluated for processes with the Poisson property.


Author(s):  
Joa˜o Pessoa ◽  
Nuno Fonseca ◽  
C. Guedes Soares

The paper presents an investigation of the slowly varying second order drift forces on a floating body of simple geometry. The body is axis-symmetric about the vertical axis, like a vertical cylinder with a rounded bottom and a ratio of diameter to draft of 3.25. The hydrodynamic problem is solved with a second order boundary element method. The second order problem is due to interactions between pairs of incident harmonic waves with different frequencies, therefore the calculations are carried out for several difference frequencies with the mean frequency covering the whole frequency range of interest. Results include the surge drift force and pitch drift moment. The results are presented in several stages in order to assess the influence of different phenomena contributing to the global second order responses. Firstly the body is restrained and secondly it is free to move at the wave frequency. The second order results include the contribution associated with quadratic products of first order quantities, the total second order force, and the contribution associated to the free surface forcing.


Sign in / Sign up

Export Citation Format

Share Document