Prediction of the Financial Losses of Subsea Pipeline Failure

The consequences of subsea crude pipeline failure drastically affect the continuity of oil supply and the ability of operating companies to meet market demand. Moreover, it reduces clients’ confidence and reliance on operating companies. There are mainly two types of failures that severely affect the integrity and operability of a pipeline. These are the leakage caused by gradual thinning of the pipeline due to corrosion and the leakage caused by a rupture pressure. The first form of failure results in a constant slow leakage that go over time without being noticed. While the second form of failure takes place without warning which makes the restoration effort extremely difficult and time consuming. Both forms of failure result in delayed production, environmental damage, legal claims as well as financial losses that operating companies could incur. Moreover, leaked oil products adversely impact other industries which bring these industries into a halt. Such industries may include fishery, maritime transportation, and tourism industries. This paper presents a method for predicting the financial losses that a company could incur in the event a corroded pipeline undergoes the abovementioned failures. Basically, this method can be used as a standard estimating tool for predicting the financial losses if such events occur.

ANALYSIS OF THE BASIC DIRECTIONS OF FIRE HOSES RUPTURE PRESSURES INCREASING

The analysis of the main ways to increase the rupture pressure of these technical products was made based on the rupture pressures dependence in fire pressure hoses from the parameters of their woven reinforcing frame previously obtained by the authors. From a scientific and practical point of view, the main directions for increasing the bursting internal pressures in the FPH (Fire pressure hoses) are identified and analyzed. The developed methodology for calculating and designing of FPH is based on a relationship connecting internal hydraulic pressure p-burst with a breaking load N-burst in the weft thread and a number of other parameters. To assess the influence of the parameters of the FPH woven reinforcing framework on the value of the internal bursting pressure, the latex FPH with a diameter of 77 mm manufactured by BEREG (Russia) made of polyester yarns and designed for a working pressure of 1.6 MPa, was chosen as the object of study. The dependences of the bursting pressures values on the bursting strength of weft threads of FPH woven reinforcing frameworks, designed for a working pressure of 1.6 MPa, for various diameters of the arms cross sections are obtained. The influence of geometric densities on the basis and weft of the woven reinforcing frame on the value of internal burst pressure in the FPH is investigated. When calculating the FPH strength under the action of internal hydraulic pressure, the effect on the value of the burst pressure in latex FPH manufactured by BEREG (Russia), designed for a working pressure of 1.6 MPa, such parameters as sleeve radius, geometric densities of base and weft was studied. When designing and creating new types of FPH, it is necessary to take into account the influence of these parameters on the burst pressure value.

Estimation of the Load Carrying Capacity of the Bellows Compensator for Gas Pipelines in the Areas of Mining Production

The stress state of pipelines in areas of mine production requires obligatory consideration the influence of ground displacements. In this case the rules for design pipelines include the additional actions, such as the wall thickness increasing or U-shaped compensators installation. The Ukrainian coal mining industry requires the expanding of mine production areas. It leads to the situation where old pipelines, which are not designed for such loads, could rupture due to ground displacements. The principle of “extinguish a fire” is applied in this case. It consists in applying of stress reduction actions before certain stage of mine production (so-called lava), such as digging out long sections, cutting and sanding, which require the involvement of significant human and material resources. But, in some cases, even the large-scale application of these actions does not lead to the stress reduction to the acceptable level (especially for pipelines of diameter less then 200mm). So, to solve this problem the implementation of bellow compensators (BC) is proposed. The present work consists of: • experimental investigations of BC which are carried out in order to obtain its bearing capacity and to validate its designed parameters guaranteed by the manufacturer; • simulation of the BC loading process using FEM with adjusting the way of contact modelling between the BC layers in such manner, to be best correlate with the results of experiments; • the application of obtained results for modelling of stress state of real pipelines in the areas of coal mine production. The results of experimental investigation of BC of DN100 is presented. Their include: hydrotest with axial displacements limitation; tension-compression cycles for different values of amplitude with simultaneously loading of the operating value of gas pipeline internal pressure; rupture pressure determination. Based on the experimental results, numerical modelling and specified domestic software for stress state assessment in pipelines the optimal locations and the required number of BCs is determined for buried gas pipelines. The results of presented works allowed us not only to implement the BCs to gas pipelines DN100 in areas of mine productions, but also the necessary experience for creation of larger diameters BCs is obtained.

Prediction of the Rupture Pressure of Transmission Pipelines With Corrosion Defects

This paper investigates the rupture of thin-walled ductile cylinders with isolated corrosion defects, subject only to internal pressure. It aims to propose a new solution for predicting the maximum load limit that will rupture a corroded pipeline, regardless of its material, its geometric ratio, or the dimensions of the existing corrosion defect. This solution is the result of several numerical simulations by variation of the length and depth of the defect with the assumption that the width of the defect has a negligible marginal effect. In all our numerical simulation analyses, the rupture was controlled by the Tresca failure criterion which is expressed in terms of material hardening exponent and the ultimate material stress. The proposed solution was then compared with the currently used coded methods, first B31.G, its improved version 0.85dL, and then DNV-RP F101, using an experimental database compiled from the existing literature. As a result, our proposed solution has been validated and has resulted in rupture ratios ranging from approximately 0.7 to 1. Furthermore, it has a tight prediction range compared to the B31.G, 0.85dL, and the DNV-RP F101 methods.

Ductile Rupture Pressure Prediction for Capped-Open Casing and Tubing Under Combined Loads

Casing and tubing is widely used as protective conduits during all the phases of operations and productions for the oil and gas industry. Recently, casing and tubing burst failure accidents often take place in high pressure and high temperature (HPHT) oil and gas wells during production. Therefore, it is very important to accurately predict casing and tubing bust strength in the casing and tubing design and operation process. PD CEN ISO-TR 10400 presents the ductile rupture model for capped-end conditions, but capped-end casing and tubing applied in oil fields is few. For this case, this document establishes the ductile rupture model for capped-open conditions under combined loads on the base of PD CEN ISO-TR 10400. Numerical and experimental comparisons show that the ductile rupture model for capped-open conditions under combined loads prediction values essentially coincides with burst data provided by PD CEN ISO-TR 10400.

Experimental determination of rupture pressure and stress of adventitia of human middle cerebral arteries

Background Intracranial arterial dissections might be attributed to the particular biomechanical properties of their specific layers. Also, knowledge of adventitia properties would be crucial in the context of intracranial balloon angioplasty. Aims The purpose of this work was to determine the rupture pressure of separated adventitia and compare it to intact cerebral arterial segments. Methods Brain specimens were harvested from 14 autopsy subjects (age range from 23 to 86 years). Pressure-inflation tests were conducted on proximal segments of middle cerebral arteries and separated adventitia layers from contralateral arteries to assess the rupture pressure values. Results The averaged rupture pressure of adventitia layers was 1.41 SD 0.25 atm (1072 SD 190 mmHg), whereas for intact arterial segments it was 2.32 SD 0.70 atm (1763 SD 532 mmHg) and diminished with age according to nonlinear regression trends. The difference beetween the aformentioned rupture pressures was positively correlated with rupture pressure of intact arterial segments ( R2 = 0.88; p < 0.001). Conclusions The obtained experimental results indicate a leading role of adventitia in building arterial strength under supraphysiological pressure conditions. The greater the rupture pressure of complete cerebral arteries, the smaller the contribution of adventitia in overall wall resistance.

Technological Properties of Wheat/Trifoliate Yam (Dioscorea dumetorum) Hardened Tubers Composite Flours

The ability of trifoliate hardened-yam flours to partially substitute wheat flour in food formulations was assessed. Three varieties of hardened-yam flour were incorporated in wheat flour in proportions of 0, 10, 20, 30, 40, and 50% (w/w). Samples were evaluated for protein content, Zeleny sedimentation index, Hagberg falling number, functional properties (WAC, WSI, and OAC), and some rheological properties including dough rupture pressure (P), extensibility (L), stability (P/L), and deformation energy (W). Results showed that trifoliate hardened-yam flours do not have acceptable baking properties as pictured by the low Zeleny sedimentation index and the low Hagberg falling number. Protein quality (Zeleny index, 31) of wheat flour helped to compensate gluten deficit of yam flours, but the amylasic activity determined by the Hagberg falling number could not be adjusted, which resulted in a loss of extensibility (L) of the paste at 10% substitution. Multivariate analysis of experimental data regrouped wheat flour and all wheat/hardened-yam treated with kanwa composite flours in one homogeneous cluster. Although wheat/hardened-yam treated with kanwa composite flours had physicochemical and functional properties similar to wheat, the inadequate diastasic activity makes them inappropriate for bread making, marking the strongest influence of that parameter.

Low-Salinity Chase Waterfloods Improve Performance of Cr(III)-Acetate Hydrolyzed Polyacrylamide Gel in Fractured Cores

Summary Polymer gels are frequently applied for conformance improvement in fractured reservoirs, where fluid channeling through fractures limits the success of waterflooding. Placement of polymer gel in fractures reduces fracture conductivity, thus increasing pressure gradients across matrix blocks during chase floods. A gel-filled fracture is reopened to fluid flow if the injection pressure during chase floods exceeds the gel-rupture pressure; thus, channeling through the fractures resumes. The success of a polymer-gel treatment, therefore, depends on the rupture pressure. Salinity differences between the gel network and surrounding water phase are known causes of gel swelling (e.g., observed in recent work on preformed particle gels). Gel swelling and its effect on fluid flow have, however, been less studied in conjunction with conventional polymer gels. By use of corefloods, this work demonstrates that low-salinity water can swell conventional Cr(III)-acetate hydrolyzed polyacrylamide (HPAM) gels, thereby significantly improving gel-blocking performance after gel rupture. Formed polymer gel was placed in fractured core plugs, and chase waterfloods were performed using four different brine compositions, of which three were low-salinity brines. The fluid flow rates through the matrix and differential pressures across the matrix and fracture were measured and shown to increase with decreasing salinity in the injected water phase. In some cores, the fractures were reblocked during low-salinity waterfloods, and gel-blocking capacity was increased above the initial level. Low-salinity water subsequently flooded the matrix during chase floods, which provided additional benefits to the waterflood. The improved blocking capacity of the gel was caused by a difference in salinity between the gel and injected water phase, which induced gel swelling. The results were reproducible through several experiments, and stable for long periods of time in both sandstone and carbonate outcrop core materials. Combining polymer gel placement in fractures with low-salinity chase floods is a promising approach in integrated enhanced oil recovery (IEOR).