Elixir Engineering was awarded to perform Safety Integration and Valve Criticality Analysis for Dhiab Infill Development Project
Dhiab Field is located 35km SW of the Marmul Field, onshore Oman in the South Oman Salt Basin. The field was discovered in 1985 and first oil was produced to surface in 1987. Dhiab structure is essentially a four-way-dip anticline, complicated by significant faulting.
The field is currently produced under water flooding, a mini water flooding experiment started in 2012 to test the response to flank water injection as a mean to increase field recovery, given the overall absence of strong aquifers to support pressure. The 2016 FDP suggested WF 5-spot development as the development mechanism which is implemented in the field since 2017. The main producing intervals in Dhiab are Middle Gharif, Lower Gharif and Al Khlata Formations, with total STOIIP of 16 million Sm3 as per 2016 FDP.
2016 saw the delivery of Dhiab's most recent FDP. Phase II development was covered. The development has a total of 48 2PUD wells. Inverted "9-spot" patterns, which are part of the CR project, and inverted 5-spot patterns with 250 m spacing for 2PUD.
As per June 2021 the cumulative oil production is ~ 1.44 MMm3, with expected developed and undeveloped reserves of ~ 0.54 MMm3 and ~ 0.57 MMm3 respectively. The total STOIIP expected was estimated at ~ 16.96 MMm3, yielding an expected recovery factor of 21% (currently around ~ 15%). The major items covered under this project scope are listed below, Project scope will be executed in 2 phases
Phase 1
Phase 2
Elixir Engineering has done the listed safety studies for Dhiab Infill project.
The process of Hazardous Area Classification (HAC) involves determining which elements of a facility are dangerous and which are not, as well as creating zones for the hazardous areas. A hazardous region is described as a three-dimensional place where it is reasonable to assume that a flammable atmosphere will exist at frequencies that necessitate particular safety measures for equipment design and construction as well as the management of other possible ignition sources.
Zone Classification: Zones are created in hazardous regions according to the probability and length of a flammable atmosphere.
Non-hazardous areas : Areas that do not occupy any of the above.
Source & Grade of release: Any region from which a flammable gas, vapour, or liquid may be discharged into the atmosphere is considered as a source of discharge for the purpose of area segregation. Based on their expected frequency and duration Three release grades are recognised.
Fluid Categories
Fluid | Description |
A | A flammable liquid that would quickly and significantly evaporate upon release. This group consists of: (a) Any lighter flammable liquid or any liquefied petroleum gas (b) Any flammable liquid at a temperature high enough to cause more than 40% volume to evaporate upon release when released, with no additional heat input from the environment. |
B | A combustible liquid that isn't in category A yet is hot enough to boil when released |
C | A flammable liquid, not in categories A or B, but which can, on release, be at temperature above its flash point, or form a flammable mist or spray. |
G(i) | A typical methane-rich natural gas. |
G(ii) | Refinery hydrogen. |
The goal of the FGDEA is to guarantee that the facility layout minimizes the possibility of escalation to the greatest extent that is practically practicable by identifying and evaluating plausible fire and explosion dangers. To evaluate the impact of believable leaks and determine the possibility of escalation, physical effects modeling (PEM) is used in accordance with PDO SP-1258 (Quantitative Risk Assessment Specification). The study evaluates the potential for impact on workers from hazardous and flammable releases as well as the physical impacts of hydrocarbon emissions, as specified by the potential sources of leakage (PSLs). The physical effects modelling carried out as part of the FGDEA will be used to optimize the Dhiab Infill Development Project and to mitigate escalation and achieve an inherently safe plot, as far as practicable, based on PDO SP-1127 & SP-1190 and confirm the suitability of the current layout of the Maintenance drain pit vent pipe based on the requirements in DEP 80.45.10.10-Gen.
The objectives of this study is as follows:
The overall study approach is summarised as follows:
Hazard Identification
HFE-VCA's goal is to outline the requirements for applying HFE concepts to valve design and layout, which includes the following:
Valve Criticality Rating
General
Valves are rated by criticality to help ensure that criticality valves are located to provide for rapid and effective identification and operation. The following three categories are recommended. Risk to health and safety—including the possibility of human error—must be maintained to a minimum.
Category-1 (C-1) Critical Valves
Included in the category of valves are those necessary for regular or emergency operations where quick and unhindered access is crucial. The next sections' descriptions of the "preferred" site must be followed in terms of height, reach distances, and visibility.
These valves satisfy any or all of the subsequent requirements:
Access Requirement for C-1 Valves
A permanent raised standing platform must be made available for accessibility. If steps are the only feasible means of access to the elevated platform, then access at ground or deck level is permissible.
The identification and state of valves must be easily observable from an approachable operator position, such as on a nearby walkway, access platform, or in the area surrounding equipment meant for human use.
Category-2 (C-2) Non-Critical Valves
Valves are employed in routine maintenance and inspection procedures, but they are not essential for regular or emergency operations. These valves satisfy any or all of the subsequent requirements:
Access Requirement for C-2 Valves
The "preferred" location, as shown in Figures 2 and 3, for C-2 valves should be the same as for C-1 valves in terms of height, reach, and visibility. C-2 valves may be located within the “acceptable area” as outlined in Figure 3, depending on their size and the force needed to operate them. A vertical fixed ladder and a small standing surface must be provided for access to C-2 valves in cases where ground level access is not justified.If adequate room and access are maintained for workers, tools, components, and equipment in the design, using auxiliary equipment (such as scaffolding, man lifts, or mobile platforms) to obtain access for maintenance reasons may be permitted.The operator may need to temporarily assume an awkward posture or reach areas not meant for human access in order to identify and inspect the state of C-2 valves, as long as doing so does not result in human error or place the operator in danger of harm or exposure to hazards.
Category‐3 (C-3) Non-operational Valves
Typically, valves are non-operating devices that are employed or examined in specific situations only seldom or infrequently (such as hot tap valves, hydro static test vents, high point vents, or low point drain valves situated in pipe racks), and they are not utilized in activities that are crucial to the HSSE.
Access Requirement for C-3 Valves
Although not necessary, constant access to and visibility of C-3 valves is preferred. No specific location requirements are imposed. Auxiliary equipment like as mobile platforms, human lifts, and/or scaffolding that are used to access C-3 valves must be specified and permitted in the design. C-3 valves should not be accessed with portable ladders. Any suggested exemption or exceptions to this will require careful consideration and approval. Height and reach distances to C-3 valves when operated from auxiliary equipment shall confirm to the “preferred” location.
Notes
Notes