Elixir Engineering was awarded to perform Engineering, Procurement, & Construction of Process Facilities Rearrangement at EWT Bejil for Petroweld
COMPANY is established to perform exploration and development of petroleum hydrocarbons in the Kurdistan Region of Iraq with under PSC’s with the Kurdistan Regional Government in Block 11 (Harir-Bejil).“Harir-Bejil Block” is located within the administrative border of Aqra, Soran and Shaqlawa District, approximately 56 kilometers north-east of Erbil and 114km south-east of Duhok/Kurdistan Region of Iraq. The Block covers an area of 1472 km2.
Existing Facility Description:
COMPANY has drilled the Bejil-1 well in Kurdistan and are planning to run an extended well test on the well to determine the size of the oil pool and develop a longer-term production plan for the pool. Sour oil, gas and potentially water are produced from the well through a short pipeline to a new facility is built near the well to separate the emulsion and produce a saleable oil product. The flow from the well Bejil-1 is controlled by a manual choke at the wellhead. The emulsion will flow through an underground pipeline to the facility.
At the Bejil-1 location there is a Manifold Skid SK-900 to allow two future wells to be connected to the same pipeline. This manifold skid includes individual ESD valves that can be closed by the Plant control system. The emulsion flows through a Basket Strainer ST-100A to remove any particulates in the well production fluids.
At the plant inlet, emulsion will first enter a Slug Catcher V-001 where the mixture will be separated into produced gas, produced emulsion and any free water that separates out. Any gas liberated in the slug catcher is directed to the HP flare knock drum (V-170) and then to the HP flare stack (FS-810). Any free water is directed to the produced water storage tank (TK-420). The emulsion from the Slug Catcher V-001 is then directed to the stage 1 heat exchanger (E- 200) where the mixture will be heated.
The emulsion will then flow to the Stage 1 Separator V-100 where any additional vapours are removed. The vapours will be directed to the HP flare KO drum (V-170). A part of the Stage 1 separator (V-100) gas will be routed to the storage tanks for blanketing purposes. The remaining oil and water in the separator then flow through a level control valve to the Stage 2 Heat Exchanger E-210 where the mixture is heated further.
A small of gas is liberated as the mixture is heated. This gas is removed in the Stage 2 Separator V-110, will be directed to LP flare KO drum and then to the LP flare stack (FS-800).
The remaining oil is then pumped (P-110A/B) to a large Demulsification Tank TK-400 where the mixture is allowed to settle. The water will migrate down in the tank and the oil will float up. If the first tank TK-400 is not able to complete the oil/ water separation and produce specification oil, then the oil mixture will be pumped to a second Demulsification Tank TK- 401 for further settling. Any clear water produced in the first tank TK-400 is pumped to the water tank TK-420. Similarly, clear water from tank TK-401 will also be pumped to the water tank TK-420. Clean oil from tank TK-401 will be pumped to the oil storage tank TK-410. If tank TK-400 can successfully separate the oil and water, then the clean oil from this tank will be sent directly to the oil tank TK-410. Tank TK-401 would then act as a backup tank if there are problems with Tank TK-400. The spec oil in TK-410 is then pumped into trucks through the loading stations and hauled away. The produced water is sent to a pond for evaporation.
Sour gas from slug catcher V-001 and Stage 1 separator V-100 is sent to the high-pressure flare knock-out drum V-170 and then to the high-pressure flare stack FS-810.
Sour Gas from Stage 2 separator V-110 is sent to the low-pressure flare knock-out drum V-130 and then to the low-pressure flare stack FS-800. A portion of this gas is sent to the tanks to fill the void in the tanks during the pump-out process. If this gas is not sufficient to maintain the sufficient pressure in the all tanks, extra gas will be sourced from 1st stage separator (V-100).
VRU blowcase (V-840) and Tank Vent blowcase (V-850) are provided along with new GES piping for the liquid fractions accumulation and draining from Gas Equalization System (GES). Gas Equalization system is a system of piping, Blowcases and VRU, designed to equalize the pressure in the gas spaces of De-Emulsification Tanks (TK-400/TK-401), Oil Storage Tank (TK-410) and Water Storage Tank (TK-420) to avoid oil losses from evaporation. VRU Blowcase V-840 is installed on the outgoing gas streams from the tanks TK-400, TK-401, TK- 410 and TK-420. Tank Vent Blowcase V-850 will be installed gas supply lines from V-110, V-100 and V-001. The liquid will be drained from the blowcase vessels by nitrogen under pressure.
The vapours off the tanks TK-400, TK-401, TK-410 and TK-420 are expected to contain high concentrations of H2S. These vapours are gathered and sent to a Vapour Recovery Unit (VRU) which compresses the vapours and sends them to flare.
During truck loading operation, any gas vented from the truck is collected by a Vent Gas Compressor K820 A/B. The compressed sour vent gas is sent to H2S scavenger vessel V820 where the H2S is removed. The resulting sweet gas is then directed to a vent stack VS-830. A Blow case vessel (V-860) is provided at truck loading area to collect the liquids from the loading arms. The collected liquids will be discharged to oil loading line.
Instrument air will be supplied to the plant users by instrument air system (IA-740). It consists of Air compressors, compressor air dryer and compressed air storage vessel. A nitrogen generating system (NG-710) will generate 95% nitrogen stream that will be used for purging when the plant is down and as a backup gas supply to the tanks so loading can take place when the battery is down for whatever reason.
A heat media system FH-710 will be used the heat the emulsion in the Stage 1 and Stage 2 heaters. The heat media will also be used to maintain temperatures on the tanks and some of the process equipment mostly in a battery shutdown situation.Primary and Secondary electric generators will supply power to the whole site.
Diesel is the fuel source for the plant. The electrical generators and the heat media heater are the main users for the fuel. The fuel is stored in a Storage Tank TK-430. The fuel is filtered (F-330) prior to the Pumps P-330 A/B and pumped to the heat media and gravity fed to the generators.The gas from the slug catcher, separators and VRU will flow to a flare knockout drum to remove liquids and then to the flare stack for burning.Drains in the plant will flow to a slop tank. When the tank is full, the pump will start and feed the “slop” to the battery inlet for processing.
Following facilities as per the Project scope are included in this HAZID study.
a) Replacement of the ТК-400/401/410/420 Gas Equalization System:
Gas Equalization System (GES) is a system of piping designed to equalize the pressure in the gas spaces of De-Emulsification Tanks (TK-400/TK-401), Oil Storage Tank (TK-410) and Water Storage Tank (TK-420) during pump-out (inbreathing)/ pump-in (outbreathing) operation to avoid oil losses from evaporation.
The following modification scope for GES system are as follows:
b) Rearrangement of the VST ТК-400/401 Intra-site Piping and Pumping Stations
c) New Roof at Oil Filling-in (Loading) Stations C/D and Roof to close gap between existing roof for Station A/B and new roof for Station C/D
d) New reinforced concrete bund and new Sun-roof for existing TK-430 Diesel Fuel Storage Tank and relocation of existing diesel fuel pumps.
Trace heating of all diesel fuel pipe lines (to main and emergency generators and oil Heat Medium Skid) shall be developed and implemented.
Elixir Engineering done different safety studies for EWT Bejil project.
The safety studies conducted for this project scope is listed below:
Objective
The overall intent of an HAZID study is to assist in demonstrating that the risk associated with all the identified hazards are managed and will be reduced to an acceptable level by:
HAZID is a structured review technique for the early identification of all significant hazards associated with the particular activity under consideration. HAZID is carried out by a systematic analysis of all the threats with the potential to generate health, safety, environmental, asset risks. Once the hazards have been identified, the associated risks are qualitatively assessed and risk prevention and mitigation measures identified in consistency with the adopted Risk Management strategy.
In this workshop, emphasis was on identifying any hazards introduced by activities related to the Project. However, attention was paid to the interactions between the existing facility and their impacts on the project.
HAZID methodology
Many of the hazards and HSE issues are generic for the whole development and are not specific to any part of the plant or location. The procedure is firstly to apply the technique to the whole development as a single entity, as far as possible, and then review discrete areas as appropriate.The study method is a combination of identification, analysis and brainstorming based on the hazards identified with the help of a checklist of potential hazards.
The main topics covered by the checklist are
The HAZID review proceeds as a structured brainstorming of potential hazard scenarios using proper guidewords; the HAZID Checklist is comprehensive but not exhaustive and the use of brainstorming to identify novel or unforeseen hazards may be required.
The HAZID Facilitator will examine the system against the Checklist and within each Checklist section; for each potential hazard that is identified, the specific threat (or cause) and its associated consequences are derived. The adequacy and presence of the existing safeguards (either preventive or mitigating) are assessed and finally, the risk associated to the hazardous event is evaluated with the support of a COMPANY Risk Matrix. Recommendations for reducing risks are identified during the brainstorming, in consistency with the applied risk management process.
Hence, the following review process shall be facilitated
Steps (2) to (6) are repeated until all applicable guide-words have been exhausted and the team is satisfied that all significant deviations have been considered.
HAZID Basic Rules
The following ground rules are set before proceeding with the HAZID Session
Hazard and Operability (HAZOP) Study is a structured and systematic evaluation of a planned and/or existing operation to identify and evaluate potential hazards in design and operation. This study is carried out by a team of engineers from different disciplines.
The team looks at each section of a plant or system or operation (node), considers potential deviations from intended operation and analyses their consequences against any existing safeguards. Impact of identified hazards on safety, asset and environment are assessed.
HAZOP is a guideword driven brainstorming technique. Team members contribute based on their collective experience and lessons learnt from past projects.
HAZOP study records the identified hazards without proposing any solution, unless a solution is obvious.
Proposed solutions may include additional safeguards or operational procedures as necessary.
The study record serves as a guide to determine the Health, Safety and Environment (HSE) issues to be resolved during the project.
Purpose of HAZOP
HAZOP for any project or modification serves many purposes including
Methodology
The HAZOP focuses on the process / utility system and associated interfaces. The basic concept of a HAZOP study is to take full description of the process and question every part of it during brain storming meetings attended by the different specialists involved in the process design to discover firstly what deviations from the intention of design can occur and what their causes and consequences may be.
The main steps involved in a HAZOP study are as follows
Elements of HAZOP Study
Node definition
The HAZOP study progresses through the plant node by node. The selection of the node sizes and the route through the plant is made before the study by the facilitator. The node should be described in terms of: -
Parameters
Flow, Pressure & temperature are usually regarded as the main parameters/elements. Additional parameters relate to general considerations like maintenance, safety, relief, corrosion/ erosion, instrumentation, start-up & shutdown, etc. Some of these may be selected for nodes in a study as appropriate based on relevance and concerns expressed by team members.
Guidewords
Guide words are simple words or phrases used to qualify or quantify the intention and associated parameters in order to suggest deviations.
Standard guide words; No/less, more/Less, As Well As/Part of, Reverse/Other Than, Early/Late, Before/After are applicable to each parameter. ‘Other Than’ is a very popular ‘catch all’ guide word at the end of each parameter
Causes
All credible/ possible scenarios leading to the deviations should be considered when determining causes. The Causes should be “Local” to the node being studied. The consequences are deliberated only after listing all the Causes. Two events happening simultaneously without any correlation should not be considered.
Consequence
“Global” effects should be considered for the consequences i.e., keep researching the resulting reactions till you reach the Ultimate Consequence of a deviation.
Safeguards
Risk is a function of both Probability and Consequence. Safeguards reduce either Probability or Consequence.
These could be either related to hardware or operator practices & intervention., While selecting safeguards, you may consider engineering or administrative safeguards, but it is necessary to check whether these are existing & functional for the operating plant.
Recommendations
Recommendations should be reported using action-based words (such as Check, Provide, Consider, Ensure, Review etc.), and assigned to specific work groups. It should be verified whether three chief questions have been explained, viz.
Objective
The SIL (LOPA) Study is undertaken on safety systems for the purpose of defining a SIL (Safety Integrity Level) rating for Safety Instrumented Functions (SIFs). The SIL rating of a SIF defines the integrity specification (and hence the minimum reliability requirement) and architectural requirements for SIF equipment. The SIL Classification process may be implemented to determine whether the existing or proposed design meets the integrity specification and if not, what changes are necessary to meet the integrity specification.
The following table provides the target performance requirement for each SIL as based on the definition in IEC 61511-1.
| SIL | Low demand mode of operation | Risk Reduction Factor (RRF) |
| 4 | ≥1x10-5 to <1x10-4 | 10,000 to 100,000 |
| 3 | ≥1x10-5 to <1x10-4 | 1,000 to 10,000 |
| 2 | ≥1x10-5 to <1x10-4 | 100 to 1,000 |
| 1 | ≥1x10-5 to <1x10-4 | 10 to 100 |
The following information and steps are required to perform the assessment of a given SIF
Main part of the information described above is based on the HAZOP findings.
Following the steps illustrated in the figure above, the SIF’s required SIL can be determined by means of the next sequence:
| Consequence scale | TMEL |
| C1 Negligible | 10-2 [ev/y] |
| C2 Minor | 10-3 [ev/y] |
| C3 Moderate | 10-4 [ev/y] |
| C4 Major | 10-5 [ev/y] |
| C5 Extreme | 10-6 [ev/y] |
There shall be individual TMEFs for Safety consequence, Environmental consequence, Asset damage consequence and Reputation consequence.
PFD = TMEL / Total MEF
RRF = 1 / PFD
In case of more than one cause or consequence, the highest RRF or SIL requirement shall apply for the respective SIF.
SIL (LOPA) Main Parameters
The following sections show the main parameters to be assigned in each SIF Classification.
Initiating Events Likelihood Estimate
Initiation likelihoods for some typical failures are reported in the following table. Likelihood of more complex/specific initiating causes will be determined during sessions on the basis of the judgement and experience of the Team.
The following parameters can be used as conditional modifiers in LOPA scenarios wherever applicable. It may be noted that, to avoid double accounting, they should not be used as IPL if they are considered as conditional modifiers:
The following rules and values will be used when selecting and assessing the Conditional modifiers to be used for the LOPA.
Independent Protection Layers are divided in the following groups:
All the Protection Layers described above shall be characterised by their relevant Probability of Failure on Demand (PFD) in order to determine the risk reduction potential associated to each of them. The suggested values of Probability of Failure on Demand (PFD) to be used for the identified IPLs are summarised here below:
COMPANY risk matrix will be used to qualitatively assess the consequence, likelihood and risk associated with the identified hazards.It shall be bear in mind that the method adopted will be capable of effectively classifying hazards, but without taking too much time or distracting the team from their primary focus.A five-category system will be used both for consequences likelihood and magnitude classification. In case of multiple consequences for the same deviation, the ‘worst case’ should be selected.
Since the ranking exercise can be very time consuming, it is suggested that, in case of tight schedule due to prolonged discussion, only the worst risk ranking could be recorded among the consequence categories mentioned in the matrix.
Probabilities will be estimated according to the following scale, as per COMPANY's Procedure:
