Slug Taking care of Framework on NQ Stage - A Contextual analysis for C-Arrangement Pipeline Seaward Designing Administr.


96 views
Uploaded on:
Category: People / Lifestyle
Description
Slug Taking care of Framework on NQ Stage - A Contextual analysis for C-Arrangement Pipeline Seaward Designing Administrations ONGC Ltd. Mumbai Back Ground C - Arrangement fields lie 60 km. West of Daman.
Transcripts
Slide 1

Slug Handling System on NQ Platform - A Case Study for C-Series Pipeline Offshore Engineering Services ONGC Ltd. Mumbai

Slide 2

Back Ground C - Series fields lie 60 km. West of Daman. Includes for the most part Gas bearing structures viz. C-39-8, C-39-6, C-39-1, C-26, C-24, C-23, C-22, B-12-7 and B-12-1. Water profundity variety 19m-30m. Every structure has restricted creation limit Short generation life.

Slide 3

Facilities to be made The Scheme should be finished in three stages : Total Unmanned Well Platforms : 8 Nos. Stage I -4 ( C-22, C-24, C-39-1 & C-39-A) Phase I (with the exception of pipelines) dispatched in April 2009 Phase II (5 th Year) -2 ( C-23 & B-12-7 ) Phase III (11 th Year) -2 ( C-26 & B-12-1 )

Slide 4

Pipeline system for C-Series C-39-A C-39-1 Phase-I 8”X 2.5 km Phase-II 22” X 60 km C-39-A to C-24 C-23 Phase-III 8” X 3 km C-22 C-24 8” X 2.5 km 8” X 2 km C-26 B-12-1 C-24 to NQG 28” X 115 km 8” X 3 km 8” X 2 km B-12-7 Existing NQG Proposed Uran

Slide 5

Production Scenario (Peak Rate) Gas, MMSCMD Condensate, M3/HR Phase I - 3.20 28.33 Phase II (5 th year) - 3.58 67.00

Slide 6

Brief Description of the Pipeline System C-Series pipeline is 175 km. long having breadth of 22” & 28” The pipeline begins from C-39-An and runs upto C-24 with a width of 22” and separation of 60 Km. The line further begins from C-24 and closures at NQG with a width of 28” and separation of 115 Km. Seabed on the pipeline course slants down continuously from 20 m at C-arrangement end to 60 m at NQG end The pipeline has been intended to transport 3.58 MMSCMD gas and 67 m3/hr condensate from the minimal fields to NQ process complex.

Slide 7

Bathemetry of Pipeline course

Slide 8

Slug Flow What is slug stream ? Slug stream is a two-stage stream design which is portrayed by a succession of packs of fluid isolated by long gas air pockets streaming over a fluid film inside the channel and is ordinarily connected with high weight drops. How slug is framed ? Slug arrangement is a wonder which is ordinarily seen in long separation pipelines having uneven landscape (called territory sluging) and/or pipeline id much higher than that needed for typical through-put (called hydrodynamic slugging) Implications of slug stream on getting offices Unless measured properly, the slug stream may bring about operational irregularity and even cause creation misfortune or facilities’ close down

Slide 9

Study Description A dynamic reenactment of the pipeline was helped out through Scand Power Technology, Dubai utilizing their Olga Software to find out the likelihood of slugging of the pipeline under different working situation. The study\'s target were to focus the pipeline\'s slugging under different working situation like diminished stream, close down, re-begin and creation incline up.

Slide 10

Simulation Scenarios with a specific end goal to advance the quantity of reenactments, taking after run of the mill cases were reproduced utilizing Olga programming. Consistent generation rates: Considering 25%, half, 75% and 100% of most extreme creation rates for Phase-I & Phase-II. Turn down Simulation: Reducing the creation rates under Phase-II from 100% to 75%, 75% to half, half to 25% Shut-in Simulation: Shutting down the Production under Phase-II of every source all the while from 25% to non streaming condition. Re-begin Simulation: Restarting the creation from non-streaming condition to 25% and non-streaming condition to 100%. Incline up Simulation: Increasing the creation from 25% to half, half to 75%, 75% to 100% and 25% to 100%.

Slide 11

Result of different situations reproduced CONSTANT PRODUCTION RATES 1) It is watched that higher the creation rate, lower is the fluid substance in the pipeline. Gentle territory slugging was seen at upstream closures i.e. well heads, for 25% generation rate for both, Phase-I and Phase-II. Most extreme fluid substance saw in the pipeline ( 2764 m3 in Phase-I and 3295 m3 in Ph-II). No slugging was seen at the downstream end at NQG and liquid entry rate at NQG was observed to be well inside of the taking care of limit of NQG topside offices. 4) Slug stream brought about well head weight vacillations of approx. 1 bar. The slug recurrence was approx. 1 slug for each day for Phase-I and 2.8 slugs for every day for Phase-II. Contd.

Slide 12

Result of different situations recreated (contd.) TURN DOWN SIMULATION It is watched that higher the turndown, higher is the ideal opportunity for fluid substance to get settled. 265 hrs. (~11 days) are needed for fluid substance to get balanced out in 28” C-24-NQG pipeline when generation rate is decreased from 100% to 25%. Though adjustment takes around 70 hrs. (~3 days) when generation rate is decreased from 100% to 75%. No slugging was seen amid the adjustment period for any turndown case.

Slide 13

Result of different situations mimicked (contd.) SHUT IN SIMULATION It is watched that after the wellheads were closed in for 11.5 hrs, the riser base towards NQG was totally topped off with fluid because of down incline geometry of the pipeline towards NQG. Following 24 hours close in, the fluids had totally filled segment from KP 110.63 to riser base having funnel volume 175 m3. Besides, the channel from KP 108.85 to KP 110.63 was somewhat filled represented 273 m3 fluid from KP 108.85 to the riser base. The fluid amassing towards riser base at NQG offers ascend to slug upon restart. It was likewise watched that higher the time of shutdown, higher is the volume of slug upon restart.

Slide 14

Result of different situations recreated (contd.) RESTART SIMULATION 1) Both 100% and 25% restart brought about slug stream and were past the NQG taking care of limit. Decreased restart stream rate does not have much effect with the exception of dragging out the landing rate of slug. 2) Liquid slug was likewise trailed by gas surge of extent much higher than the outline limit of the topside offices. 3) For restart to 100% generation case, the fluid rate surged to a top worth following 3 hours had gone since stream was continued. The aggregate fluid surge volume in abundance of taking care of limit (~100 m3/hr) was 269 m3 and the handling time needed was 3 hrs. A gas surge of greatness 16 MMSCMD (for a brief length of time) trailed by fluid slug of 12758 m3/hr (for a brief term) was additionally watched. Consequent surges were observed to be inside of the taking care of limit. Contd.

Slide 15

Result of different situations reproduced (contd.) RESTART SIMULATION For restart to 25% creation case, the fluid rate surged to a top quality following 9.3 hours had gone since stream was continued. The aggregate fluid surge volume in abundance of taking care of limit (~100 m3/hr) was 286 m3 and the preparing time needed was 3.5 hrs. A gas surge of extent 11 MMSCMD (for a brief span). taken after by fluid slug of 16688 m3/hr (for a brief span) was likewise watched. A resulting gas surge of equivalent size was watched at10 th hour. It is likewise watched that any shutdown more prominent than 1 hour will create slug on restart. Nonetheless, extra restart recreation is obliged to measure the same. Contd

Slide 16

Result of different situations recreated (contd.) RESTART SIMULATION 6 ) Experienced speeds surpassing erosional speed proportion by an element of 1.1 in C-24 22” riser amid 100% restart operation. Nonetheless, erosional speed point of confinement was not surpassed in the pipeline system. 7) Experienced speeds surpassing erosional speed proportion by a component of 1.4 in C-24 22” riser amid 25% restart operation. The normal speed did not surpass the erosional speed point of confinement but rather because of slug stream, the gas speed promptly surged past the erosional speed.

Slide 17

Result of different situations mimicked (contd.) RAMP-UP SIMULATION Ramp-up in steps i.e. expanding the creation from 25% to half, half to 75% and 75% to 100% permitting the stream to balance out after every augmentation don\'t bring on any slug stream at NQG. Such increase from 25% stream rate to most extreme generation rate could be accomplished in 3 days. The fluid surge for 25% to 100% slope up was observed to be most noteworthy volume of incline up surges investigated. The fluid surge volume created was in overabundance of NQG taking care of limit. Amid 25% to 100% incline up, erosional speed cutoff was surpassed for few sections of pipeline system. Amid consecutive increase, erosional speed point of confinement was just surpassed in C-24 22” riser.

Slide 18

Recommendations for conceivable therapeutic measures Increasing taking care of limit prompting diminishment in time needed to process fluid surges. Usage of topside gag prompting diminishment in surge volumes inside of the present vessel volumes and taking care of limit rates.

Slide 19

Implementation of the Scheme Since the stage offices have as of now been placed set up, any expansion of offices for expanding limit would include time and expense. This would bring about postponement in appointing the plant or shutdown for long length of time. Containing the surge stream at the delta with stifle/control valve for the term that the surge is expected is most sensible answer for the issue. The P&ID (Piping and Instrumentation Diagram) of the procedure before the slug control plan is executed is appeared in the following slide.

Slide 20

Implementation of the Scheme (Before Slug Control)

Slide 21

Implementation of the Scheme

Slide 22

Implementation of the Scheme (contd.) A shutdown\'s mix valve and control valve on the detour line would guarantee safe operation amid the start-up of the line after a shutdown. 6” control valve has been discovered suitable for the slug\'s control stream and irregular gas stream. Any lower size would turn into a requiremen

Recommended
View more...