BRIEF SUMMARY OF JU CONFERENCE PAPER ON INNOVATIVE RIG MOVE APPROACH
by J. Vazquez
October 30, 2019
The 2019 International Jack up Conference took place on September 11 and 12 at City University in London. Although this time around, I did not present any papers, I am happy I attended the conference, as I got to meet with old friends as well as make a few new acquaintances. Below, I present a brief overview of a very interesting paper, “Paradigm Shift in Managing Safe and Efficient Jack-Up Rig Moves Through Engineering and Operational Excellence authored by K. Burana, C. Jantarawaranyoo, O.A. Purwana and N.R.G. Sabin. The paper provides the specifics of a new way of managing jackup rig moves and the positive results for its implementation. I offer my sincere thanks to presenting author, Okky Purwana, now a professor at the National University of Singapore, for giving me permission to publish this overview and its accompanying images. Okky can be reached by email at firstname.lastname@example.org.
The paper presents specifics of an innovative rig move approach used in 2017-2018 for an asset retirement campaign in the Gulf of Thailand. The jackup used for these operations was the “Ao Thai” jackup, at the time part of TRANSOCEAN’s fleet. The campaign was to decommission over 6,000 wells on more than 300 wellhead platforms in geotechnically challenging locations, with a target completion time of 20 months for Phases 1&2 (Plug and Abandonment of the wells) covering 10% of the total wells. The authors attributed the success of the P&A campaign to the synergy between the rig owner and the MWS counterpart through continuous improvements culture, effective engineering and continual feedback process throughout rig move preparation and executions.
The two paragraphs below are a direct quote from the paper’s introduction section. I post them as originally written because I don’t think I can eliminate any of that information while still giving a complete picture of the conditions that required the innovative rig move approach.
In order to meet the project economics, the overall procedure and cost of the P&A operations needed to be optimized beyond the historical performance of approximately one day per well. Based on past P&A operations within the asset, the rig move cost was estimated to constitute 30-40% of the total project cost. Rig move records from the past operations within the asset suggested that, on average, a total of seven days was required to move a rig from one platform to the next, taking into account time spent waiting on weather and the complexity of rig installations in the majority of the platform sites at the Gulf of Thailand. A shorter rig move duration was therefore targeted at an average of three days per move, to help reduce the total cost of the relatively short operation at each platform.
Besides the project commercial demands, the marine operations also faced technical challenges, mainly due to geotechnical characteristics of the platform locations. The majority of the platform locations posed considerable geotechnical hazards which would normally necessitate more precautionary procedures, leading to an extended rig move time for assuring the safety of the installation. Managing safe and efficient jack-up rig moves for the P&A campaign at such geotechnically challenging locations in a consistent and timely manner therefore demanded a step change in rig move planning and execution.
I note that Figures 1-3 and Figure 5 presented below are not from the paper itself, but from Okky’s presentation.
Figure 1 shows the “Ao Thai” jackup, the Gulf of Thailand where the rig moves were to take place and the number of well completions and number of platforms for this campaign.
Figure 2 shows the characteristics of the “Ao Thai” jackup, a KFELS-designed “Big Foot, Super-B” B-Class jackup. [Note from JV: The Big Foot refers to the larger spudcan size than the standard B-Class spudcan size, while the Super-B refers to the fact that unlike most, if not all, other B-Class jackups, this design has 3 rounds of pinions. There is a different B-Class design that is also referred to as the “Super-B”, but that design had a fixation system and it standard size spudcans].
Figure 3 shows some of the geotechnical challenges encountered during the campaign.
Figure 1 – Jackup, Region and Specifics of the Well Completion Campaign
Figure 2 – Characteristics of the “Ao Thai” jackup
Figure 3 – Geotechnical Challenges
The authors clearly state that key to the success of the innovative rig move approach was the synergy between the TRANSOCEAN “Ao Thai” team and the Noble Denton Marine Services team, as they prepared, executed and monitored each rig move.
Figure 4 shows a flowchart of the enhanced workflow between the drilling contractor and the marine warranty surveyor for which extra steps are added including an intelligent use of historical data and relevant experiences;
real-time monitoring and continual feedback between the on-board marine team and onshore engineering specialists; and continual improvement on safety and efficiency for future operations.
This is noticeably different from the standard approach, summarized below, quoting directly from the paper.
Upon request from drilling contractor (the insured), the involvement of a marine warranty survey (MWS) typically begins with location review based on supplied site information and the vessel’s marine operations manual. As well as document review, additional engineering may be performed by the MWS to better assess the suitability of the proposed rig for the intended activities at the location in question. Upon satisfactory outcome, a certificate of location approval is issued by the MWS together with a summary of the review study and recommendations. The drilling contractor develops a rig move procedure considering the conditions and recommendations outlined in the location approval. During the rig move, a marine warranty surveyor attendance onboard the rig is often requested, to witness the rig move execution; to assess the compliance to the MWS-approved rig move procedures; and to confirm that the final as-installed condition meets the parameters specified in the location approval. Should there be any deviations, the as-installed condition may be reassessed, and if still satisfactory, the location approval can be reissued by the MWS.
Figure 4 – Enhanced workflow between drilling contractor and marine warranty surveyor
Quoting again directly from the paper, the below paragraph summarizes the success of the innovative rig move campaign.
In October 2018, the “Ao Thai” jack-up rig completed the P&A operations at the 32 platforms after a 20-month long campaign. A total of 604 wells were delivered successfully, exceeding the initial target. The volume of the “Ao Thai” rig moves for the P&A campaign was equivalent to twice the total number of rig moves of the other four jack-up rigs operating within the assets during the same period.
Figure 5 presents a summary of the successful results. It is noted that the bulk of the savings came from improved P&A operations (reducing average required time per well from 1.1 days to 0.4 days), the rig innovative rig move approach ended up speeding up the average time for a rig move from 7 days to 3 days.
Figure 5 – Successful Results from the 20-month P&A Campaign