How do you make offshore engineering decisions?

The written portions of knowledge to be imbibed is outstanding. May I humbly add that before successful operation begins: 1) check the reservoir characteristics for th HC quality and phase. The PI’s of contributing well will give an indication the potential to flow and factores such as Rs , viscosities , PARAFFINS/AROMATICS/ OLEFINS should be identified before execution of project starts. 2) beware of sand content!!! The wells PI’s and solution water may be an issue. 3) If LNG is in the picture , insure that gas mol wt. and predicted LNG Density are in order

When we talk about offshore engineering projects as opposed to conventional onshore oil & gas projects, the difference is the location : what water depth, sea state conditions : max. wave height, strong currents, tropical storms, arctic conditions, distance from existing port , marine support vessel etc. These parameters will affect the type of offshore facilities required, the cost of any marine operation during both construction, drilling and operational phases. The possibility of operating dry wells instead of subsea wells, will have a significant impact on the capital and operating costs of the offshore project.

I believe one thing to consider before landing on the right design is to make sure you look wide enough at the early stage during feasibility study and try to test different designs and concepts against the risks and uncertainties you have. Try with the simplest and cheapest design first and add features and complexities as needed to either improve value or to mitigate risk. This should eventually lead to the optimum and cost effective solution.

When we talk about offshore oil production system , we very often associate it with high capital cost and limited flexibility to the changing reservoir conditions and uncertainties. High capital costs to be economically sustainable need a steep production build up to a high plateau level. If our reservoir production predictions are underestimated, increasing production level is usually limited by the production facilities size , because offshore production facilities costs are related to equipment footprint size and therefore spare room for future equipment addition is usually not economically affordable. Subsea system are more flexible in this respect but they rely on the existence of hosts facilities in the vicinity.

Prior startup operations, Operator and Offshore installation management shall ensure: all necessary emergency plans had been designed and tested, Emergency equipment available and certified, Identify the necessity of external logistic support and ensure competence and expertise of the crew onboard. Important highlight that some emergencies could overpass the operational limit of the offshore unit and affect stake holders and communities on the line coast, therefore planning for this kind of emergencies require strong effort with local authorities, proper knowledge of the line coast, identification of community settlements and behavior of the oceanographic conditions according with the timing of the operations.

The offshore engineering design codes are mostly falling under the API, BSI , ISO and ASME standards. These internationally recognized design codes and standards however need to be verified against local country specific codes. Usually problems arise when we are in countries like the FSU ( former Soviet Union ) where different standards like GOST and SNIPS need to be complied. In general Environmental and Safety legislation of the country takes priority and needs to be complied with to receive the design certification by the local Authorities.

Analyzing complex engineering models at different conditions to verify the robustness of the design throughout the field operating life requires different tools and methods. A classical example is to perform hydraulic calculations of a waxy crude oil pipeline. In a waxy crude, the temperature along the pipe may drop and start to deposit wax and eventually plugging the line, unless suitable insulation and line heating are provided not only during normal operation but also during start-up and shut-down conditions, by using transient simulation software to calculate for how long the pipeline can stop flowing before plugging may occur or what preheating temperature is required when starting up the line.

One thing i found helpful to set as a team and implement decision tree to cover all possible scenarios of the operation then testing the uncertainity and how to mitigate this risk with safe operation decision. The whole team will refer to the decsion tree that has been implemented and your team thought and discussion will be very helpful prior to operation event, this make the operation more easier and understandable the problem situation and how to behave safely during this issue.

Look for synergy While looking for the best design, try to look at the nearby projects and see if there will be opportunity for synergy between your project and other ones. Synergy can save you time in execution or money in Capital expenditure (Capex) related to procurement or installation of offshore equipment, or the Operating expenditures (Opex) during the running life of your project .

Value Engineering decisions. During the concept design stage , many engineering decisions are made providing building blocks that all together define the design concept. By identifying each of these independent decisions and analyzing their value it will provide the rationale behind the development concept. For instance the decision to re-inject gas in the reservoir will add a certain value in terms of incremental oil recovery, will avoid the need to treat and export the gas through a pipeline. Usually the evaluation parameters are economics, HSE, operability, regulatory. By scoring each of these independent decisions it will help to define a sufficiently large set of concept to be evaluated.