A long journey from discovery to production Field development
It normally takes a few years before a newly discovered reservoir starts actually producing oil or gas. This phase is called field development and lasts until the production phase. At Wintershall there is a standardized process for this phase consisting of five stages.
Each of these stages ends with a gate. At this point the management decides whether the results gathered so far are promising enough to continue the field development and justify entering the next phase.
Field development in five stages
Identify Stage 1
The field development begins when the exploration phase ends: when an exploration well has made a discovery. Only this well can provide the certainty about whether crude oil or natural gas really does exist in the explored area after the seismic measurements have been conducted. When evaluation of the well data and analysis of the drill cores come to the clear conclusion that oil or gas has been found, this means a potential development project has been identified. The next phase, field development, can now begin.
Assess Stage 2
The aim of the assessment phase is to highlight the technical and commercial feasibility of the project.
To do so, it is necessary to find out as much as possible about the reservoir and to minimize the uncertainties. Measures that help to do so include other wells (appraisal), but also dynamic reservoir models. The reservoir engineers generate a 3D model of the subsurface so that they can estimate how much oil is hidden under the surface. Then, with the help of computer calculations, they can estimate the volume of oil or gas that can actually be produced.
The engineers plan the entire production phase and address all sorts of practical questions, such as: How many wells must be drilled and where? Can the oil be recovered to the surface in an on-shore project with a simple horse-head pump? Is the oil so corrosive that the pipes need a special coating? How can the maximum production volume be achieved – for example, by injecting water or gas into the reservoir? And when should this procedure begin?
In this phase, the reservoir engineers generate a 3D model of the subsurface.
Besides, the production volumes are simulated for the field's entire life cycle.
In this phase the project team also looks at the development options available and determines which production and treatment plants would generally be suitable and how the oil or gas could be transported once it has been produced.
Offshore fields offer even more development options.
For example, should the company build its own production facilities or can the field be connected to existing platforms via an underwater installation on the sea bed (a subsea tie back)? And if a platform is to be built: which is the most suitable? That depends on many factors, such as the water depth, the surrounding infrastructure and the necessary processing capacities..
Select Stage 3
The assessment phase has shown that there are many possibilities for developing a crude oil or natural gas field. Wintershall now examines all the development concepts in detail, compares them with each other and then decides which one to adopt. HSE plays a key role in this decision-making process. The safety precautions necessary for production, and the impact on the environment, are taken into account in the concepts and represent major factors that influence the decision.
The project team evaluates all the development options using criteria such as the production volumes expected, the necessary investments, operating costs, economic feasibility, HSE and the time needed until completion. Then the company management chooses the most suitable concept based on these criteria and makes the decision to develop this concept further.
There are many possibilities for developing a crude oil or natural gas field. For instance, you could select between a stand-alone platform, a subsea tie-back with an FPSO (Floating Production, Storage and Offloading) or a subsea tie-back that is linked to already existing host platforms. Eventually you will have to choose one.
Define Stage 4
Once the field development concept has been selected, the engineers take over the detailed field development and prepare the so-called Front End Engineering & Design (FEED). They now elaborate on the concept to include every last detail.
Using simulations and construction programs to help them, they draw up precise plans for the production wells that will recover the hydrocarbons, the production plants and the other infrastructure requirements, of the oil and gas produced.
Every last detail, no matter how minor, must be described meticulously: how big do the plants have to be? How should they be set up? What quality must the material used have? What sort of platform components do we need and where do we get them? How long will the construction, transport and on-site installation take?
So the engineers plan every single part of the platforms down to the last screw. Even though they try to use standard components for the oil and gas industry as much as possible, delivery of the individual components can take several months. The planning must therefore take this into account too. It is also vital that the contracts for materials, services, transport and marketing are in place. These are prepared and drawn up by the company’s procurement and legal teams.
At the end of the define phase the so-called “Final Investment Decision” is made: the management decides to develop the field for production.
Execute Stage 5
After years of preparation, the construction of the platform can now finally begin: for onshore reservoirs these are built on-site. If the reservoir is under the seabed, the offshore platform is built in a shipyard and the individual parts transported to their final destination. Logistics are extremely complex on the open seas: special ships with enormous cranes are required to build a new platform. They help to build the new platform level by level. Once everything is in place, the equipment is tested extensively by the authorities before being given the green light. Even this commissioning of a new production facility and the gradual process of reaching the planned production volume can take months.
The field development ends with the “first oil” or “first gas” – the start of commercial production. The new reservoir can now supply gas or oil reliably for decades.