Its very intense, lots of long hours like 36 hr workdays and on call jobs in cementing. I worked here as a field engineer and it was very rough. Lots of long days, no sleep and eating and sleeping on the road.
For your first weeks at Schlumberger, you are required to undergo the New Employee Safety Training (NEST) and are provided Personal Protective Equipment (PPE).
Afterwards, for my training I went on short rotations between different segments (Cementing, D&M, Wireline and Mud). For the cementing engineer, it mainly consisted of lab testing different materials to prepare the perfect cement substance for the well, while also making a few visits to the rig site. The visits were to introduce cement to the empty circular space between the well-bore and casing in the drilled oil well. For the drilling & measurement engineer, your daily routine is either one of the two. Either you are required to troubleshoot faulted D&M tools in the lab at the base site, or you are sent to the rig site (which is in the middle of nowhere, very far from civilization) to monitor the performance of the drilling tools down the well. The field D&M engineer is required to negotiate and engage in conversation with the field site manager (client) and also to physically set up (rig up / rig down) the cabin's connectivity to the rig site. For the wireline engineer, the operation objectives and tools are similar to D&M except the well-intervention operations are conducted using single-strand or multistrand wire or cable connected to the tool (D&M tools are wireless) that you control through a wireline truck. At one point during one of the wireline operations, we used explosives down the well (I cannot recall the reason since it's been a while, but it was exciting). Last but not least, as the oil well hole is drilled and gets deeper, more mud is required and the mud engineer is responsible for making sure that the new mud to be added is made up to the required specifications. The chemical composition of the mud is designed in order to stabilize the hole. There is a cabin at each rig site for mud testing (lots of geologists hang out there).
It varies, and mainly depends on the segment you are assigned to (you can think of segments as departments within the company). I was part of a segment called Wireline. Wireline is in charge of well logging. Most of the times, we will introduce tools in the well to get information about it and its behavior over time. Things like temperature, pressure, radiation, etc. You will wake up very early to get everything ready to leave with your crew, your logging truck and the tools needed to perform the job. Once there, you're in charge of the operation, if anything goes wrong it is your responsibility. That's why you need to know everything about the whole process (don't worry, they will train you very well). If you have done your preparation, everything should be good. But sometimes, things happens and you need to solve the issue right on the spot. It is a very dynamic job, and it's one of the things I loved the most. It is very unlikely that a welljob is the same as the previous one. Once everything is done, you get back home and prepare your reports. And then get ready for the next one. I know for some segments like D&M, they have to spend the whole month at the location, but then they are free for a month and so on.
No fixed routines. Field Engineers work according to the work demand.
You might be required to work in remote locations in harsh environments. Some operations might not happen as expected and they can extend for long time periods, so be ready for few hours of sleep if required.
You will know different places, even different countries, different nations, cultures. It is very rewardable.