We would like to share 15 spectacular images that will make you appreciate the beauty of oilfield.
Semi submersible rig
Winter and Pump Jack
Some reservoirs have communication with a water zone (aquifer) underneath. When reservoir pressure drops due to production, the compressed water in an aquifer expands into a reservoir and it helps pressure maintenance. This mechanism is called “water drive”.
Water drive mechanism will be effective if an aquifer contacting reservoir is very large because water compressibility is very low. For example, an anticline structure with extensive water zone (aquifer) will have the most advantage from the use of a water drive mechanism. Conversely, stratigraphic reservoirs or highly-faulted reservoirs will have limited aquifer volume so water drive is insignificant.
Figure 1 – Water Drive Mechanism
Jonathan Lukye who is a supervisor from Sanjel in Estevan, Saskatchewan, Canada shares his cement Excel spreadsheet. He has been working on a Metric Cement Calculator in Excel. In the Excel spreadsheet, it contains; Surface Cement, Intermediate / Production, Liner, Retainer, Plugs, Deviated Hole and Squeeze.
This is the latest version as of 14 September 2016.
Updated features of this version
The Surface, Intermediate and Liner Worksheets are “automatic” where there is no need for a handbook for factors as the sheet calculates them. They also print out the job procedure for that sheet. Continue reading
Some reservoirs have a gas cap, which provides energy from gas expansion to help production from a wellbore; therefore, this is called “gas cap drive”. When oil is being produced, the gas cap expands and pushes oil downwards to a producing well (Figure 1).
Figure 1 – Gas Cap Drive
For this type of drive mechanism, it is imperative to keep gas within a reservoir as long as possible since it is an excellent energy source of the reservoir. Wells which are drilled into a high structure area where the gas cap is located must be closely monitored because this well will have more of a chance to produce gas. Continue reading
Solution gas drive is a mechanism by which dissolved gas in a reservoir will expand and become an energy support to produce reservoir fluid. Solution gas drive has other name, such as dissolved gas drive or depletion drive.
When reservoir pressure is more than the bubble point, no free gas presents in a reservoir and this is called “under saturated reservoir.” At this stage, the drive comes from oil and connate water expansion and the compaction of reservoir pore space. Because compressibility of oil and rock is very low, only a small amount of fluid can be produced and typically the volume is around 1-2% of oil in place.
When reservoir pressure reaches a bubble point, oil becomes saturated and free gas will present in a reservoir. The expansion of gas is a main energy to produce reservoir fluid for the solution gas drive. At the beginning, the produced gas oil ratio will be slightly decline because free gas in a reservoir cannot move until it goes over the critical gas saturation. Then gas will begin to flow into a well. In some cases, where vertical permeability is high, gas may migrate up and become a secondary gas cap, which helps oil production. Continue reading
