This is a Special and relatively NEW way to hook-up a well, the main reason for completing a well with this kind of well's completion design is having the Christmas tree not mounted on the top, as a standard wellhead (Vertical Wellhead) we all know, but in one side of the tubing head, sound crazy! well is not; think about the need of having repeatedly work over in that particular well, and think in how the time and cost of that interventions affect your company's costs, think also in one simple reason: the more operations involved in a task, the more risk it'll be involved, due to the potential of errors.
Certainly having the Christmas tree in one side of the tubing head, is the ideal condition for a work-over job done in less time BOP needs only to be installed in the top of the tubing head; and having out the completion by pulling out easy the tubing hanger, in one simple operation without removing flow lines, accessories, and the Christmas tree itself, is not a bad solution; and if we put into a balance all, we can answer properly that the result is a considerable save in time and money.
NOTE: In the studded outlet 2-1/16-5M there is typically a gate valve attached(not shown on the image) or both of them per side the idea is control the annulus space, between the tubing, and the last casing string.
Having said the basic about, is time to make emphasis when, and where apply this Horizontal Wellheads designs.
|WHEN APPLY HORIZONTAL WELLHEADS DESIGNS||WHERE APPLY HORIZONTAL WELLHEADS DESIGNS|
|1) Continuous needs to
work-over the well
2) Continuous Sand in the reservoir making the work-over mandatory, because the continuous block, or flow restriction.
3)Need to change the tubing string, down-hole tools in short time and periods of time.
4)Need to have the well in full production quickly, and at low cost of intervention.
condition in the oil
2)Offshore platforms for the reason mentioned in point(1),and frequent work-over
3)Inland Oil completion, where condition point(1) prevail,and frequent work-over
4)Subsea Wellheads oil Completions,where time involved in work-over for any reason is expensive in anyway.
Table only is a short technical considerations when Horizontal Wellheads systems is convenient to apply but there is some other technical considerations that can't be ignored and they are:
|WHEN IS NOT RECOMMENDED THE USE OF HORIZONTAL
1) Not recommended for working pressures more than 10,000 PSI WP. due to the tendency to generate vibration in the wellhead due to the 90 deg. deflection of the oil flow into the tubing hanger.
2) In areas where there is no space or facility to install the Christmas tree in horizontal position.
3) Initial cost is relatively high due to the special tubing head system used, and the internal components, but can be considered as a long term investment, and the result can be more than revenue.
Some of the basic operation during installation and work-over a well with a horizontal wellhead system are described in some way ahead, making special emphasis in the work-over process showing the way in images an secuencial of the process, and also want you to take notice that I chose a typically section that in pages before were used to explain Vertical Wellheads Completions, so if you have in the field the same one, think on how practical and easy would be the process of transformation your Standard Vertical Wellhead in an Horizontal one.
In a general way we can describe shortly a work-over process in a horizontal wellhead as follow, as the image shows, we need to call Wireline company, and tell them the kind of job to be performed, they after deliver us the cost and terms of their service has to carry on site an intervention oil tool like a Top Adapter or Equivalent (Otis, Baker, etc.) depicted like color olive on top of the actuated gate valve 3-1/8-5M PSI. the purpose of the tool is to connect a device that make possible to plug the tubing hanger, by means of the H-BPV plug inside the tubing hanger thread preparation, so the tool has others facilities not shown, that makes possible the installation of the plug H-BPV. Notice that at this point the upper flange and the pressure gauge are out of this assembly.
Once the procedure of plugging is successful finished, then we need to go to the next steep by removing the tubing bonnet and install the Drilling Spool Adapter 11-5M x 13-5/8-5M with the BOP stack conveniently attached to save time. At this moment the well's intervention is totally assured and the BOP Stack takes the control of the well's pressure. Is important that the previous steep has to be quickly because the tubing hanger is only assured to the tubing heads bowl by the lock down screws ,and in downhole there is pressure. Ahead is an image that shows in some way the situation.Notice that in this particular work-over the BOP is a double ram hydraulically operated, we recommend this models, another detail is the use of a drilling spool adapter, that is for facility only, which means allow a good room for the BOP Stack to be installed, not disturbing the actuated valves, or other accessories in the hook-up
Now is time to remove the tubing hanger and that operation is done by the use of a LANDING SUB oil tool or another oil tool that makes possible to be attached to lifting threads that has the tubing hanger in the top of it, generally used is a EUE8RD lifting thd, but others prefer to use Atlas Bradford(because the strength and seal), Hydrill, or others, so be careful, don't forget to check that your tool to be used in this operation is compatible with, the lifting threads of your tubing hanger.Another special consideration don't forget to:RELEASE THE ALIGNMENT PIN OF THE TUBING HEAD. As you can notice the tubing hanger is a long style, due to the flow outlet in the body.
The preceding image shows the moment when the tubing hanger is being lifted by the rig's cranes tensioning at the same time all the tubing string attached at the bottom of the tubing hanger, so now the crew has work to do, detaching one by one the tubes. In this short explanation as you can see in no way there were pronounced the word Christmas Tree, that means forget the Christmas tree and the accessories attached.
Hope had explained shortly, the advantages of having this kind of hook-up in use, and hope also was understood the more easy way to work wellheads in this way, less time , less cost, more profit.