How to calculate Well Bore pressure drop?

[ibtisam01]

Hi every one,

I am a bit new to reservoir simulation. I am running Horizontal well simulation in Eclipse 100. I have got few questions and these are creating difficulties for me. I have run the simulation for 1500 days. Now please please give me answers of these:

1. How I can calculate pressure drop along the well bore length
2. How I can calculate reservoir draw down i.e. difference b/w average reservoir pressure and the pressure and the producing end(Heel) of the well bore.

Are there any keywords used in Eclipse 100 for such calculations ?I will be very thankful to all. Kindly help me.

[DAH7542]

Dear ibtisam01,

1. How can I calculate pressure drop along the well bore length
- There are plenty of papers on this. Start by reading Joshi's book on Horizontal Wells, from p. 398. Then take a look of these papers: SPE 19824, SPE 21124, SPE 36608, SPE 48937. Modelling the pressure drop through the horizontal section incorporates more information to the simulation model, however this issue can be ignored under some specific conditions such as: non-turbulent flow (flow rates less than 10,000 bpd according to the literature) and low viscosity fluid flows, take a look at SPE 24941. After this background, you'll be able to built your own spreadsheet of dP as function of horizontal well length (L).

2. How I can calculate reservoir draw down i.e. difference b/w average reservoir pressure and the pressure and the producing end(Heel) of the well bore.
- This can be done by using User Defined Quantities (UDQ) in E100. With this functionality of E100 any variable can be defined and reported as a part of the SUMMARY section. Simply use UDQ to defined drawdown as the wellblock pressure minus WBHP. You can then plot drawdown as a function of horizontal well length (L) to observe the pressure distribution within the horizontal section.

[ibtisam01]

Thanks for the valuable info. Well I have tried starting reading papers, but i have very less time available to complete my project. Now I ask you one question regarding calculation of pressure drop along the well bore length. I have 2 strategies coming in my mind.

1. If I minus WBHP from the connection pressure (at the toe of horizontal section) , will this be the pressure drop along the length of horizontal section?

2. If I minus connection pressure (at the heel of horizontal section) from the connection pressure (at the toe of horizontal section) , will this be the pressure drop along the length of horizontal section?

Kindly reply. Thanks in advance.

Dear ibtisam01,

1. How can I calculate pressure drop along the well bore length
- There are plenty of papers on this. Start by reading Joshi's book on Horizontal Wells, from p. 398. Then take a look of these papers: SPE 19824, SPE 21124, SPE 36608, SPE 48937. Modelling the pressure drop through the horizontal section incorporates more information to the simulation model, however this issue can be ignored under some specific conditions such as: non-turbulent flow (flow rates less than 10,000 bpd according to the literature) and low viscosity fluid flows, take a look at SPE 24941. After this background, you'll be able to built your own spreadsheet of dP as function of horizontal well length (L).

2. How I can calculate reservoir draw down i.e. difference b/w average reservoir pressure and the pressure and the producing end(Heel) of the well bore.
- This can be done by using User Defined Quantities (UDQ) in E100. With this functionality of E100 any variable can be defined and reported as a part of the SUMMARY section. Simply use UDQ to defined drawdown as the wellblock pressure minus WBHP. You can then plot drawdown as a function of horizontal well length (L) to observe the pressure distribution within the horizontal section.

[DAH7542]

Dear ibtisam01,

The wellbore pressure drop inside the horizontal well section is a concept related only with the frictional and fluid acceleration pressure drop inside the well, I mean it is not a reservoir-related issue but a wellbore-issue. It depends on the Length of horizontal lateral (liner), Friction Factor, fluid density, flow rate, internal diameter, relative pipe roughness and some other wellbore parameters.

In summary, the reservoir simulators such as E100 cannot solve for this by its own, this information must be provided as an input to the simulator in table formats. These tables of wellbre pressure drop vs depth (horizontal well section) can be built in a simple excel file by using any available model for it (SPE papers I recommended) or by using any commercial software for those purposes (Wellflo or any other).

My answer to your previous question: If in your run you didn't specified the wellbore pressure drop along the horizontal length by means of, for instance the Wellbore Friction Option in ECLIPSE, neither strategy (1 or 2) will give you the pressure drop along the well bore length.

[ibtisam01]

Dear DAH7542,

I have applied well bore Friction option in eclipse and it is running.

I have used Keyword 'Friction' in RUNSPEC section and 'WFRICTION' in schedule section. but I dont understand where to bring values of the following:

1. Friction Factor (I dont know from where I can get this)
2. Fluid density, (Surface Oil, water and gas densities are defined in the keyword DENSITY in PROPS)
3. Flow rate (It is defined as a control mode LRAT IN item 3 of WCONPROD)
4. Internal diameter, (I think it is defined in WELSPECS item 9)
5. Relative pipe roughness (I think it is defined in Record 1 of WFRICTION ITEM 3)

And also is this the correct formula to calculate pressure drop along the horizontal well length?

Pressure drop = 2*f*(L/D)*density*Velocity(Square) ?

Kindly do favor for me and let me know how to easily solve pressure drop along the horizontal section.

Bundle of thanks

Read more:

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Dear ibtisam01,

The wellbore pressure drop inside the horizontal well section is a concept related only with the frictional and fluid acceleration pressure drop inside the well, I mean it is not a reservoir-related issue but a wellbore-issue. It depends on the Length of horizontal lateral (liner), Friction Factor, fluid density, flow rate, internal diameter, relative pipe roughness and some other wellbore parameters.

In summary, the reservoir simulators such as E100 cannot solve for this by its own, this information must be provided as an input to the simulator in table formats. These tables of wellbre pressure drop vs depth (horizontal well section) can be built in a simple excel file by using any available model for it (SPE papers I recommended) or by using any commercial software for those purposes (Wellflo or any other).

My answer to your previous question: If in your run you didn't specified the wellbore pressure drop along the horizontal length by means of, for instance the Wellbore Friction Option in ECLIPSE, neither strategy (1 or 2) will give you the pressure drop along the well bore length.

[DAH7542]

ibtisam01,

1. Friction factor: can be calculated from eq. 10-10 and 10-11 in p. 392 JOSHI Horizontal Well Technology
5. Relative pipe roughness : see fig. 10-4 in JOSHI Horizontal Well Technology

If you carefully read Joshi's book from p. 398 you'll get this more clear, take the time to do it. Good luck.

[ibtisam01]

Well , I have tried to absorb the concept , but i dont know how I can incorporate this in simulation model, may be because lack of experiecne in simulation. Feeling lost.........

ibtisam01,

1. Friction factor: can be calculated from eq. 10-10 and 10-11 in p. 392 JOSHI Horizontal Well Technology
5. Relative pipe roughness : see fig. 10-4 in JOSHI Horizontal Well Technology

If you carefully read Joshi's book from p. 398 you'll get this more clear, take the time to do it. Good luck.