Novel Approach to Downhole Separation for Deviated Wells

2019 Artificial Lift Strategies for

Unconventional Wells Workshop Cox Convention Center, Oklahoma City, OK

February 11 - 14, 2019

Novel Approach to Downhole

Separation for Deviated Wells

Jorge Lopez, Eduardo Pereyra, Cem Sarica

University of Tulsa

Outline

Overview of Downhole Separation

Current Challenge: Unconventional horizontal wells

Proposed Approach

Experimental

Model

Preliminary Results

Future Task

Conclusions

2 2019 Artificial Lift Strategies for Unconventional Wells Workshop

Oklahoma City, OK Feb. 11 - 14, 2019

Overview

Downhole Separation

Gravity Separator

Change direction of

fluids to achieve

separation

Rotational Separator

Induce rotation on the

mixture to separate

gas and liquid

Feb. 11 - 14, 2019 3 2019 Artificial Lift Strategies for Unconventional Wells Workshop

Oklahoma City, OK

Bohorquez et al. (2007)

Weingarten

et al. (1997)

Overview…

Downhole Separation

Experimental Studies: General Remarks

No studies on the effect on flow fluctuation

No studies on upstream flow effect

Small amount of studies on inclined

configurations

Specially horizontal and near horizontal

Limited amount of studies on high GOR

cases



Overview…

Downhole Separation

Modeling Studies: General Remarks

No studies on the effect on flow fluctuation

Liquid level in the separator and pump

submergence not considered

Limited studies on separation mechanism

inside the separator



Current Horizontal Unconventional

Well Challenges



Pressure

Pump Location

Guerrero (2016)


Well Challenges

Lateral configuration affects the flow behavior



Vertical Test Section

Toe-down (+1)


Toe-up (-1)


One undulation– sump


Hump

One undulation– hump

Brito (2015)


Well Challenges

Flow fluctuation depending on horizontal

configuration: Conductivity → Holdup




Toe-down (β=+1)

One undulation –

sump (β=1).



Only vertical

section


Well Challenges

Separator can smooth out the flow fluctuation



0

0.1

0.2

0.3

0.4

Series1H D [ft ]

0

0.05

0.1

0.15

0.2

0.25

0 10 20 30 40 50

t [s]

QLo

utQLi

n

q Lo [ft3/s]

q Lin [ft3/s]

Proposed Approach



Proposed Approach…



Separator may experience intermittence

behavior at the inlet

Separator body can be considered as a

liquid accumulator device for the pump




Primary separation (separator inlet) and

secondary separation (separator body)

influence global separation efficiency


Experiments

Experimental campaign

Consider effect of upstream the separator flow

Study liquid level inside the separator

Measure free gas at the liquid rich outlet

Measure gas vented through the casing




Experiments

Experimental facility

Independent variables

Gas flow rate

Liquid flow rate

Inclination angle

Pressure difference

(casing – separator)



Gas

Liquid


Experiments

Measured variables

Global separation

efficiency

Liquid level in the

separator

Liquid holdup at the

liquid outlet



Gas

Liquid 𝐸𝑠 =𝒒𝑔𝑐

𝒒𝑔𝑢

=𝑔𝑎𝑠 𝑟𝑎𝑡𝑒 𝑣𝑒𝑛𝑡𝑒𝑑 𝑎𝑏𝑜𝑣𝑒 𝑠𝑒𝑝𝑎𝑟𝑎𝑡𝑜𝑟(𝑐𝑎𝑠𝑖𝑛𝑔)

𝑔𝑎𝑠 𝑟𝑎𝑡𝑒 𝑏𝑒𝑙𝑜𝑤 𝑠𝑒𝑝𝑎𝑟𝑎𝑡𝑜𝑟(𝑢𝑝𝑠𝑡𝑟𝑒𝑎𝑚)

Coupling of different models

divided into five sections:

1. Separator upstream

2. Annulus casing – shroud

3. Separator inlet

4. Separator body

5. Liquid carryover


Model



Preliminary Experimental Results


Oklahoma City, OK

Dynamic behavior of the separator

𝒒𝑳 = 𝟒𝟑𝟎 𝑩𝑷𝑫

𝒒𝑮 = 𝟖𝟖𝟎 𝑴𝒔𝒄𝒇𝒅

Two initial condition. Full of liquid / Full of gas

Preliminary Experimental Results


Oklahoma City, OK

Dynamic behavior of the separator

𝒒𝑳 = 𝟒𝟑𝟎 𝑩𝑷𝑫

𝒒𝑮 = 𝟖𝟖𝟎 𝑴𝒔𝒄𝒇𝒅

Two initial condition. Full of liquid / Full of gas

Future Tasks

Experimentally

1. Vertical studies. Methodology to evaluate

DHS

2. Inclination angle studies.

3. Effect of horizontal well configurations

4. Effect of pumping system



Future Tasks

Modelling

1. Mathematical guidelines

2. Map operativity envelope

Comprehensive model will be available as a

computational tool.

Python GUI



Conclusions

A novel approach for gravity-driven

downhole separator was presented

The dynamic behavior of the well-separator

system hasn’t been considered before and

we propose to address it (experimentally

and mathematically).

The initial condition of the separator (full of

liquid – full of gas) affect the behavior of the

same.



Acknowledgments

The authors would like to acknowledge The

Tulsa University Horizontal Wells Artificial

Lift Projects (TUHWALP) members for their

support

http://tuhwalp.ens.utulsa.edu/



2019 Artificial Lift Strategies for

Unconventional Wells Workshop Cox Convention Center, Oklahoma City, OK

February 11 - 14, 2019

Novel Approach to Downhole

Separation for Deviated Wells

Jorge Lopez, Eduardo Pereyra, Cem Sarica

University of Tulsa

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Novel Approach to Downhole Separation for Deviated Wells