This document discusses liquid loading issues in two gas wells, Well Y and Well Z. It provides reservoir and completion parameters for each well, and calculates the critical gas velocity and flow rate for each using established models. Both wells are experiencing liquid loading as their gas rates are below the critical values. It is proposed to install sand screens and re-complete the wells with selective reverse circulation pumps to address the liquid loading by keeping production below the perforations and allowing gas to flow through the annulus. The total capital costs and payback periods for implementing this solution are estimated for each well.

1. SOLVIER
CASE STUDY SOLUTION
submitted by :-
Jash PATEL
Vishal Vyas

2.  Sand Production in Well
 Liquid Loading
 What is liquid loading?
 Liquid loading occurs when the gas velocity is insufficient to carry the produced liquid to surface facilities.

3.  Liquid loading cause the slug flow which cease the production of gas.
 Difficult to identify.
 Identification of Liquid loading in Gas wells
 Turner, Hubbard and Dukler & Coleman find the liquid transport model in vertical gas
flow.
 Model is known as “minimum critical flow rate” or “critical velocity”-
 If Vg(Gas Velocity) < (Vgc) Critical Velocity , Cause liquid loading.

4. where,
Vgc: Critical gas velocity (ft/s)
K Constant : 1.92 ( Turner ),1.59 (Coleman)
σ :Surface tension liquid to gas ( dyne/cm)
ρg: Density of gas ( lb/ft3)
ρl: Density of liquid ( lb/ft3)
Qgc: Critical gas rate (MMscf/d)
Vgc: Critical gas velocity (ft/S)
A: Cross sectional area (ft2)
T: Temperature (F)
P: Pressure (psi)
Z: Compressibility factor
𝑄𝑔𝑐 =
3.06 ∗ 𝑃 ∗ 𝐴 ∗ 𝑉𝑔𝑐
𝑇 + 460 ∗ 𝑧

5. For Well Y
Reservoir Parameters Completion Parameters
Perf Depth (m) 858-860.5 Tubing Size * 2 7/8” or 2
Reservoir Pr(KSc): 79 Casing Size 5 ½”
FBHP (KSc): 77 Production Casing Shoe
927
Production Details:
Last gas flow rate recorded (m3
/d):15850
Last liquid rate recorded (m3
/d): 9
Water cut (%): 100
Expected THP(KSc): 25
Given Data

6.  Now calculating the critical velocity by assuming the following data:
Density of gas (ρg): 0.0401 lb/ft3
Compressibility factor Z: 0.85
Surface Tension: 60 dyne/cm
Reservoir temp.: 114.8 F
Density of water(ρL): 67 lb/ft3
Calculating the critical velocity
Vgc = 63.2271 ft/s
Qgc = 211701.86 m3/d
Here Qgc > Qg
Note: assumed data is same for both the Well Y & Z.

7. For Well Z
Reservoir Parameters Completion Parameters
Perf Depth (m): 790-795 Tubing Size: 2 7/8” or 2 3/8”
Reservoir Pr (KSc): 76 Production Casing size: 5 ½”
Flowing Bottom Hole Pressure Production casing shoe (m): 798
(KSc): 71
Production Details
Last gas flow rate recorded
(m3/d): 16000
Last liquid rate recorded (m3
/d): 7.604
Water cut (%): 100
Expected THP (KSc): 25

8. From the values we have we got the value of critical velocity & critical flow rate as following:
Vgc = 63.2271 ft/s
Qgc = 195205.61 m3/d
Here Qgc>Qgz

9. In Both Well, Liquid Loading.
Using SRP, We keep it Below Perforation.
Gas Comes out from annulus.

10.  Economic Analysis
• CAPEX
• SRP :- Rs 30 lakhs
• Tubing cost :-
Y :- 800 x 900= Rs 7.2 lakhs
Z :- 800 x 796= Rs 6.36lakhs
• Workover cost :-
Rig Operating Day Rate (RODR) :- 22.5 lakhs
Inter location move Charges (ILMC ):- 6.5 lakhs
Rig Transportation Cost :- 5.1 lakhs
GST :- +12%
Total :- 38.192 lakhs
• Sand screen :- 1 lakhs

11.  Total CAPEX
Y :- Rs 82.752 lakhs
Z :- Rs 84.75 lakhs (Assume Separator Cost 2 lakhs)
 Revenue
Y :- Rs 2.92 lakhs / Day
Z :- Rs 2.95 lakhs / Day
 Payback period
Y :- 28.3 Days
Z :- 29 Days