Chapter IV Evaluating Well Performance Evaluate performance production

Chapter IV Evaluating Well Performance

Evaluate performance · production values - bhp - flow rate - GOR - water cut Goal: Understand "Normal"

Two questions: 1. ) What is the producing now? 2. ) What happens when conditions change? (during production) Drive equipment decisions

Oil well Oil Prod - 750 BOPD Water Prod - 150 BWPD Gas Rate - 450 Mcf/d Tubing Pressure = 900 psig Flowing FTP SCF STB

Gas Well Gas Rate = 16. 55 MMscfd Condensate = 695 BCPD Water = 5 BWPD FTP = 2500 psig bcp = 42 mcf

2. 9 2. 5

Productivity Index Model Number 1 st developed for water wells. What will the well produce if pressure changes?

Determine PI with well test. 1. ) shut in the well ← $ $ 2. ) Record the water level 3. ) Produce The well 4) Record the drawdown.

5000 gpd @ 100 ft drawdown 10000 gpd @ 200 ft drawdown PI = 5000 gpd 100 ft = 50 gpd/ft

flowrate q = PI (Drawdown) q = 50 (300) = 15, 000 gpd q=50 (273) = 13650 gpd

Drawdown in feet related to pressure Shut in = bhp Pe Flowing = tubing pressure Pw Freshwater = 0. 433 psi/ft pressure gradient

flow PI = q / (Pe-Pw) Shut-in Flowing 300 ft tubing gauge 129. 9 psi 0. 465 psi/ft – saltwater pressure gradient

q = PI (pe-pw) flowrate number BHP qmax = PI pe FTP

q = 300 BPD Pe = 1800 psi Pw = 1500 psi a) PI =? units b) q =? when pw = 1000 psi

q = PI (pe-pw) Flow pressure difference 300 = PI (1800 -1500) 300 = PI (300) PI = 1 BPD/psi

q = PI (pe-pw) q = 1 (1800 -1000) q = 800 BPD qmax = 1 (1800 -0) = 1800 BPD

Selecting the correct method When can we use the PI method ?

• Dissolved Gas Drive - above bubble point → PI - below → Vogel's method • Water Drive - below rate causes Influx → PI - above rate causing influx → Vogel

• Gas Cap Drive - Prior to breakthrough → PI - After breakthrough → neither