Research on the Inflow Performance of the Plunger Lift in the Shale Gas Horizontal Well

Changqing Ye,Lu Jiang,Daogang Cai,Hanbing Tang,Nanxing Xie,Qingrong Wang,Jianyi Liu,Sivasankaran Sivanandam

doi:10.1155/2022/4401128

Abstract

Shale gas wells in the Changning block of Weiyuan, Sichuan, China, experience water production problems throughout their life cycles. In actual field production, plunger lift is typically used to discharge liquid from a shale gas well. However, it is difficult to test the formation inflow performance relationship curve (IPR) of a plunger lift well. Hence, data on the formulation and optimization of plunger lift well systems are lacking. Based on actual measured data related to casing pressure changes at the wellhead and the gas-liquid distribution characteristics in a wellbore during the shut-in phase, this paper establishes a method for calculating the formation IPR curve of a shale gas plunger lift well by calculating changes in wellbore gas volume continuously. This method has a fast calculation speed. The gas-water interface distribution can be obtained in 3–5 iterations, and the inflow dynamic curve can be calculated in less than 5 seconds. This method tested the IPR curves of gas wells in the Changning block. The IPR curves of plunger lift wells showed concave characteristics contrary to the conventional upward convex curves. This is because the bottom hole flowing pressure changes caused variations in the water saturation of the near-wellbore zone. Consequently, the productivity equation of the plunger lift well is established by introducing the variation coefficient of water saturation expressed by bottom hole flow pressure. This equation fits with the measured IPR curve with an average R2 of approximately 0.9989.

Highlights

Shale gas reservoirs have low porosity and permeability characteristics [1]
In the early stage of gas production, the formation energy is sufficient for bringing out the water from the gas well
To accurately obtain the formation IPR curve of the plunger lift well, this paper proposes a method to determine the formation inflow performance based on the wellhead casing pressure data tested during the shut-in phase of the plunger lift. is method uses data related to changes induced in the wellhead casing pressure during the shut-in phase to calculate the gas volume flowing into the casing from the formation, thereby obtaining the formation IPR curve

Summary

Introduction

Shale gas reservoirs have low porosity and permeability characteristics [1]. Because of this, they often use large-scale hydraulic fracturing for gas production [2, 3]. To accurately obtain the formation IPR curve of the plunger lift well, this paper proposes a method to determine the formation inflow performance based on the wellhead casing pressure data tested during the shut-in phase of the plunger lift. Is section establishes a test method for deriving the formation IPR curve of a plunger lift well using wellhead tubing and casing pressure data obtained for the shut-in stage and wellbore gas-liquid interface distribution. Since the wellbore gas flows slowly during the shut-in stage, the pressure on the surface of the liquid in the tubing and casing can be calculated using the static pressure of the gas column as follows [32]: pctwu pc exp􏼠0.03148cgHctg􏼡 TctZct (5). The calculation can be completed in 2–4 iterations

Basic Situation of Typical Wells

Data Smoothing

Measuring the Formation Inflow Performance

Productivity Equation considering the Change in

Findings

A Typical Well Productivity Curve