Performance Optimization of CO2 Huff-n-Puff for Multifractured Horizontal Wells in Tight Oil Reservoirs

Mingqiang Hao,Guangming Yu,Yong Tang,Songlin Liao,Xinhui Lei,Jinze Xu

doi:10.1155/2020/8840384

Abstract

In this paper, the sensitivity factors of CO2 huff-n-puff for multifractured horizontal wells (MFHWs) in tight oil reservoirs were investigated through an experimental test and numerical simulation. The pressure-volume-temperature (PVT) experiment and the slim tube experiment are used to understand the interaction mechanism between CO2 and crude oil, and the minimum miscibility pressure (MMP) of the CO2-crude oil system is 17 MPa. The single-well model was firstly established to analyze the sensitivity factors on production performance of MFHWs by using CO2 huff-n-puff. The controlling factors of CO2 huff-n-puff for MFHWs in tight oil reservoirs were divided into three categories (i.e., reservoir parameters, well parameters, and injection-production parameters), and the impact of individual parameter on well performance was discussed in detail. The range of reservoir parameters suitable for CO2 huff-n-puff of MFHWs is obtained. The reservoir permeability is from 0.1 mD to 1 mD, the reservoir thickness changes from 10 m to 30 m, and the reservoir porosity is from 7% to 12%. Based on the reservoir parameters of the target reservoir, the reasonable well and fracture parameters are obtained. The sensitivity intensity was followed by the horizontal well length, fracture conductivity, fracture spacing, and fracture half-length. CO2 injection-production parameters are further optimized, and the sensitivity intensity was followed by the single-cycle cumulative CO2 injection rate, the soaking time, the injection rates, and the production rates. It provides a reference for parameter optimization of CO2 huff-n-puff for MFHWs in tight oil reservoirs.

Highlights

The tight reservoir has gradually become a hot spot of oil and gas exploration and development in recent years
Song and Yang [15] collected core samples from a tight formation with a permeability range of 0.27-0.83 mD to conduct a series of core flooding experiments, and both the near-miscible and miscible CO2 huff-n-puff processes result in higher development efficiency compared to that of water flooding
The aim of this paper is to systematically investigate the influence of the significant parameters on production performance of multifractured horizontal wells (MFHWs) by using CO2 huff-n-puff in tight oil reservoirs

Summary

Introduction

The tight reservoir has gradually become a hot spot of oil and gas exploration and development in recent years. Gas injection through horizontal wells has become one of the most promising enhanced oil recovery (EOR) methods for tight reservoirs [8,9,10]. CO2 injection is one of the most common EOR methods because of its excellent displacing capacity, sweep efficiency, and pressure propagation [11, 12]. CO2 flooding can greatly improve the shortage of water flooding, and it is an effective way to improve oil recovery [13, 14]. Song and Yang [15] collected core samples from a tight formation with a permeability range of 0.27-0.83 mD to conduct a series of core flooding experiments, and both the near-miscible and miscible CO2 huff-n-puff processes result in higher development efficiency compared to that of water flooding.

Objectives

Methods

Results

Conclusion