Numerical Simulation of Nitrogen Foam Injection to Control Water Cresting by Bilateral Horizontal Well in Bottom Water Reservoir

Liu Yong-Ge,Pang Zhan-Xi,Liu Hui-Qing

doi:10.2174/1876973x01205010053

Abstract

By numerical simulation, a bilateral horizontal well is placed in a crude oil reservoir with bottom water. The upper branch which is located near the top of the reservoir is for producing and the lower branch which is located near the oil water contract is for nitrogen foam injecting. Packers are used to control the alternation between productions and injections. When water cut of the upper branch reaches a certain value, this branch is shut and nitrogen foam is injected into the lower branch. After two days' soaking, the upper branch is opened to produce again. This process can be repeated for several times along with the reservoir development. The main mechanisms of this development style are analyzed, and different injecting methods including injecting foam in the lower branch (IFLB), injecting foam in the upper branch (IFUB), and injecting nitrogen gas in the lower branch (INLB) are contrasted. The effect of reservoir heterogeneity on the performance of IFLB is also considered. Various stochastic realizations with different shale contents and correlation lengths are established by sequential indicator simulation method. In order to explain the large variations occurring in the realizations with same shale content and correlation length, the definition ‘below well region’ (BWR) is put forward and two groups of models with different BWR are built to simulate the performance of IFLB. As expected, the geological condition of BWR has a great effect on the performance of IFLB. If the shale content of BWR is low, good performance can be obtained with any combination of shale content and correlation length for the remaining region. On the contrary, if shale content and continuity of BWR are high, the performance of IFLB will significantly decrease.

Highlights

For a given rate, horizontal wells require a lower pressure drawdown compared to conventional vertical wells
After soaking, when the upper producing branch is open again, the injected nitrogen foam will provide a great resistance to the invasion water which will lead to a lower water cut and higher oil production rate
Further analysis shows that if shale content and continuity are low for below well region’ (BWR), a good performance can be obtained even for realizations in which shale content and correlation length are both high for rest region (RR)

Summary

INTRODUCTION

Horizontal wells require a lower pressure drawdown compared to conventional vertical wells. Many researchers think that there is a critical rate below which the flat surface of water-oil contact will not deform when using horizontal wells to develop bottom water reservoirs [10, 11]. Barnes [15] in the early 1960s has first suggested that using a viscous water slug can improve the performance of wells in a partially water-invaded reservoir. He pointed out that if the viscosity of injected water was greater than 1.0cp, the flood life could be shortened and the ultimate oil recovery would increase. The effects of reservoir heterogeneity on the performance of blocking agents in bottom water reservoirs are rarely considered

THEORY OF CRESTING CONTROL BY DOUBLE HORIZONTAL WELLS USING NITROGEN FOAM

Reservoir Description and Model Building

Simulation Results and Analysis

Characterization of Heterogeneity and Simulations

CONCLUSIONS

CONFLICT OF INTEREST