Abstract

In recent years, M oilfield has entered into high water cut stage. Two main problems are imposed in the process of development including sharp water cut rising rate and rapid oil production decline. These problems are difficult to solve, which may bring other problems. In order to slow down production decline rate and control the rising rate of water cut, it is necessary to control water injection rate. However, oil production rate can be affected if water injection rate is too low to provide enough water volume for maintaining reservoir pressure. A method to calculate reasonable injection–production ratio and predict water cut is provided in this paper. Its main mechanism is to resolve above contradictions by calculating reasonable water injection rate. Firstly, an equation to calculate reasonable injection–production ratio is deduced by material balance equation. It considers several parameters including rate of pressure recovery, water cut and other production indexes. Secondly, reasonable oil production rates and water cut of future 10 years are predicted. Oil production is predicted by the law of production decline, and water cut is predicted by regression equation of water drive characteristic curve. Lastly, reasonable water injection rates of next 10 years are calculated through predicted injection–production ratios and liquid production rates. Taking M oilfield as an example, this paper presents a method to determine reasonable water injection rate of multilayer sandstone water drive reservoir.

Highlights

  • For the development of multilayer sandstone heterogeneous water drive reservoirs, because of the inhomogeneous advance of injected water in vertical and horizontal directions, dominant channels of water flow in reservoir are formed (Li 2003; Wagn et al 2016; Sommerauer and Zerbst 2007)

  • Oil production is predicted by the law of production decline, and water cut is predicted by regression equation of water drive characteristic curve

  • Luo investigated the quantitative relationship among injection–production ratio, reservoir pressure, liquid production and water cut through material balance equation and water drive characteristic curve (Luo and Xu 1999; Wang 2013; Palsson et al 2003; Olu et al 2014)

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Summary

Introduction

For the development of multilayer sandstone heterogeneous water drive reservoirs, because of the inhomogeneous advance of injected water in vertical and horizontal directions, dominant channels of water flow in reservoir are formed (Li 2003; Wagn et al 2016; Sommerauer and Zerbst 2007). Luo investigated the quantitative relationship among injection–production ratio, reservoir pressure, liquid production and water cut through material balance equation and water drive characteristic curve (Luo and Xu 1999; Wang 2013; Palsson et al 2003; Olu et al 2014). Cui calculated water influx rate of edge water reservoir by material balance equation. Based on water influx rate, relational formula between formational pressure recovery rate and injection–production ratio is deduced. Based on material balance equation and water drive characteristic curve, a lot of research has been performed on the law of oil field water injection in recent years (Bashiri and Kasiri 2011; Chambers et al 1980; Dong et al 1999). Reasonable development indexes of M oilfield are predicted. Its main objective is to control these indexes at a proper range, which could handle with the contradiction between reservoir pressure and water cut for multilayer sandstone water drive reservoir

Geological conditions
Development history
Basic wells
The method to calculate oil production rate
The method to predict water cut
Predicted oil production
Fwo qw qo
The method to calculate reasonable water injection rate
Findings
Conclusions

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