Abstract

This paper demonstrates the benefits to be gained from performance analysis of gas-lifted vertical and horizontal wells in Hassi R'mel oil rim, where significant incremental oil production rate can be achieved as water-cut increases and reservoir pressure declines by a comprehensive approach to the problem of gas-lift production optimization.

An artificial-lift method in which gas is injected into the production tubing to reduce the hydrostatic pressure of the fluid column. The resulting reduction in bottomhole pressure allows the reservoir liquids to enter the wellbore at a higher flow rate. The injection gas is typically conveyed down the tubing-casing annulus and enters the production train through a gas-lift valves. The gas-lift valve position, operating pressures and gas injection rate are determined to ensure maximum well productivity by specific well conditions.

The gas lift software used provides the ability to accurately design and maintain efficiency of gas lift production systems, by combining data acquisition and automation with proven gas lift engineering techniques. Additionally, root causes of failures can be systematically identified using sensitivity analysis tools. Combined well and flowline performance was analyzed with a multiphase network hydraulic simulator that determined maximum transport capacity of the well and flowline system while ensuring that reservoir simulator, wellbore, and facilities constraints were met.

Introduction

The Hassi R'mel field is located approximately 500 kilometers South of Algiers in the Northern Grand Erg occidental of the Algerian Sahara. The Hassi R'mel field was discovered in November 1956 by the drilling of well HR-1. Early evaluations of the discovery revealed it to be one of the largest gas fields in the world which has an oil rim existing primarily along the Eastern and Southern margins of the field.

The reservoir of Hassi R'mel oil rim, contains thin oil columns of 30 feet average overlain by a large gas cap with bottom aquifer support.

Water and gas coning are serious problems in many oil field applications, where the production of water and gas from a thin oil reservoir is a common occurrence, which increases the cost of producing operations, and reduces the efficiency of the depletion mechanism and the overall recovery.

In water-coning systems, the viscous forces are caused by pressure drawdown near the wellbore which results as a consequence of fluid production, and the gravitational forces arise from the density difference between two fluids which tend to counterbalance the viscous forces, if the viscous forces exceed the gravitational forces than a cone is formed and grows up toward the perforated interval until water breaks into the wellbore.

Many horizontal wells have been drilled in addition to vertical wells in Hassi R'mel oil rim based on the simulation study and economic analysis, which was conducted to investigate the optimum number of vertical and horizontal wells (enhance reservoir contact and thereby enhance well productivity) to be drilled in Hassi R'mel oil rim.

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