Multi-Stage Stimulation Technique Boosts Production for Horizontal Wells in Kuwait
Authors: Desai Sameer Feisal , Gazi Nazmul H. , Al-Ajmi Hussain Zuyed , Al-Matar Bader Suilaman , Liu Hai , Abdul Majid Azmin Hartme Bin , Johnston Bryan Bruce 
Published: May 2016

In recent years, horizontal well technology has evolved as the more favorable option in the Middle East over the conventional vertical and deviated wells. The advantages are maximum reservoir contact,higher production rate andbetter access to reserves.

However, horizontal wells completed openhole have very limited scope for effective stimulation, water shutoff and workover treatment. Efficient stimulation of a long openhole section is a very challenging task due to poor and inconsistent acid distribution especially in reservoirs with high permeability streaks. This requires a very effective diversion technique. The efficiency of chemical diverting agents in terms of flow distribution and uniform coverage is limited in such complex wells with long openhole intervals.

This paper illustrates case histories where an innovative technique was used to stimulate horizontal wells, where production had dropped to zero shortly after an openhole completion due to formation damage and incomplete cleanup. The technique combines mechanical isolation and chemical diversion for improved effectiveness of stimulation operations. It uses high performance mechanical openhole packers to segregate the openhole into small intervals based on petrophysical and reservoir evaluation, followed by individual stimulation of each segment with advanced Viscoelastic Diverting Acid as chemical diverters to ensure good zonal coverage across each segment. The result was uniform stimulation of each segment leading to even and maximized inflow from the entire section with one continuous operation.

The first application in the Sabriyah field of the Northern Kuwait oil fields yielded natural production of 10,000 BOPD, which was five times the field average and three times greater than the best well in the field without requiring artificial lift. Significant productivity enhancement was also obtained in another horizontal well in the Minagish field in the West Kuwait region. The oil production was increased from 220 BOPD to 4,788 BOPD. Most recently the technique also successfully brought a dead horizontal well in the Burgan field in the Southern Kuwait area to produce naturally with a rate of 3,827 BOPD. These success stories lead to more applications of this new technology not only in other horizontal wells in Kuwait but also vertical wells in which multiple layers exist.

Introduction

Kuwait Oil Company manages the production and export of oil and gas from more than twelve developed oil fields spread throughout the state of Kuwait. The oil fields are split into three main areas comprising of North fields, West fields, South and East fields (see Fig. 1). The greater Burgan field, located in South and East area, is the world's largest clastic oil field. It covers a surface area of about 320 square miles, and was discovered in 1938. It comprises of a north-south faulted anticline. This field accounts for the largest amount of the oil produced in the country. The four main reservoir units comprising the field area are the Wara, Mauddud, Burgan Third Sand (3S) and Burgan Fourth Sand (4S). There are also other contributing reservoirs namely, Minagish, Marrat & Zubair.