Dubai's Fateh Field - Mishrif Reservoir History Of Seawater Injection Project
Authors: Willoughby W.A. , Davies J.A. 
Published: December 2007

A numerical reservoir simulation model was used early in the producing life of a major offshore Dubai reservoir to identify the need for a pressure maintenance - waterflood program. The result was installation of a high volume modular seawater injection plant well before completion of development drilling. Water injection has provided high producing rates, and model projections indicate ultimate producing rates, and model projections indicate ultimate recovery will be significantly improved.

Introduction

Dubai Petroleum Company is the operator for His Highness Sheikh Rashid bin Said al Maktoum of an offshore concession in the Emirate of Dubai, United Arab Emirates. Figure 1 shows the United Arab Emirates offshore area with principal producing fields, including those in Dubai.

The first productive well was drilled in the Dubai offshore area in 1966, and the new field was named Fateh. Development began in 1968, with three productive reservoirs being the target for producing productive reservoirs being the target for producing wells. The main reservoir was the Mishrif formation, of Middle Cretaceous age. The occurrence of the Mishrif in the Dubai area is outlined in Figure 2.

DEPOSITION AND RESERVOIR CHARACTER

The Mishrif formation in the Dubai area was laid down in the Cenomanian Period of the Middle Cretaceous. It is postulated that this formation was laid down in association with the Northwestward migration of a rudist reef complex. The Khatiyah depositional cycle was occurring at the time of the reef development, and the Mishrif is underlain by the Khatiyah in this area. The overlying Mishrif is made up of several different facies with a complex distribution. A study by an independent consultant identified nine different facies units within the formation. These units are shown in Figure 3, along with the occurrence of the various facies units in Well Fateh F-1, which encountered all the units. It can be seen that the lower Mishrif consists mostly of very fine grained limestones, probably from transported and reworked reef material. Coarser reef debris is encountered higher in the section, with shell fragments and entire rudist shells occurring in some wells. The Mishrif forereef was overlain by a very fine-grained Backreef Limestone Facies, with some porous intervals present. porous intervals present. After deposition of the Mishrif interval, a period of erosion followed, which resulted in removal period of erosion followed, which resulted in removal of the entire formation in the central part of the Fateh structure. The upper, coarse debris facies was totally or partially eroded from an area of the reservoir surrounding the area of missing formation and extending downdip approximately halfway to the oil-water contact. Figure 4 shows an outline of the productive Mishrif, with the area of partial and total erosion designated. The total Fateh structure is about 15 Km. (9 + mi) long and 9 Km., (5 + mi) wide. After the period of erosion, subsidence of the area occurred during the Laffan marine advance.

FIRST PRODUCTION

Commercial quantities of oil were discovered in the Mishrif in Well Fateh B-1. A DST of the Mishrif flowed 2556 BOPD in April, 1967. Development began in 1968, with drilling from two platforms, and first production occurred in February, 1970. production occurred in February, 1970.Considerable data gathering was done in the early wells, including PVT analyses of the oil, routine and special analyses of cores, and pressure surveys.