The need to develop new tools that allow reservoir engineers to optimize reservoir performance is becoming more demanding by the day. One of the most challenging and influential problems facing reservoir engineers is well placement optimization.
The North Kuwait field (NKF) consists of six fields containing four naturally fractured carbonate formations. The reservoirs are composed of relatively tight limestone and dolomite embedded with anhydrate and shale. The fields are divided into isolated compartments based on fault zones and supported by a combination of different fluid compositions, initial pressures, and estimated free-water levels. Due to natural complexity, tightness, and high drilling costs of wells in the NKF, it is very important to identify the sweet spots and the optimum well locations.
This paper presents two intelligent methods that use dynamic numerical simulation model results and static reservoir properties to identify zones with a high-production potential: reservoir opportunity index (ROI) and simulation opportunity index (SOI). The Petrel* E&P software platform was chosen as the integrated platform to implement the workflow. The fit-for-purpose time dependent 2D maps generated by the Petrel platform facilitated the decision-making process used for locating new wells in the dominant flow system and provided immense support for field-development plans.
The difference between the two methods is insignificant because of reservoir tightness, limited interference, and natural uncertainty on compartmentalization. At this stage, pressure is not a key parameter. As a result, unlike brown fields, less weight was given to simulated pressure, and SOI was used to select the well locations.
The results of this study show that implementing these workflows and obtaining the resulting maps significantly improve the selection process to identify the most productive areas and layers in a field. Also, the optimum numbers of wells using this method obtained in less time and with fewer resources are compared with results using traditional industry approaches.
North Kuwait had discovered several deep reservoirs during 1960s which were not considered for development production till 2010 because of higher priority given to the major reservoirs such as Mauddud and Burgan. Zubair and Ratawi are two such new reservoirs, taken up for fast track development since last 2 years.
In order to achieve the production target for the asset, ZU/RT need to be brought to production. A complete evaluation of all geological/ Geophysical data was done for all penetration through ZU/RT. All testing results available during the exploratory wells were comprehensively gathered and evaluated. Based on the data, fast track well release, drilling & completion were initiated. The objective was to gain production as well as data to reduce the uncertainty for further development and reservoir modeling work. The initial results indicated tremendous challenges in terms of fluid regime as well as reservoir rock properties.
The production, at the beginning of the project, was zero, which has now been increased to about 20 MBOPD within a year. Integrated team work and calculated risks helped to achieve this milestone.
The paper aims to share the challenges and the lessons learnt during the production delivery from the new reservoirs in North Kuwait.
Geological Background/ Setting
Sabiriyah Zubair is a minor reservoir of clastic type, which was on low priority for development/ production since discovered druing 60s.. This is a relatively small reservoir in terms of size and potential, as compared to other major reservoirs in Sabiriyah field viz. Mauddud & Burgans. However, the accomplished intial tests at two wells (SA-00271 and SA-0278) indicate that the reservoir has mobile oil and can participate to contribute to NK overall production. Currently 7 wells are flowing to Gathering centre at total rate of about 10 MBOPD.