The economic development of thin oil rims associated with large gas caps in multi-stacked reservoirs presents many challenges. In the structurally complex Champion West field, offshore Brunei, innovative well designs together with detailed subsurface studies have unlocked thin oil rims. Earlier development phases comprised deviated and snake wells with multi-zone smart completions. In some areas these wells have resulted in cross-fault depletion of the remaining smaller oil targets. An appraisal strategy was put in place to address the major uncertainties associated with the smaller targets, such as complex fluid distribution and connectivity to existing producers. This strategy comprised drilling pilot holes from development wells, which were evaluated using advanced mud gas logs, downhole pressure measurements and wireline/ logging whilst drilling (LWD) logs to confirm fluid distribution and understand connectivity. This paper discusses one such example, where production data from smart wells has been incorporated with appraisal data to optimise well design, placement and production from a thin depleted oil rim. Multi-rate test information has been used to adjust down-hole inflow control valve (ICV) settings, initially to balance drawdown along the horizontal wells and later to minimise water and gas cap production. Introduction The Champion West field is situated approximately 90 km offshore Brunei in around 50 m water depth. It is composed of approximately 1200m of vertical reservoir sequence with over twenty five separate pressure cells defined to date with complex and variable fluid distributions. The field comprises a series of NNE- SSW-trending elongated fault-blocks [1]. The oil rims discussed in this paper are located in the structurally less complex outer blocks (53–56) at intermediate depth (P5.0-P7.3: 3000–3200 mtvdss). The reservoirs are dipping 20–26 deg and consist of thin sands (1–5m) with limited vertical communication. The recovery from individual sands is typically insufficient for a dedicated horizontal well and combining sands is therefore a must. Large gas caps and weak to moderate aquifers support the oil rims. The vision is to develop Champion West as a "Smart Field" [2]. This includes unmanned platforms, remotely controlled and operated including surface and downhole chokes. Pressure and temperature readings from surface and downhole gauges and fluid flow data are available real-time in the office and feed data driven models that automate production allocation and suggest choke settings to optimize recovery [5]. The smart snake well is selected as the development concept for many oil targets in the field. A snake well meanders in a horizontal sinusoidal pattern through multiple sands providing multiple drainage points in multiple sands. A typical smart snake completion consists of multiple production zones isolated by swell packers. Each zone is equipped with a downhole choke (ICV) and a dual gauge (P,T annulus and tubing). The development of narrow elongated oil rims requires a long horizontal section. Managing torque and drag is key to successful completion. Smart snakes have been successfully applied in Champion West and have shown several advantages [4]. A brief summary of the field development history is given in the next section. For the development of the smaller oil rims, low cost appraisal sidetracks are drilled from the development wells. This paper discusses one example (CW-G), where the smart snake well concept with appraisal sidetrack is used to develop narrow elongated oil rims.
A new seismic and quantitative reinterpretation was carried out for a brownfield in Western Desert, Egypt to improve depth predictability, de-risk appraisal well locations and to better understand producer-injector connectivity. The study field is located in the Western Desert, Onshore Egypt and comprises of Upper Cretaceous tidal channel systems across four key reservoir levels where sand thicknesses range from 2 to 15 m. The field was discovered in 1993 but development drilling only commenced in 2008. The last integrated field study was performed in 2012. The analysis of wells drilled post-2012 indicated that there is a considerable depth difference along the flanks of the structure between seismic predicted depths and actual well tops (>50 m). The fault interpretation also required a re-look so as to reduce the lateral uncertainty of the main boundary fault and explain the lack of injection response in some areas of the field. This necessitated an update of seismic interpretation, static and dynamic models. A new interpretation could help identify attic volume upsides and help mature new appraisal and producer-injector locations. Further work was also proposed to test the feasibility of using seismic inversion for facies discrimination. The available Pre-Stack Depth Migration (PreSDM) data was re-interpreted as part of the project. The fault interpretations were quality checked using Semblance/Dip maps, sand box models and wherever possible, were tied to the fault cuts seen in previously drilled wells. The time horizon correlation and seismic polarity were verified and were also cross-checked with the P-Impedance volume before being used in the static modelling workflow. The PreSDM Interval velocity model was used for depth conversion, where an anisotropy correction was applied to tie the wells. Vok and Polynomial methods were also applied, which in turn were used to derive depth uncertainty estimates. The update in the main bounding fault interpretation generated new appraisal locations in the deeper levels. The new interpretation was tested against the results from the latest drilling campaign in the field, and nine out of ten wells were within the one standard deviation uncertainty range. Simultaneous inversion of the seismic data was also carried out as part of the project using the acoustic, shear and density data from 6 wells over the field. The inverted P-Impedance and S-Impedance were converted to Net to Gross (NtG), and were checked against the remaining 24 wells, which helped in validating the property cubes. Forward wedge modelling suggested that individual sands of less than 15 m thickness would not be resolved from seismic due to seismic bandwidth limitations. Still, a review of inversion data together with geological insights and dynamic data helped to identify the high NtG areas across the reservoirs. The integrated interpretation of inverted volumes with well and production data resulted in new insights into the field and helped to mature new appraisal and development well locations.
The current phase of the Champion West Field Development is one of BSP's most challenging project to date for drilling and completion reasons. The Champion West field was discovered in 1975, but its rich oil and gas reserves lay dormant for 30 years, locked beneath the seabed in a complex web of reservoirs deemed too expensive to develop using conventional development plans. It is a large undeveloped oil and gas resource in Brunei. Hydrocarbons are found in shallow marine reservoirs-these vertically stacked, structurally dipping reservoirs are complex and contain various fluid fills ranging from gas only to gas with oil rims to oil.
This article describes both the implementation of a structured review process of field performance for managing an existing waterflood in North Kuwait and summarizes how this process can lead to enhanced oil recovery. The aim of the review process, applied to the Upper Burgan and Zubair in the Raudhatain field, is to enhance understanding of the reservoir performance, through the movement of the injected water, and the impact on produced oil based on increasing sweep efficiency. This methodology will identify unswept oil and opportunities to mobilize it to be pushed towards the production wells by enhancing the effectiveness of the injected water to maximize recovery. In this work, we describe a systematic approach, callled WRFM, which is in summary an integrated geology, reservoir engineering and field management review process of all available data in a field. This process has been developed with the purpose of identifying opportunities at both well and pattern level to enhance water injection effectiveness in specific layers of a multi-stacked reservoir field.
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