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Collaborating Authors
Abstract The successful drilling of horizontal wells is extremely difficult, mainly due to lithological discontinuities and seismic uncertainties. To overcome such challenge, Well Placement technique is used to interactively position the well based on geological and seismic criteria together with LWD measurements. While covering drilling, geology and geophysics, most Well Placement approaches rarely consider reservoir engineering aspects. This paper presents an innovative methodology that integrates reservoir engineering into Well Placement workflow to improve well's productivity performance. The applied method is based on advanced 3D modelling, where by means of numerical reservoir simulations, productivity predictions are performed not only on the planned well but also at the executed trajectory. To increase prediction accuracy, a refined gridding with variable cell size technique is applied to enhance pressure and saturation sensitivity. The level of precision is improved by using LWD measurements, such as most precise formation pressure, permeability near wellbore and remote boundary mapper technology that provides a detailed reservoir structure based on formation resistivity contrast. This methodology was employed in a real case study of a horizontal well drilled in an offshore sandstone field in Brazil. As common occurrence in Well Placement operations, the executed trajectory had significant geometrical differences compared to the planned one. For both planned and executed wells, a detailed reservoir model was created using the inputs of LWD measurements. Numerical simulations were then applied to both wells in order to evaluate the impacts caused by the trajectory variations, showing the expected productivity results versus the actual ones obtained at the drilling operation. The results demonstrated indeed a major productivity impact in all reservoir fluids when a well trajectory is subjected to geometrical changes. However, only through the use of this integrated approach could such impact be quantified, since the traditional Well Placement methodology cannot determine the effects on the productivity response based only on the geological and petrophysical aspects. The work delivers a novel ability to construct optimal horizontal wells not only by including conventional Well Placement technique, using geological and geophysical criteria, but also by introducing into the workflow an advanced numerical simulation approach. Such integration allows the operator to predict the impacts on the productivity as the trajectory is being changed, and the actual reservoir geometry and its properties are determined by LWD measurements.
This paper was prepared for presentation at the 8th Abu Dhabi International Petroleum Exhibition and Conference held in Abu Dhabi, U.A.E., 11-14 October 1998.
- Asia > Middle East > UAE > Abu Dhabi Emirate > Abu Dhabi (0.44)
- Asia > Middle East > Oman > Ad Dhahirah Governorate (0.44)
- Asia > Middle East > Oman > Ad Dhahirah Governorate > Fahud Salt Basin > Yibal Field > Yibal Khuff Formation (0.99)
- Asia > Middle East > Oman > Ad Dhahirah Governorate > Fahud Salt Basin > Yibal Field > Sudair Formation (0.99)
- Asia > Middle East > Oman > Thamama Group > Shu'aiba Formation (0.98)
Innovative Integration of Seismic and Reservoir Simulation Modeling with Drilling and LWD Measurements to Manage Development Risk in Complex Channel Reservoirs—Opening Opportunities to Redevelop Mature Field in Bohai Bay, China
Bie, Xuwei (CNOOC Tianjin (CCLT)) | Yang, Qinghong (CNOOC Tianjin (CCLT)) | Liao, Xinwu (CNOOC Tianjin (CCLT)) | Nie, Chaomin (CNOOC Tianjin (CCLT)) | Hu, Yong (CNOOC Tianjin (CCLT)) | Thanh, Tran (Chevron) | Hao, Cheng (Chevron) | Lin, Wen (Chevron) | Halomoan, Parlindungan Monris (Schlumberger) | Xu, Chong Hui (Schlumberger)
Abstract The Qin Huang Dao 32-6 (QHD 32-6) mature oil field is located in Bohai Bay, China. The field has cumulative oil production of 135 million barrels, produced by 174 production and 28 injector wells. A redevelopment project with four new platforms and 101 wells—88 horizontal wells and 13 directional high-angle wells—in five major reservoirs was initiated in late 2010 with the objective to recover an additional 98 million barrels of original oil in place (OOIP) by Year 2035. The redevelopment and exploitation of these targets present complex operational challenges. Uncertainties that may have significant impact on prospect definition and field redevelopment execution are associated with the complex subsurface environment of soft, unconsolidated, fluvial channel sand reservoirs, with the maturity of a heavy oil field with uncertain natural aquifer or injected water sweep, and with well surveys and well depth control. Not only must a planned horizontal well be optimally placed within the complex channel sand facies, which dramatically changes vertically and laterally across the field, but because of the high viscosity and low gravity of the heavy oil, which has a much lower mobility than the water, the horizontal well must be placed in the good-quality reservoir zone underlying the siltstone zone while also keeping the well away from the unknown current fluid contact. To reduce the uncertainties and ensure the optimal placement of the well in the best position to drain the remaining hydrocarbons, we have implemented the combined integration of multimethod-processed seismic data and reservoir simulation models with a rotary steerable drilling system and logging-while-drilling (LWD) azimuthal deep directional electromagnetic-based measurements. The seismic data and reservoir simulations highlight both structural and sedimentary features in the macro scale. These simulations are used as the reference for reservoir target selection, well planning, and well execution. The azimuthal LWD data highlight the reservoir at the micro scale, with the ability to map the lithologic boundaries and fluid contacts in distance. The rotary steerable drilling system provides accurate well control while maneuvering in soft and unconsolidated sands. Data from both logging and drilling systems are used during well execution in addition to the seismic and reservoir simulation data. On the basis of multiple well field studies discussed in this paper, the team has observed that the integrated application has helped to Identify optimal reservoir target location selection and well planning Identify geobodies of the complex channel sand facies and their interfaces with accuracy Identify the current fluid contacts Identify the best position to drain the hydrocarbons Reduce overall subsurface-associated risks. Finally, the authors conclude that by facilitating seismic and reservoir simulation of the macro system in combination with the accuracy and efficiency of drilling and LWD measurements in the micro system with respect to geology and reservoir engineering, the redevelopment of the mature field can be optimally planned and executed with the eminent potential for further improvement of the field recovery factor, yielding a significant economic value.
- Asia > Kazakhstan > Aktobe Oblast > Precaspian Basin > North Block (0.99)
- Asia > China > South China Sea > Pearl River Mouth Basin > Huizhou Field (0.99)
- Asia > China > East China Sea > Bohai Basin > Jiyang Basin > Guantao Formation (0.99)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Well Drilling > Drilling Measurement, Data Acquisition and Automation > Logging while drilling (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
With the advent of rotary steerable systems, successful drilling of horizontal wells became a reality in the oilfield. Even though the costs are much higher than for a vertical well, the production factor can be enhanced multiple times, making it very attractive. However, the drilling of horizontal wells is extremely difficult, mainly due to lateral lithological discontinuities of the reservoirs and seismic uncertainties. To overcome such challenge, Well Placement technique is used to interactively position the well based on geological and seismic criteria together with LWD measurements. While covering drilling, geology and geophysics, most Well Placement approaches rarely consider reservoir engineering aspects. Therefore the project objectives were to evaluate the impacts in the productivity generated by the geometrical changes in the trajectory through numerical reservoir simulation. The research work was then divided into two parts. The first one was the creation of a representative 3D synthetic reservoir model where numerical simulations were applied for each trajectory design. A detailed sensitivity analysis was made by comparing the results among the different trajectory cases in order to identify the relationship between well positioning and its productivity response. The second part consisted of a real geosteering case study. Around both planned and executed wellbores, it was created a detailed reservoir model enhanced by LWD inputs. To increase prediction accuracy, a refined gridding with variable cell size technique was applied to enhance pressure and saturation sensitivity. The level of precision was improved by using LWD measurements, such as the most precise formation pressure, the permeability near wellbore and the remote boundary mapper technology that provided a detailed reservoir structure based on formation resistivity contrast. Afterwards, reservoir simulations were performed in order to evaluate the impacts caused by the trajectory variations, demonstrating the expected productivity results versus the actual ones. The work delivers a novel ability to construct optimal horizontal wells not only by including conventional Well Placement technique, using geological and geophysical criteria, but also by adding into the workflow an advanced numerical simulation approach. Such integration allows the operator to predict the impacts on the productivity as the trajectory is being changed, and the actual reservoir geometry and its properties are determined by LWD measurements. It also reinforces that predictions related to reservoir productivity should not only be performed on planning stage, but most importantly during or right after well execution using relevant inputs, such as the actual well path, LWD logs, and formation pressure measurements, which all combined provides an enhanced reservoir model, and so a more accurate forecast analysis.
SPE Member Abstract The Baram ‘South’ area is a largely undeveloped fault block in the Baram Field which contains some 154 MMstb of oil. Due to the elongated nature of the fault block, the moderately high in-situ oil viscosity of 6 cP. and the strong water drive, a horizontal well development has been identified to provide optimum reservoir development in the 14.0 sand. As a result, a horizontal well simulation study to support the requirement for horizontal wells has been carried out. The objectives of this study were to confirm the reserves and performance of the horizontal wells as compared to conventional wells and at the same time understand the key parameters that influence the horizontal well performance. Due to the lack of production history for this reservoir, in addition to no representative core and PVT data, the challenges lay in acquiring the most representative data to be used in the simulation study. This paper describes the approach taken in the simulation; from utilising core and PVT data from neighbouring fields, establishing a geological layering based on well log correlations and finally the setting up of the simulation model and grid system. In addition, prediction runs and sensitivity studies are also discussed, which identified the key parameters that impact horizontal well recovery and performance. The base case results confirmed the merits of a horizontal well development as compared to conventional wells. They also support the reserves, watercut and GOR performance of a horizontal well as derived from analytical calculations. However, the simulation gave new insight into the declining gross production. The sensitivity studies highlighted the need to obtain core data and fluid samples during development, for use in future simulation studies. Introduction The Baram Field is situated approximately 25km. off-shore Lutong, Sarawak, Malaysia, in about 40 to 200 ft of water (Figure 1). It is the largest and most structurally complex field in the Baram Delta Province, with in excess of 750 identified hydrocarbon bearing reservoirs. The structure is an elongated, East-West trending anticline which could be sub-divided into major and complexly faulted down-thrown blocks (‘A’ and ‘B’ Areas), and a simple, low relief up-thrown block closed against the main Baram Growth Fault (‘South’ Area) (Figures 2). The prospective interval ranges in depth from 2,500 ftss. (shallow I reservoirs) to 9,000 ftss. (deep S reservoirs); and consists of alternating sand and shale sequences deposited mainly in coastal, coastal fluviomarine and fluviomarine inner neritic environments. P. 455
- Geology > Structural Geology > Fault (0.75)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.54)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.48)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Phase behavior and PVT measurements (1.00)