Wathiq Jassim Mohammed Al-Mudhafer

Combining Design of Experiments and Streamline-Based Simulation for Efficient Thermal IOR Development Study in a Waterdrive Light Oil Reservoir

Steamflooding has been widely applied as an e↵ective way to improve oil recovery not only in heavy oil reservoirs, but also in light oil reservoirs. It has been investigated that Steamflooding is a good way to handle the formation’s heterogeneity by decrease the degree of fluid spread and distortion in addition to extract bitumen that might be found in light oil reservoirs as in the reservoir under study. This reservoir is a sandstone formation in South Rumaila oil field located in Iraq. This field, with a 58-year production history, has 40 production wells and is surrounded by an infinite active edge water aquifer from the east and the west flanks. Because of some discontinuous series of bitumen at the east flank, the strength of east flank is much e↵ective less than the west one. In this study, a comparative thermodynamic simulation study has been conducted to investigate the feasibility of Steamflooding to extract the bitumen and improve oil recovery and determine the optimal future development scenario considering design of experiments and streamline-based simulation results. First of all, a thermodynamic reservoir simulator has been used to find out the feasibility of steam flooding in the heterogeneous reservoir to extract the bitumen and improve oil recovery. Later, full factorial design (FFD) has been conducted to figure out the most factors a↵ecting the response (recovery factor) through Steamflooding with distinct levels. The factors are steam injection rate, quality, temperature, and number of steam injectors. FFD has shown that the recovery factor is sensitive for all the mentioned factors as well as some interactions and it also shown that the optimal scenario has the highest steam quality, injection rate, and temperature with the lowest number of injectors to get the highest recovery factor. Consequently, and in order to determine the optimal number of injectors, a connectivity matrix between the injectors and producers has been constructed to provide a source of potential injection wells to be optimized. This matrix has been set based on the streamline-based simulation results at the first time step of the prediction period and the wells were selected according to the higher connectivity with the producers. This practical optimization approach has led to determine the optimal number of steam injection wells that leads to optimal development scenario. It has shown finally that only one injector, which has higher connections with the main producers in the field, has led to highest oil recovery.

Comparative Experimental Design of Steamflooding for Optimal Efficient Performance of a Heterogeneous Light Oil Sandstone Reservoir

Steamflooding has been widely applied as an effective way to improve oil recovery not only in heavy oil reservoirs, but also in light oil reservoirs. Its efficiency comes from its influential rule to enhance oil displacement by flourishing the reservoir and fluid properties. Also, it has been investigated that Steamflooding is a good way to handle the formations heterogeneity by decrease the degree of fluid spread and distortion. The reservoir under study is a sandstone formation in South Rumaila oil field located in Iraq. This field, with a 59-years production history, has 40 production wells and is surrounded by an infinite active edge water aquifer from the east and the west flanks. The east flank is much less effective than the west one because there are some discontinuous amounts of bitumen close to the oil-water contact that impedes the aquifer water approaching into the reservoir. The formation depth is 10350 ft. sub-sea with a maximum vertical oil column of 350 ft. The average bubble point pressure is 2660 psi and the average reservoir temperature is 210°F while oil density is 34°API. In this study, a comparative thermodynamic simulation study has been conducted to investigate the feasibility of Steamflooding to extract the bitumen and improve oil recovery and also to determine the optimal future reservoir performance with comparative designs of experiments considering the recovery factor as a response function. Firstly, the thermodynamic reservoir simulator (CMG-STARS) has been used to figure out the feasibility of steam flooding to increase the recovery factor by the end of 12 years future prediction period in comparison with the base case of primary production. Then, nine different experiments within three-levels & four-factors have been set within the orthogonal arrays design (OAD) to get some idea about the factors controlling the reservoir performance. The factors are steam injection rate, steam quality, steam temperature, and number of steam injectors. The regression model of Orthogonal Arrays Design (OAD) has shown that the recovery factor is sensitive only to steam injection rate and number of injectors and the optimal scenario has the highest steam injection rate and the lowest injectors to get the highest recovery factor. Then, the Full Factorial Design (FFD) has been adopted for the same factors, but with distinct levels to formulate 36 high dispersion experiments. The levels of injectors have been selected based on the high connectivity with the producers based on the streamlines-based simulation results after construction such a connectivity matrix between the injectors and producers. The regression analysis of FFD has shown that all the four factors and some interaction among them have a significant effect on the response and the optimal scenario that has the highest recovery factor, has the same levels of the four parameters as what has been obtained from the

Parallel Estimation of Surface Subsidence and Updated Reservoir Characteristics by Coupling of Geomechanical & Fluid Flow Modeling

Determining of reservoir surface subsidence is a crucial problem especially for soft and unconsolidated formations. For long time production with water injection and/or water influx, the pore pressure decreases with increasing in effective stress leading to reservoir compaction and vertical surface subsidence. In this paper, a Tank Capacitance-Resistive Model (TCRM) has been done to estimate the history of vertical subsidence in the upper sandstone member/main pay of South Rumaila oil field in Iraq. It is a mature oil field with around 58 years of production with 40 producing wells and it has also 20 injection wells located only at the east flank. The average surface area for this reservoir is 142 km2. The reservoir is modeled considering an infinite acting aquifer at the east and west flanks. A commercial reservoir simulator has been adopted parallel with the Tank Capacitance-Resistive Model to estimate the subsidence in very active aquifer. The Carter-Tracy water influx model has been adopted to calculate the water influx rate. The TCRM depends on the concept of continuity equation that considers the difference between the water injection and oil production as reservoir input and output, respectively. So, the simulator calculates the total water injection rate and water influx to be treated as water injection in the continuity equation. The results demonstrated that reservoir formation has plastic deformation because it has recurrence subsidence in the reservoir thickness. The current subsidence for this reservoir in the current time after 58 years of predict is 1.5 ft at the crest of the reservoir and it is approximately close to the local subsidence at each grid in the reservoir crest.