Integrated Development Strategy for Different Kinds of Stratified Reservoirs with Edge Water and Complicated Faults in Niger

Abstract

This paper demonstrates an integrated approach to development in high efficiency for different kinds of stratified reservoirs with edge water and complicated faults in Niger, which is located in landlocked west Africa. In recent years, a great number of stratified reservoirs with different reservoir characteristics have been discovered in Niger. All these oilfields could be divided into three categories: gas cap reservoir, edge water reservoir with strong energy support and edge water reservoir with weak energy support. One oil-bearing block with large reserves is selected as the pilot field from each type of reservoirs respectively. To achieve good development effects for these pilot reservoirs, an integrated approach is adopted combining water or gas controlling technology with three dimensional oil potential exploiting strategy. According to peculiar production problems of each reservoir, specific strategy is resorted to improve development performance. For gas cap reservoir, single sand bodies are specified and reservoir types of sub-layers are detailed researched according to gas cap index calculation. Development sequence of oil production prior to gas production is put forward and reasonable oil recovery offtake rate is optimized to avoid gas breakthrough. For edge water reservoir with strong energy support, with combination of static geological and dynamic data analysis, water breakthrough position could be identified and squeezed. For edge water reservoir with weak energy support, feasibility and necessity of water injection is demonstrated and related water injection parameters are optimized such as water injection timing, injection well pattern, water injection rate and injection-production ratio. In addition, development strategy of production relay layer by layer is adopted to realize successively producing remaining oil between layers for the three stratified reservoirs. With applying the integrated approach above, production plateau of the three typical oilfields is prolonged and oil production is also increased. Successful development of the three typical oilfields provides valuable ideas and references for the effective development of other similar enormous reservoirs in Niger.