| Reservoir of Hongqian-1well block in Qigu formation is an extra-heavy oil reservoir. Steam injection is very suitable for the reservoir due to its thin net pay and high viscous crude oil. The mechanism of steam flooding is characterized by viscosity reduction and oil relative permeability improvement as the result of heating, thermal expansion, distillation, miscible-phase displacement and emulsifying displacement. Good effect of steam huff-puff has been gained in this well block, but steam flooding receives less expected effect. After20years of steam injection, the oil recovery in this block is only17.1%, which shows that there is still a potential for adjustment.Based on the comprehensive study of logging analysis, lab analysis and coring analysis, many works have been conducted, such as the structural and depositional analysis, reservoir characteristic, petro physical analysis and reserves calculation. Through comprehensive research on mechanism of steam injection, the convert conditions and time between steam flooding and steam huff-puff is studied. Taking advantage of production data, the current situation in the block was studied. And then the effect of steam injection development has been evaluated and the main problems encountered during the production are found. On the basis of monitoring data, sealed-coring data, analysis of water flooding zones, numerical simulation and production performance analysis, planar and sectional distribution of remaining oil has been studied and then the target block for adjustment have been selected. Based on the results of study on heating radius, sealed-coring saturation, pilot test and numerical simulation of infilling drilling cases, Qigu formation in Hongqian-1well block is considered feasible for infilling drilling.In Hong-1and Hong-4Block two typical areas are selected for numerical modeling. Using the numerical model the adjustment after the infilling is studied. Firstly, history matching is conducted to analyze the residual oil distribution and temperature field. The favorable area is determined for infilling drilling development through steam stimulation prediction. Secondly, the oil recovery of steam huff-puff and steam flooding are respectively calculated using empirical formulas and furthermore the development pattern after the infilling is also studied. And then, the corresponding parameters are selected and production indices and designed productivity for individual wells are predicted by means of numerical modeling. At last, combined with practical conditions of reservoir the development adjustment strategy and production and injection rate proration are determined. |
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