An analysis of influential factors to the development of tight gas sands by multi-stage fractured horizontal wells---A Case study in Sulige gas field

With large recourses in the world, tight gas sands have become hotspots to increase reserve and production for many countries in recent years. However, under the current economic and technological conditions, its recoverable reserves and productivity of individual wells are still lower. Staged fracturing horizontal well technology can effectively improve the contact area of production intervals and reservoirs, increase well productivity, and reduce the drilling wells. However, the domestic study on development indicators and production performance of the technology in tight gas sands is limited. This paper takes Sulige gas field --the largest gas field in China--as an example. For geological features in such gas fields, by using methods of numerical well-test simulation and economic evaluation, taking initially absolute open flow (qAOF), cumulative gas production/recovery factor and internal rate of return (IRR) into account, the optimum parameters of the reservoir, drilling, completion wells and stimulations for multi-stage fractured horizontal wells are obtained. Introduction Currently, unconventional gas resources, especially the development of tight sandstone gas are highly paid more attention in the world. With vast areas of tight gas exploration, rich in resources in China, it has become an important force in natural gas supply and will continue to be the highlight of reserves and production growth. On proved reserves and technical strength, the exploration and development of tight sandstone gas is the most realistic sense in unconventional gas fields in China [1] . There are large tight gas recourses in the world. However, under the current economic and technological conditions, its recoverable reserves and productivity of individual wells are still lower. It is difficult to develop effectively these kinds of reservoirs in large scale. Staged fracturing horizontal well technology can effectively improve the contact area between well completion and reservoir, which increase well productivity and reduce drilling wells. However, the study on production performance of multi-stage fractured horizontal wells is limited in China. This paper takes Sulige gas field as an example. Considering the geological features in such gas fields, by using methods of numerical well-test simulation and economic evaluation, taking initially absolute open flow (qAOF), cumulative gas production/recovery factor and internal rate of return (IRR) into account, the optimum parameters of reservoir, drilling, completion wells and stimulations for multi-stage fractured horizontal well are obtained. Modeling and parameter selection Parameters of reservoir and gas wells Sulige gas field is the largest gas field in China. It is typical fluvial tight sandstone gas reservoir, and the effective sand bodies are the isolated lenticular distribution. It is characterized as a fine-grained tight gas with clean to dirty sands of found to be interbedded with thin shale streaks at depth ranging from 2700m to 3400m. Permeability ranges from 0.05md and 1.0md, while porosity values lie between 4% and 14%. Figure 1and Figure 2 are the distribution of dynamic reserves and drainage width and length of individual wells in eastern Sulige, separately [2-3] .