A modelling study of horizontal wells with multiple hydraulic fractures in low permeability formations.

摘要

Due to the increasing global demand of oil and natural gas resources and the limited reserves of conventional reservoirs, the need for exploring untapped energy resources continues to become increasingly important than ever before, this has paved the way for oil and gas companies to explore low permeability reservoirs in recent years. Researchers and leaders in the industry have found that a decline in oil and gas production from conventional medium to high permeability formations have to be replaced by development and production of oil and gas from low permeability formations.;Production from low permeability formations has been and continues to be challenging and costly for the oil and gas industry. However hydraulically fractured horizontal wells are the proven technology to produce economically from low permeability formations. Despite the challenges facing oil and gas producers in producing from low permeability formations, only a few number of numerical studies have been done regarding the flow behaviors in low permeability reservoirs, particularly in regards to the dominant flow regimes and how formation and fracture properties affect these flow regimes.;This modeling study will focus on identifying the effects of multiple hydraulic fractures on flow regimes and gas production from low permeability reservoirs. Low permeability reservoirs present various challenges to understanding and modeling since they require fracture stimulation which creates complex flow profiles.;A model was designed using a numerical reservoir simulator model, with a single porosity, tight permeability, hydraulically fractured horizontal wells and desorption. The different flow regimes which occur over the initial 3 to 5 years (most economically critical production period) were identified. The flow regimes were analyzed using production rate plots and comparing results to pressure derivative plots. The production rate plots were used to illustrate the different flow regimes and their transitions (in most cases) in low permeability horizontal fractured systems. Various possibilities of low permeability horizontally fractured models were examined with desorption. It was determined that as a result of the ultra tight permeability of the formation, the production behavior is dominated by the configuration and extent of the hydraulic fractures.;Overall this thesis provides us an in depth understanding of flow behaviors in low permeability formations, where such understanding can be employed to estimate production from low permeability formations.