Hydrocarbon recovery from conventional reservoirs is decreasing and the need to produce oil cheaply from mature, marginal and unconventional reservoirs poses a big challenge to the oil industry today. Non-Conventional well technology can provide solutions to these problems and may prove to be a beneficial tool for the oil industry. Many non-conventional projects demonstrate that this technology accelerates well productivity and improves recovery. In addition, numerical simulation results show that multilateral wells usually help improve the cumulative production from a reservoir as compared to conventional wells. There are however some limitations which should be taken into account before applying this technology. Such benefits and limitations will be discussed in this thesis. The thesis objective is to investigate whether non-conventional wells increase oil recovery of matured fields or not. The selected field is 103E; one of the Zueitina Company fields in Sirte Basin of Libya. 103E contains many reservoirs. One of them is Upper Gir reservoir which is a good candidate for non-conventional well technology. This objective can be proved using different reservoir simulation tools). Based on a static model that was built using Petrel software, a dynamic model using SURE software was created. Using SURESim simulator, different scenarios of various well types (vertical, horizontal and multi-lateral wells) were investigated. For all scenarios a 25 years forecast was calculated.