This thesis deals with the Integrated Asset Modeling (1AM) of OMV giant gas field Sawan located in Sind Province of Pakistan. First, details of Sawan field to the standpoint of Geological, Geophysical, Reservoir and Production operations aspects are discussed in length, major studies and operational activities has been focused here to build the overall insight of the Sawan field to the readers. Later, integrated asset modeling approach has been discussed in length. Integrated asset modeling has been used to evaluate the ultimate economic gas recovery with & without any capital expenditure, possible compression timing and evaluating operating strategies for Sawan gas field on-shore Pakistan. MBAL (Material Balance) and PROSPER well models were linked to a Pipeline and surface Network Module GAP of Petroleum Expert suite PETEX 5.0. Asset modeling allowed the impact of interference of reservoir, wells and surface network system. Modeling also quantified constrains limit given to the different pressure calculation nodes. Compression starting time also devised when the productions plateau go below to the maximum plant capacity, compression facility sustains the maximum plateau for significant period of time. With the investigated cases the ultimate economic recovery of gas could be enhanced 82% as compare to the base case where, existing plant without any significant change only able to produce 68% of total gas initially in place. MBAL (Material Balance) reservoir model for proven gas reserves P90 has been history matched. Existing producing and future development wells have been modeled in PETEX suit PROSPER with the most recent acquired well test data. Each well has been created in prosper and its subsequent bottom hole pressure with respect to the corresponding flow rates have been matched with the correlations having least standard deviations. Inflow Performance Curves (IPR) and Vertical Lift Performance (VLP) of each well have been generated and well matched with the test points in same graph. IPR gives the well flowing pressure as a function of flow rate, while VLP describes the relation between bottom hole (i.e. sand face pressure) as a function of flow rate. Additionally IPR of fractured well has been created. In GAP module of PETEX, both reservoir and well models are integrated and linked to the surface network system of flow lines, well head coolers, compressors and separator. A sensitivity analysis of compression ratio with its subsequent impact on ultimate recovery has also been investigated. Quality control of developed models has been done in depth.