Estimation of Initial Oil in Place by the Material Balance Method for A Solution Gas Drive Reservoir

Author(s):  
Mihir K. Sinha ◽  
Larry R. Padgett
2011 ◽  
Vol 14 (06) ◽  
pp. 750-762 ◽  
Author(s):  
Nicolas Legrand ◽  
Joop de Kok ◽  
Pascale Neff ◽  
Torsten Clemens

Summary The fractured basement field in Yemen described in this paper is characterized by two types of fracturing: background fractures with a very low effective permeability of less than 0.001 md and fracture corridors with an effective permeability of up to several millidarcies. Except for some dissolution porosity related to fracture corridors, no significant matrix porosity is encountered (total porosity is only 1.15%). Approximately one-half of the oil in place is contained in the fracture corridors and one-half in the background fractures. Production from this field commenced in 2007. It is currently produced by depletion. Compositional grading has been observed in the 3,120-ft oil column. Despite the fact that the oil is close to bubblepoint pressure at the top of the reservoir, a moderate increase in gas/oil ratio (GOR) has been seen. Detailed studies using material balance and discrete-fracture-network (DFN) models revealed that the reason for the slow increase in GOR is the low permeability of the background fractures. The low permeability leads to viscous forces being dominant over gravity forces and, hence, limited gravity segregation of gas and oil. Because of the relatively small viscosity difference between the gas and the oil in this field(µo/µg = 6.5), the gas mobility is not much higher than the oil mobility at low gas saturations. Hence, oil and gas are produced effectively from the background fractures into the fracture corridors and the reservoir pressure is not depleting as fast as in reservoirs with higher viscosity difference between gas and oil. This results in a more effective solution-gas-drive recovery mechanism than that expected for a conventional reservoir. A number of reservoir-management strategies have been investigated. The results indicate that the low permeability of the fracture corridors and very low permeability of the background fractures lead to low recovery factors of 14% for gas injection. However, the efficiency of solution-gas drive is higher than in conventional reservoirs.


Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 412-418
Author(s):  
Xiao Qianhua ◽  
Wang Zhiyuan ◽  
Yang Zhengming ◽  
Liu Xuewei ◽  
Wei Yunyun

Abstract The variation of porous flow resistance of solution-gas drive for tight oil reservoirs has been studied by designing new experimental equipment. The results show that the relation between the porous flow resistance gradient and pressure is the exponential function. The solution-gas driving resistance is determined by a combination of factors, such as the gas-oil ratio, density, viscosity, permeability, porosity and the Jamin effect. Based on the material balance and the flow resistance gradient equation, a new governing equation for solution-gas drive is established. After coupling with the nonlinear equation of elastic drive, the drainage radius of solution-gas drive is found to be very small and decreases rapidly when the bottom-hole pressure approaches the bubble-point value. Pressure distribution of the solution-gas drive is non-linear, and the values decrease sharply as it approaches the well bore. The productivity is rather low despite being strongly influenced by permeability. Therefore, stimulated reservoir volume (SRV) is the essential measure taken for effective development for tight oil reservoirs.


2004 ◽  
Author(s):  
Cengiz Satik ◽  
Carlon Robertson ◽  
Bayram Kalpakci ◽  
Deepak Gupta

Author(s):  
Tri Handoyo ◽  
Suryo Prakoso

<em>The success of the discovery of new structure Akasia Bagus with potential L layer in 2009 at PT Pertamina EP's Jatibarang Field was followed up by the drilling infill wells with Plan of Development (POD) mechanism which is currently in the process of drilling the last well. The basis of the L layer hydrocarbon calculation in place on the POD is a static analysis. The wells currently produced are still able to flow with natural flow and enough production data since 2009 this structure was found. This study will present an analysis of production in the L layer of Akasia Bagus structure for Original Oil In Place (OOIP) updates using the conventional material balance method and then carry out the best development strategy to optimize oil production. Economic analysis is also carried out for reference in making decision on which scenario to choose. The conventional material balance method gets an OOIP value of 17.36 MMSTB, with the drive energy ratio being 5:3:2 for water influx : fluid expansion : gas cap expansion. Three (3) production optimization scenarios were analyzed, the results showed that the addition of 2 infill wells reached Recovery Factot (RF) of oil up to 23% of OOIP, minimal water production and attractive economic results.</em>


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