Wang W.,Chuanqing Drillng Engineering Co. |
Liu X.,Chuanqing Drillng Engineering Co. |
Gao P.,Chuanqing Drillng Engineering Co. |
Yang X.,Chuanqing Drillng Engineering Co. |
Huang T.,Chuanqing Drillng Engineering Co.
Natural Gas Industry | Year: 2011
Previous understandings of the Asmari carbonate reservoir in the MIS Structure, Middle East, are restricted by technical conditions, data availability and accuracy. A thorough study is performed on this reservoir by using the newly available data including outcrop observation, ordinary thin section, cast, scanning electron microscope, scanning CT, image logging and fracture prediction. The following new understandings are obtained. (1) The main reservoir rocks are fine to very fine crystalline dolomites formed by early dolomitization. (2) Not only do the dominant types of reservoir space have secondary dissolution pores and vuggs resulted from late dissolution; but the dolomite reservoirs with well-developed dissolution pores and vugs have a good petrophysical property. (3) As a whole, the matrix reservoirs in the upper Asmari Formation are characterized by vertical superimposition of multi-layered reservoir intervals and lateral continuous distribution of the major reservoir intervals. (4) Tension structural fractures resulted from Alpine orogeny are well developed and are dominated by vertical fractures with orientation in parallel with structural trend (N45°W). However, the levels of fracture development are different at either structural locations or reservoir intervals. (5) The combinations of fractures of different occurrences constitute fracture networks. The fracture networks in connection with dissolution pores and vuggs form good fracture-vug seepage flow system, leading to the formation of high quality fracture-vuggy carbonate reservoirs.