2-D Seismic Interpretation and Petrophysical Analysis of Dhodhak Well 03, Central Indus Basin, Pakistan

Abstract

The present study pertains to the modeling of the productive zones from seismic and well-log data. This was carried out by using seismic lines, 795-SK-05R, 795-SK-06, 795-SK- 11A, 795-SK-18, and well log data of Dhodhak-03 provided by the Directorate General of Petroleum Concession (DGPC). The Dhodhak gas field is the Pakistan’s largest gas and condensate-producing field. The Dhodhak field, with estimates of 620Bcf of proven gas reserves and 30 million barrels of condensate, is located in the Central Indus basin approximately 15 North of Safed Koh Block. The area lies in the Middle Indus basin and the reservoir encountered during the study of well Dhodhak-03 is Pab Sandstone Formations. The present study area is the Dhodhak Gas condensate field which is located in the tribal area of Dera Ghazi Khan, about 230 km northwest of Multan. This field was discovered in May 1976 by Oil and Gas Development Company Limited (OGDCL) in the gas field of the Punjab platform and was brought on regular production in December 1994. The gas condensates are most likely fluid types. During the study of Seismic sections first of all we pick a prominent reflector from the seismic sections. During the interpretation of the present study, one reflector was marked at a different time R (Pab Sandstone Formation) then we noted the two-way travel time (TWT) of this reflector against the shotpoints. Moreover, we have done manual preparation of the time and depth contour map of the Pab Sandstone formation on the base map. The formula used for the conversion of time into depth is given below: S = V*T/2 In Petrophysical studies first of all we identify Reservoir zones and determine Reservoir parameters that are Volume of Shale, Porosity (RHOB values and NФ or Sonic readings), Resistivity of Water, Water Saturation, Hydrocarbon Saturation, Lithology or Mineral Identification (by calculating the M and N values). During petrophysical interpretation, different cross plots were constructed like porosity, volume of shale, Hydrocarbon4 saturation, and Water Saturation against depth interval which shows the behavior of the reservoir which is the key interest zone. The reservoir quality of the Pab Sandstone Formation was much better in terms of clean Sandstone, porosity, water saturation, and permeability.