Abstract

Petrophysics coupled with rock physics studies are significant in the evaluation of well and field potential, and to construct subsurface models based on rock properties. This case study combines petrophysics and fluid substitution modeling for reservoir characterization of the producing Datta Formation in the Chanda oil field of Kohat Basin. The Datta Formation interval of two wells, Chanda-1, and Chanda Deep-1, is analyzed to calculate petrophysical parameters including gross thickness, net thickness, net to gross ratio (NGR), porosity (PHA), permeability (K), and water saturation (SW). The Datta Formation represents fair to good porosity in the range of 7–13%. Water saturation shows low values lying in the range of 31–36%. The formation is interpreted from gamma ray (GR) log trends, where sand packages dominantly represent a left box-car and irregular trend. Cross-plots, such as density porosity (RHOB-NPHI), gamma ray-density (GR-RHOB), gamma ray-porosity (GR-NPHI), and thorium–potassium (Th–K), were used for lithological identification in the studied wells, and indicated arkosic and micaceous sandstone as the dominant lithology with shale. Evaluation of petrophysical parameters shows that the Datta sands have high hydrocarbon saturation in the area. The fluid substitution modeling was applied to clastics of the Datta Formation for field development. One hydrocarbon-bearing zone (zone 1) was identified in Chanda-1, while four hydrocarbon-bearing zones (zones 1, 2, 3, and 4) were identified in Chanda Deep-1. Fluid substitution results at the Datta level showed that the P-wave velocity and density varied when the hydrocarbon phase was substituted completely with water. With the substitution of brine with oil, there was a change in compressional wave velocity (Vp) and a decrease in density (RHOB), while the shear wave velocity (Vs) was stable and unaffected by the change of fluid density and saturation. The results of this research could be used to predict saturation types of reservoir using seismic data and to identify pay-zones, and map reservoir saturation to drill for oil and gas.

Highlights

  • The Chanda oil field in Khyber Pakhtunkhwa, Pakistan, marks the first advent of an era of hydrocarbon exploration in the province since its discovery in 1998–1999

  • The net thickness is the thickness of the reservoir, which was determined by defining the non-reservoir and reservoir intervals of sands, based on the baseline

  • The thickness of shale within the reservoir sands was obtained, and that value was subtracted from the gross thickness

Read more

Summary

Introduction

The Chanda oil field in Khyber Pakhtunkhwa, Pakistan, marks the first advent of an era of hydrocarbon exploration in the province since its discovery in 1998–1999. Pivnik and Wells (1996) indicated that the Panjal–Khairabad Thrust Fault is a division between the northwest Himalayan zone (Foreland) and deformed and metamorphosed northern zone (Hinterland). Some of the low-angle thrust faults have been folded and form klippe These constitute a distinct thrust belt referred to as the Mir Khwali Sar Trust Belt (MKSTB) which, according to Pivnik and Sercombe (1993), is a compression-related, relict, thin-skinned thrust belt. A large thrust fault called Hukni Fault traverses the area. This fault is located above a north–south lateral ramp, in the basement, and the swing in a strike near Shakardara records a progressive fading away of the lateral and frontal ramp complex at depth (Abbasi and McElroy 1991)

Objectives
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call