Modern clastic depositional environments and the Lower Goru and Sembar Reservoirs of Pakistan

Course Details

As nice as it is looking at outcrops and interpreting their environments of deposition and relating those to sub-surface reservoirs, the best way to develop a thorough understanding of the processes that influence reservoir presence, distribution and quality is to look at modern systems. Having looked at seismic, well-logs and core data from OGDCL, POL, and UEPL we conclude that the primary reservoir targets within the Lower Goru comprise of tidal channels, tidal inlets, creeks, shorefaces and barrier island sandstones.

The upper portion of the Lower Goru represents a transition from deltaic to estuarine
conditions (sigmoid, top-truncated clinoforms in the lower part, sub-parallel, continuous, variable amplitude reflection configuration in the upper part). The reservoirs are only a snap-shot in this evolution from regressive to transgressive conditions.

The modern coastline of Karachi makes an excellent analog for a variety of reasons. Damming of the Indus in the 1950s has resulted in a decrease in discharge of 80% (Milliman et al., 1984). Away from the active channel effluent the delta is undergoing transgression due to a decrease in sediment supply, subsidence and a eustatic sea-level rise.

The three-day field trip will not only introduce participants to processes, but will leave a lasting impression of the heterogeneity associated with such reservoirs.

This is the second in a series of the three field courses designed to prepare you for the challenges in the Sembar and Lower Goru Reservoirs of Pakistan. Once you have completed this ‘awareness-level’ course we encourage you to take the ‘skill-level’ course.

WHO SHOULD ATTEND

This is an ‘awareness’ level course that we recommend for all experience level geologists, geophysicists, petrophysicists, engineers and managers. The course starts and ends in Karachi, Pakistan and introduces participants to the processes that control reservoir deposition, preservation, distribution and architecture in shallow marine settings.

Course Outline

Day 1

We will be meeting at the hotel room for lectures on field safety, and sedimentary structures found in fluvial and shallow marine successions.

We will begin by examining an estuary in detail starting from landward to basinward. Facies associations of tidal channels, creeks and inlets will be discussed with several sub-surface examples including spectral decomposition images and well logs.


Day 2

We will gather at the hotel meeting room for lectures on clastic sequence stratigraphy

On the second day we will head to the Upper Delta Plain of the modern Indus. Participants will get an opportunity to investigate the turbidity maximum zone and its effect on reservoir quality of distributary channels. We will also discuss "overbank" environments including sand flats, mixed flats and mud-flats.


On the Lower Delta Plain we will discuss the process of lateral accretion and its role in compartmentalizing point bars associated with high-sinuosity distributary channels.

Day 3

We will gather at the hotel meeting room for a workshop on the identification of depositional environments using well-logs. Although the instructor will bring a collection of logs from basins outside Pakistan, we strongly urge you to bring in your data work on.

We will be using a boat to visit one of the many mouthbars of the Indus Delta right at the Delta Front. From the boat we will be collecting samples of the distributary channels and comparing grain-size and sorting with sands on the mouth bar. We will also be examining a spit-bar and the evolution of lobes from active to abandoned and the effect that can potentially have on reservoir distribution and quality.


This field trip is run upon request only and requires a minimum of 10 participants. The cost per participant is #3500 and this includes 3 nights hotel stay in Karachi, all meals, boat and vehicle costs, fuel, tuition, field guide and exercise materials.

We have been asked why our field trips are so expensive. We guarantee you will learn more about the sedimentology and sequence stratigraphy of your reservoirs in the 3 days you spend with us than the past 3 years you have spent in the office, if you don't agree we will be happy to refund 50% of your tuition payment.