MAXIMIZING THE EFFECTIVENESS

OF TIME-LAPSE (4D) SEISMIC :

NIGER DELTA AS A CASE STUDY

AKPOGUMA V. MUDIAGA

DECEMBER,2014

INTRODUCTION

WHAT IS TIME-LAPSE SEISMIC?

STEPS IN ACHIEVING TIME-LAPSE SEISMIC DATA

EFFECTIVENESS OF TIME-LAPSE SEISMIC

CASE STUDIES IN NIGER DELTA

MAXIMIZING TIME-LAPSE IN NIGER DELTA

CONCLUSION

OUTLINE

INTRODUCTION

What if your company is offered a tool that can tell you if a field is:

Performing according to plan

Help you locate undrained hydrocarbons,

Optimize infill-well and

Help ensure maximum recovery of Crude.

Would you purchase that tool?

The cost is less than that of drilling a single well.

If you might guess, the tool is 4D (time-lapse) seismic Technology

The 4th Dimension is just time. The time is calendar

time and not geological time.

In short, while 3D is a snapshot, 4D is a movie.

WHAT IS TIME-LAPSE SEISMIC ?

4D, or time-lapse seismic, is a series of repeated seismic

surveys used to aid the description and understanding of a

reservoir as it changes over time. Changes in the reservoir

properties such as fluid saturation and pressure, result in

changes in the elastic properties can be detected under

favorable circumstances by the seismic data.

WHAT IS TIME-LAPSE SEISMIC?

The 2D/3D is called the Baseline survey while the 4D seismic is the

Monitor Survey

Am

plitu

de

Early timeLater time after

productionDifference

-

Example of a Time-Lapse Survey

WHAT IS TIME-LAPSE SEISMIC ?

After Ubeku 2005

Feasibility study

Acquisition

Processing

Inversion & Interpretation

STEPS IN ACHIEVING TIME-LAPSE SEISMIC DATA

Feasibility study

Feasibility study answers questions like:

Will 4D work in my reservoir?

What is the expected benefit of 4D survey?

When should I carry out my 4D?

Rock physics modelling, geological modelling and reservoir

simulation modelling are all done at this stage

Acquisition

Processing

Key factors in processing

Mute application.

Pre-stack de-convolution

parameters.

Pre-stack, multi-channel noise

attenuation (amplitude).

Imaging Velocities – NMO and/or

migration velocities.

After Ubeku 2005

Inversion and Interpretation

For 3D seismic data, we tie seismic to well-log synthetics. For

4D data, however, we tie our interpretation not only to the well

logs but also to the dynamic reservoir information, such as

production and injection, flow simulation, and repeat logs.

The interpretation is focused on the production &

development stages of a field and is concerned with changes

in the reservoir, usually the fluid content and movement

within the structures.

EFFECTIVENESS

Carbon Capture Sequestration and Environmental Monitoring

Update Reservoir Models

Locate New Wells & Tap Undrained Hydrocarbon.

Monitor Enhanced Oil Recovery Projects

Increase Hydrocarbon Production & Reserves

EFFECTIVENESS

GeoExpro 2009

EFFECTIVENESS

Ubeku 2005

CASE STUDY OF 4D IN NIGER DELTA

Bonga Field

OML 118 (from OPL 212)

120km offshore 1000m

water depth

After Johnston 2010

The Bonga field was discovered in 1995 and the Bonga-1 discovery well was the first well

drilled

First seismic acquisition was by streamer in 1993.

The baseline survey was acquired in 2000 by also a 3D seismic streamer survey

First oil production started in November 2005 and Bonga has an average production of

20,000 barrels/day.

Oil production is from 4 main stacked turbidite reservoir (690, 702, 710/740 and 803)

using pressure maintenance via water injection through producer and injector well pairs.

Bonga Field

Bonga Field

After 2 years of production, the first 4D (streamer survey) was

acquired successfully in 2008 and this was Nigeria first 4D survey in

deep waters.

The Repeat seismic survey was planned to understand reservoir

sweep through time (after 2 years of production) and enable better

well placements such that the Bonga Field life-cycle production will

be maximized.

The 4D results of this survey added significant value to the

development of the asset by improving the understanding of the

reservoir connectivity and swept efficiency between injector and

producer wells, making the project a clear technical and business

success.

2000 2008

Bonga Field

International Petroleum Training Conference 2013

Difference

Although, No 4D response was expected in the undershoot

region during the time the first monitor was acquired, this

area contain significant reserves (800mb STOIP) and will be

require good 4D data quality in the near future to be able to

effectively monitor the updip Reservoirs.

For better monitoring of the updip reservoir, in 2010,

SNEPCo acquired an Ocean Bottom Node (OBN) survey

around the Bonga main FPSO and SPM area to serve as a

Baseline for the future OBN surveys.

Bonga Field

Bonga Field

International petroleum training conference 2013

Meren field

After Lumley 2000

The Meren field (OML 95 of Niger delta) is operated by Chevron and is

located in shallow water (50 feet deep) in south-east of Lagos ,Nigeria

about 10 miles offshore.

Meren field was discovered in 1965 and first production began in

1968, and has over 80 producer and injector wells.

The baseline seismic survey was a 1987 Chevron legacy 3D survey

while the 4D survey was short in 1996.

Meren field

Three areas within the

E303 that may contain

major bypassed oil

reserves were identified

flowpaths of water

through the injector

wells were understood.

This enabled drilling of

new wells.

Meren field

Lumley 2000

OFON field Block OML102 offshore

The Ofon field is

located in Oil Mining

Lease OML 102,

offshore Nigeria in

40 meters water

depth operated by

Total E&P and

NNPC

Production began in the Ofon field in 1997 and has produced over 200

million barrels of crude oil.

OffshoreEnergyToday.com 2012

The base survey was a 3D marine dataset recorded between 1990 and 1992 by DIGICON with

a dual source and one streamer configuration, a nominal stacking fold of 30, a cable length of

3000m, and an acquisition bin of 6.25m x 25m

The repeated survey was the 3D OBC 2C seismic recorded in 2004, employing 4 ocean

bottom cables per swath, shot along the cables with maximum offsets of 4000m and nominal

stacking fold 120 for a 12.5m x 25m bin size.

The two seismic acquisitions were very different in terms of data quality (azimuths, Signal to

Noise ratio, fold coverage, radio navigation and positioning quality).Because of this, special

attention was paid, during the processing.

OFON field Block OML102 offshore

OFON field Block OML102 offshore

3D Section:

Minimum Amplitude Full OBC

4D Section : Difference between Minimum

Amplitude “OBC – Streamer”After Castex et al 2007

MAXIMIZING 4D SEISMIC IN NIGER DELTA

Considering the role of 4D seismic in Enhanced oil recovery, 4D seismic will also have a role in meeting our target.

From 2.5M bbl/d in 2012 to 4 Mbbl/d in 2020

Maximized EOR will be key for Nigeria

After Al-Khatib 2013

MAXIMIZING 4D SEISMIC IN NIGER DELTA

Implement favorable Government Policies

Investors ! Focus on Value and not cost

Use Modern technology for Acquisition, Processing and

Interpretation.

Target more offshore and onshore fields (both new & mature)

Its not just Oil and Gas, find new opportunities with 4D

CONCLUSION

Considering the Effectiveness of Time-lapse Seismic in few Oil Fields in

Niger Delta, we see that there is a need for its expansion. This is

imperative since we must supply to meet up the high Energy demand for

Oil and Gas.

The Question right now

Shouldn’t be why 4D Seismic ? but Should be why not 4D Seismic?

THANKS !