Quad Neutron Measurement – Seligi Experience - platinum

Quad Neutron Logging – Seligi Experience;Division – EQ Petroleum Development MalaysiaW A Manan ©Petroliam Nasional Berhad (PETRONAS) 2014 1

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Quad Neutron Measurement –Seligi Experience

EQ Petroleum Developments, Sdn. Bhd

Presenter: W A Manan


• Introduction

• Concept of the technology

• Effect of reservoir fluids on the measurement

• Quad Neutron Log output

• Interpretation

• Log examples

• Application of the technology

• Limitations

Agenda:


Low salinity formation water, deep borehole fluid invasion in high water cut wells,oil smeared into gas zones and cross flow between reservoirs pose problems influid contacts monitoring in Seligi Field using conventional pulsed neutron loggingtools.

Introduction.

Structural Cross-Section – Tinggi to Seligi Central & South Culminations

A A’

L-10

GH

B

E

TINGGI

A

DCF

A’

A

Location Map


Thru pipe thermal neutron and gamma activation measurement and compensation are used, to overcame limitations in conventional pulse neutron technology in measuring reservoir properties (PHIT, Sw, Fluid Type). Porosity are estimated using different 4 different approaches and the differences between them are used, using overlay technique to identify fluid type and oil saturation, Oil/Water differentiation is less sensitive to formation water salinity.

Concept of the technology:Quad Neutron Logging


Effect of Oil Api and Salinity on NN & NG.


i. Porosity:

Calculate porosity using 4 different approaches

•

•

•

•

Quad Neutron Log Output.


Quad Neutron Log output :

ii. Relative Bulk Density (CE)

Calculated from NN and NG interaction of long and short spacing - and used to correct QL

for saturation calculation and gas flagging

iii. Quad Clay – is based on Gr emitted by Aluminium as result of Neutron activation in the measured

volume. Is used to calculate VSH, Effective porosity

iv. Saturation – Calculated from overlay between QTP and QL

Quad Neutron Log Output.


Fluid Types identification

Utilize overlay technique and different sensitivities of computed porosity to identify fluid types.


Validation of Roke (Perforating): Se-D21, K20


Validation of Roke (Consistency)


Important: Integration with other information is important in cased hole log interpretation to avoid error in the interpretation

Well integrity – Cross flow behind casing, additional information to reservoir management.


Important: To provide all the relevant well information: correct completion

diagram and reservoir fluid properties to avoid error in the

interpretation.

reservoir information

Processing input parameters


The Results

•

•

•

•

Applications of the technology


• Annulus between the tool and tubing/casing must be liquid field.

• Depth of investigation is between 2 to 3 ft. In deep borehole fluid invasion.

i.e., high water cut wells, readings will be affected by invading borehole fluid.

• Erratic readings in poor quality rocks, occasionally indicate oil in shale.

• Good for Qualitative interpretation, OWC and GWC. Probably large error in So

estimation.

• Affected by borehole quality: poor cement quality, large washout complicate borehole correction calculation.

• Fluid properties (water salinity and oil API) affect the interpretation. Logging objectives and reservoir fluid information need to be provided during planning

stage.

Limitations


Thank you

Quad Neutron Measurement – Seligi Experience - platinum

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