A higher discount rate decreases the present value of benefit obligations and decreases expense.

The expected rate of return for our retirement benefit plans represents the average rate of return expected to be

earned on plan assets over the period that benefits included in the benefit obligation are expected to be paid. The

expected rate of return for Schlumberger’s United States pension plans has been determined based upon expectations

regarding future rates of return for the investment portfolio, with consideration given to the distribution of investments

by asset class and historical rates of return for each individual asset class. The expected rate of return on plan assets

for the United States pension plans was 7.50% in 2011 and 8.50% in 2010. The weighted average expected rate of return

on plan assets for the international plans was 7.50% in 2011 and 8.00% in 2010. A lower expected rate of return would

increase pension expense.

Schlumberger’s medical cost trend rate assumptions are developed based on historical cost data, the near-term

outlook and an assessment of likely long-term trends. The overall medical cost trend rate assumption utilized to

determine both the 2011 postretirement medical expense as well as the postretirement medical liability as of

December 31, 2011 was 8% graded to 5% over the next six years.

The following illustrates the sensitivity to changes in certain assumptions, holding all other assumptions constant,

for the United States and international pension plans:

25 basis point decrease in discount rate

+$32

+$299

25 basis point increase in discount rate

-$28

- $283

25 basis point decrease in expected return on plan assets

+$15

–

25 basis point increase in expected return on plan assets

-$15

–

The following illustrates the sensitivity to changes in certain assumptions, holding all other assumptions constant,

for Schlumberger’s United States postretirement medical plans:

25 basis point decrease in discount rate

+ $4

+ $44

25 basis point increase in discount rate

- $4

- $41

100 basis point decrease per annum in medical cost trend rate

- $24

- $160

100 basis point increase per annum in medical cost trend rate

+ $28

+ $196

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