Exhibit 10.35

SPECIFIC TERMS IN THIS EXHIBIT HAVE BEEN REDACTED BECAUSE CONFIDENTIAL TREATMENT FOR THOSE TERMS HAS BEEN REQUESTED. THE REDACTED MATERIAL HAS BEEN SEPERATELY FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION, AND THE TERMS HAVE BEEN MARKED AT THE APPROPRIATE PLACE WITH TWO ASTERISKS (**).

AMENDMENT  TO NATURAL GAS LIQUIDS PURCHASE AGREEMENT  BY AND BETWEEN  ONEOK HYDROCARBON, L.P. AND MARKWEST OKLAHOMA GAS COMPANY, L.L.C.  DATED AUGUST 25, 2006

This Amendment ("Amendment") is made effective as of November 1, 2008, by and between MARKWEST OKLAHOMA GAS COMPANY, L.L.C.
(formerly known as MarkWest Western Oklahoma Gas Company, L.L.C.) ("MarkWest"), and ONEOK HYDROCARBON, L.P. ("OHLP").

WHEREAS,
under that certain Natural Gas Liquids Purchase Agreement dated August 25, 2006 (the "Agreement"), OHLP purchases and MarkWest sells certain volumes of natural gas
liquids that originate from the Arapaho gas processing plant as described therein; and,

WHEREAS,
said parties desire to amend the Agreement in accordance with Section 21 of the Agreement, as hereinafter set forth.

NOW,
THEREFORE, for good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties mutually agree to amend the Agreement as follows in this
Amendment.

1.Definitions.The following definitions are hereby added to Section 1
of the Agreement as definitions:



2.OHLP's Gathering System.The Expansion to be undertaken by OHLP or its
Affiliate(s) shall be completed and OHLP's gathering system shall be operational by no later than**, absent any circumstances beyond the reasonable
control of OHLP or its Affiliate(s), as the case may be.

3.Term.Section 2 of the Agreement is hereby deleted in its entirety
and replaced with the following:



4.Quantity.Commencing on the Completion Date, the Maximum Production in
Section 3.A is hereby increased to**Barrels per Day,**.

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5.Base and Adjusted Base Differential.Section 6 of the Agreement is
hereby amended as follows:



Product

Base Purchase Differential
¢/Gal.Propane Plus

**Ethane in E/P

**




Product

Base Purchase Differential
¢/Gal.Propane Plus

**Ethane in E/P

**


2

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Year

Total Volume Delivered
(barrels in aggregate)1

**2

**3

**4

**5

**


7.Effect of Amendment.The parties hereto acknowledge and agree that, except
as specifically amended, changed or modified hereby, the Agreement remains in full force and effect in accordance with its terms and that each reference to the Agreement therein shall be deemed to be
a reference to the Agreement after giving effect to this Amendment.

8.Counterparts.This Amendment may be executed in two or more counterparts,
and it shall not be necessary that the signatures of all parties hereto be contained on any one counterpart hereof; each counterpart shall be deemed an original, but all of which together shall
constitute one and the same instrument.

9.Capitalized Terms.Capitalized terms not otherwise defined herein shall
have the respective meanings assigned to such terms by the Agreement.

10.Effective Date.This Amendment shall be effective as of the date first
above written.

MARKWEST:



OHLP:MARKWEST OKLAHOMA GAS COMPANY, L.L.C.

ONEOK HYDROCARBON, L.P.By:  ONEOK HYDROCARBON GP, L.L.C.,
        its General PartnerBy:

/s/ Frank M. Semple

By:

/s/ Sheridan SwordsPrinted Name:

Frank M. Semple

Printed Name:

Sheridan SwordsTitle:

President and CEO

Title:

PresidentDate:

1-7-09

Date:

1/22/2009


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