2. OPERATING REVENUES

Adoption of ASC 606, Revenue from Contracts with Customers

On January 1, 2018, the Company adopted ASC 606 using the modified retrospective approach applied to all contracts as of the date of adoption. Reporting periods beginning after January 1, 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for those periods. The adoption of ASC 606 resulted in offsetting changes to revenues and expenses associated with certain natural gas gathering and processing agreements, and therefore there was no cumulative effect of applying ASC 606 to the opening balance of "Retained earnings (accumulated deficit)." The net impact of adopting ASC 606 for the three and six months ended June 30, 2018 was a decrease of $0.2 million and $0.4 million to "Natural gas" and an offsetting decrease of $0.2 million and $0.4 million to "Gathering and other", respectively, on the unaudited condensed consolidated statements of operations.

These changes result from principal versus agent considerations under ASC 606 for the Company's natural gas gathering and processing arrangements in place with midstream companies. Under contracts where it is determined that control of the natural gas transfers at the wellhead, any fees incurred to gather or process the unprocessed natural gas are a reduction of the sales price of unprocessed natural gas, and therefore revenues from such transactions are presented on a net basis. Under contracts where it is determined that control of the natural gas transfers at the tailgate of the midstream entity's processing plant, the Company is the principal and the midstream entity is the agent in the sale transaction with the third party purchaser of processed commodities. In these instances, revenues are presented on a gross basis for amounts expected to be received from the midstream company or third party purchasers through the gathering and treating process and presented as "Natural gas" or "Natural gas liquids" and any fees incurred to gather or process the natural gas are presented as "Gathering and other."

Revenue Recognition

Revenue is measured based on consideration specified in a contract with a customer and excludes amounts collected on behalf of third parties. Taxes assessed by a governmental authority that are both imposed on and concurrent with a specific revenue-producing transaction that are collected by the Company from a customer are excluded from revenue. Revenues from the sale of crude oil, natural gas and natural gas liquids are recognized, at a point in time, when a performance obligation is satisfied by the transfer of control of the commodity to the customer. Because the Company's performance obligations have been satisfied and an unconditional right to consideration exists as of the balance sheet date, the Company recognized amounts due from contracts with customers of $29.4 million and $24.1 million as of June 30, 2018 and December 31, 2017, respectively, as "Accounts Receivable" on the unaudited condensed consolidated balance sheets.

Substantially all of the Company's revenues are derived from its single basin operations, the Delaware Basin in Pecos, Reeves, Ward and Winkler Counties, Texas. The following table disaggregates the Company's revenues by major source, in order to depict how the nature, timing, and uncertainty of revenue and cash flows are affected by economic factors in the Company's single basin operations, for the periods indicated (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2018		2017(1)		2018		2017(1)
	(Unaudited)				(Unaudited)
Operating revenues:
Oil, natural gas and natural gas liquids sales:
Oil	$	48,756	$	108,695	$	91,825	$	231,216
Natural gas		1,560		5,946		3,879		12,165
Natural gas liquids		4,991		5,306		8,703		11,331

Total oil, natural gas and natural gas liquids sales		55,307		119,947		104,407		254,712
Other		108		190		263		1,023

Total operating revenues	$	55,415	$	120,137	$	104,670	$	255,735


(1)	As noted above, prior period amounts have not been adjusted under the modified retrospective method of adoption.

Oil Sales

The Company generally markets its crude oil production directly to the customer using two methods. Under the first method, crude oil is sold at the wellhead at an index price adjusted for pricing differentials and other deductions. Revenue is recognized at the wellhead, where control of the crude oil transfers to the customer, at the net price received. Under the second method, crude oil is delivered to the customer at a contractual delivery point at which the customer takes custody, title and risk of loss of the product. The Company receives a specified index price from the customer, net of transportation costs and other market-related adjustments. Revenue is recognized when control of the crude oil transfers at the delivery point at the net price received.

Settlement statements for the Company's crude oil production are typically received within the month following the date of production and therefore the amount of production delivered to the customer and the price that will be received for that production are known at the time the revenue is recorded. Payment under the Company's crude oil contracts is typically due on or before the 20th of the month following the delivery month.

Natural Gas and Natural Gas Liquids Sales

The Company evaluates its natural gas gathering and processing arrangements in place with midstream companies to determine when control of the natural gas is transferred. Under contracts where it is determined that control of the natural gas transfers at the wellhead, any fees incurred to gather or process the unprocessed natural gas are treated as a reduction of the sales price of unprocessed natural gas, and therefore revenues from such transactions are presented on a net basis. Under contracts where it is determined that control of the natural gas transfers at the tailgate of the midstream entity's processing plant, revenues are presented on a gross basis for amounts expected to be received from the midstream company or third party purchasers, and therefore any fees incurred to gather or process the natural gas are presented separately as "Gathering and other."

Under certain contracts, the Company may elect to take its residue gas and/or natural gas liquids in-kind at the tailgate of the midstream entity's processing plant. The Company then sells the products to a customer at contractual delivery points at prices based on an index. In these instances, revenues are presented on a gross basis and any fees incurred to gather, process or transport the commodities are presented separately as "Gathering and other."

Settlement statements for the Company's natural gas and natural gas liquids production are typically received 30 days after the date of production and therefore the Company estimates the amount of production delivered to the customer and the price that will be received for that production. Historically, differences between the Company's estimates and the actual revenue received have not been material. Payment under the Company's natural gas gathering and processing contracts is typically due on or before the fifth day of the second month following the delivery month.

Concentrations of Credit Risk

The purchasers of the Company's oil and natural gas production consist primarily of independent marketers, major oil and natural gas companies and gas pipeline companies. Historically, the Company has not experienced any significant losses from uncollectible accounts. For the six months ended June 30, 2018, two individual purchasers of the Company's production, Sunoco, Inc. and Andeavor, formerly Western Refining, Inc., each accounted for more than 10% of total sales, collectively representing 86% of the Company's total sales for the period. In 2017, two individual purchasers of the Company's production, Crestwood Midstream Partners, formerly Arrow Field Services, LLC, and Suncor Energy Marketing, Inc., each accounted for more than 10% of total sales, collectively representing 58% of the Company's total sales for the year.

The Company operates a substantial portion of its oil and natural gas properties. As the operator of a property, the Company makes full payments for costs associated with the property and seeks reimbursement from the other working interest owners in the property for their share of those costs. The Company's joint interest partners consist primarily of independent oil and natural gas producers. If the oil and natural gas exploration and production industry in general was adversely affected, the ability of the Company's joint interest partners to reimburse the Company could be adversely affected.

Practical Expedients

The Company does not disclose the transaction price of unsatisfied performance obligations for i) contracts with an original expected duration of one year or less and ii) contracts where variable consideration is allocated entirely to a wholly unsatisfied performance obligation (each unit of product typically represents a separate performance obligation, and therefore, future volumes under the Company's long-term contracts are wholly unsatisfied).