Exhibit 15
JOINT FILING AGREEMENT
We, the undersigned, hereby express our agreement that the attached Schedule 13D/A is filed on behalf of each of us pursuant to and in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.
| Date: July 18, 2018 | DEVON ENERGY CORPORATION | |||||
| By: | /s/ Jeffrey L. Ritenour | |||||
| Name: | Jeffrey L. Ritenour | |||||
| Title: | Executive Vice President and Chief Financial Officer | |||||
| DEVON ENERGY CORPORATION (OKLAHOMA) | ||||||
| By: | /s/ Jeffrey L. Ritenour | |||||
| Name: | Jeffrey L. Ritenour | |||||
| Title: | Executive Vice President | |||||
| DEVON GAS CO., L.L.C. | ||||||
| By: | /s/ Jeffrey L. Ritenour | |||||
| Name: | Jeffrey L. Ritenour | |||||
| Title: | Executive Vice President | |||||
| SOUTHWESTERN GAS PIPELINE, L.L.C. | ||||||
| By: | /s/ Jeffrey L. Ritenour | |||||
| Name: | Jeffrey L. Ritenour | |||||
| Title: | Executive Vice President | |||||
| DEVON GAS OPERATING, INC. | ||||||
| By: | /s/ Jeffrey L. Ritenour | |||||
| Name: | Jeffrey L. Ritenour | |||||
| Title: | Executive Vice President | |||||
| DEVON GAS SERVICES, L.P. | ||||||
| By: | /s/ Jeffrey L. Ritenour | |||||
| Name: | Jeffrey L. Ritenour | |||||
| Title: | Executive Vice President | |||||
JOINT FILING AGREEMENT