I do not know which interlinear you used, but Green's says in verse 26: "Jehovah" [YHWH]. Berry's is the same. Verse 26 specifically says, "Jehovah." Kholenberger et all. have the same, but use Yahweh. So the Lord to whom Abraham refers is Jehovah.
That established, 1 Cor. 8:5 observes that there are many called God and many called Lord. Being called Lord does not mean that one is the same person as someone else called lord. There is not valid trinitarian argument here.
The Hebrew word 'adouneem' is a title given to men holding authority. In Gen 18-19 we find 'Baaleem.' That's a term applied to owners and masters. God is, of course, the ultimate owner or master of all. But the term was applied to men, pagan gods, and Jehovah. [See Pick's Dictionary of Old Testament Words; and The Theological Dictionary of the Old Testament.] The word Lord as applied to Jesus is κύριος [Kyrios]. It has a similar meaning. Vine defines it as "signifying having power or authority" when used as an adjective [i.e.: the lord Christ Jesus].
Vine further observes that the word is "equally appropriate to either [Jesus or God.]" He cites many examples which when consulted differentiate between God and Christ. In fairness I should note that Vine was trinitarian.
If you intend to follow up at some depth, I see the Insight book as helpful in this case. But you will also want to visit Lang's Commentary; Robertson's Word Pictures in the New Testament; Vincent's Word Studies; and Wuest's Word Studies. These are all trinitarian, but will help you understand the usage of the words involved here.