LONDON, Sept 12 (Reuters) -North Sea Forties and Ekofisk crude differentials rose on Thursday due to higher bids, while U.S. WTI Midland crude was steady after a lack of pricing indications.

PLATTS WINDOW

* Indications are on a free-on-board (FOB) basis unless marked as cost, insurance and freight (CIF) or delivered at place (DAP).

* No deals, a trade source said.

* Ekofisk: Gunvor bid Sept. 28-30 at dated Brent plus $2.60 and Shell offered Oct. 2-4 at dated Brent plus $2.45. Those were both above the last offer which was at dated plus $2.35.

* Ekofisk: Allowing for the Platts quality premiums for the two loading months, those indications value Ekofisk at dated Brent plus $1.39 for dated Brent purposes, according to Reuters calculations.

* Forties: There were two bids at dated Brent plus $1.15. up from the last assessment.

* WTI Midland: No pricing indications. Last valued at dated Brent plus $2.30 CIF Rotterdam, or around dated plus $1.43 on a FOB basis according to Reuters calculations.

* Forties therefore becomes the cheapest grade underpinning the benchmark.

Reporting by Alex Lawler, Editing by Susan Fenton

 NORTH SEA CRUDE OIL DIFFERENTIALS AND OUTRIGHT PRICES: 0#BFO-DIF 0#C-E Dated BFO BFO- Brent BFO-BRT BFO-E Forties BFO-FOT FOT-E Oseberg BFO-OSE OSE-E Ekofisk BFO-EKO EKO-E Monthly North Sea crude loading programmes O/LOAD OPEC OPEC NSEA North Sea CRU crude oil PROD oil products DRV derivatives PRO/E European products OILOIL NYMOIL, IPEOIL, OILSPD, OILARB CRDWLDPRODEUR, PRODUS, APROD ENERGY energy speed guide CRUDE/1 crude speed guide