Surprises may be in store this earnings season for U.S. companies tied to BP Plc's oil spill, according to an analysis that emphasizes equity analysts' past accuracy.

Among companies likely to surprise with lower-than-expected earnings in the upcoming reporting period is Schlumberger Ltd, according to forecasts from StarMine.

There is a spillover effect into some of these companies that we see happening this quarter, and some analysts think it might actually go into the next couple of quarters, said Sri Raman, senior quantitative research analyst at Thomson Reuters.

StarMine, which weights forecasts according to analyst accuracy, estimates 66 cents a share for Schlumberger, compared with a Thomson Reuters consensus estimate of 68 cents.

The world's largest oilfield services company had performed wireline services for BP on the rig in the Gulf of Mexico where the April 20 explosion and spill occurred.

Schlumberger, expected to report quarterly results later this month, is among five singled out by StarMine before the reporting period to show negative surprises.

The second-quarter earnings period begins with results from Alcoa after the bell on Monday.

Earnings for the Standard & Poor's 500 as a whole are expected to increase about 27 percent from a year ago, according to Thomson Reuters. Forward 12-month earnings projections have slipped by 0.4 percent in the last 30 days, according to StarMine.

Among companies seen as most likely to surprise with higher-than-expected earnings is oil and natural gas explorer Brigham Exploration Company, which focuses on non-offshore work. StarMine's estimate is for earnings of 9 cents a share, above the consensus estimate of 8 cents a share. It is expected to report results in August.

Clean Harbors, involved in clean-up operations related to the spill, also is expected to beat the consensus estimate. StarMine's estimate is for earnings of 85 cents compared with the consensus estimate of 80 cents a share.

Anadarko Petroleum Co, which is a minority leaseholder in the destroyed BP rig, is expected to earn 41.1 cents a share, which would exceed the Thomson Reuters consensus by 5.5 percent.

Four companies StarMine noted as likely to surprise to the downside with earnings were DreamWorks Animation, Gaylord Entertainment Co, Regal Entertainment Group and Dendreon Corp.

StarMine's other top picks for companies likely to beat consensus earnings estimates are Walt Disney Co, which StarMine forecasts to exceed the overall consensus by 2.5 percent. Paccar Inc and AmerisourceBergen Corp are also expected to exceed results.

For a Reuters Insider program on the StarMine estimates, please see

(Reporting by Caroline Valetkevitch; Editing by Kenneth Barry)