Oil group SOCO International has gushed higher after it said the second phase of development has begun on the Ca Ngu Vang oil and gas field, offshore Vietnam.The first well in the programme, CNV-6P-ST1, is expected to take around 60 days to drill.Oil-related stocks in general are boosted by strong crude prices, which are sitting near 17-month highs.Wellstream, which designs and manufactures flexible risers and flowlines for the oil and gas industry, is also higher as is oil and gas group JKX.Not all oil stocks are strong though, with oil and gas explorer Melrose Resources in the red. FTSE 250 - RisersGem Diamonds (GEMD) 280.10p +9.84%Soco International (SIA) 1,770.00p +5.42%Connaught (CNT) 267.00p +5.33%Trinity Mirror (TNI) 157.70p +4.71%Talvivaara Mining Company (TALV) 483.00p +4.30%Hargreaves Lansdown (HL.) 343.90p +4.21%Wellstream Holdings (WSM) 687.00p +4.09%Chloride Group (CHLD) 223.40p +3.91%Fenner (FENR) 224.20p +3.89%JKX Oil & Gas (JKX) 293.40p +3.82%FTSE 250 - FallersHansteen Holdings (HSTN) 79.00p -2.47%Grainger (GRI) 133.50p -2.27%Misys (MSY) 243.20p -2.05%Melrose Resources (MRS) 303.80p -2.00%De La Rue (DLAR) 921.50p -1.97%Cranswick (CWK) 796.00p -1.85%Rathbone Brothers (RAT) 861.50p -1.82%Drax Group (DRX) 371.40p -1.75%Brewin Dolphin (BRW) 144.10p -1.64%Northumbrian Water Group (NWG) 286.70p -1.58%