Varco International, an Orange-based maker of tools and equipment for the oil industry, reported a net loss of $6 million for 1987, compared to a net loss of $9.2 million in 1986. Revenues declined 11% for the year to $37.8 million, from $42.5 million. For the fourth quarter of 1987, Varco had net earnings of $99,000--the company's first profitable period since the first quarter of 1986--compared to a loss of $2.6 million for the year-earlier period. Revenues for the fourth quarter increased 93% to $13.3 million, from $6.9 million. Varco Chairman W.B. Reinhold said an improved oil drilling industry and a reduction in costs contributed to the fourth-quarter performance.