HOUSTON OIL <HO> RESERVES STUDY COMPLETED Houston Oil Trust said that independent petroleum engineers completed an annual study that estimates the trust's future net revenues from total proved reserves at 88 mln dlrs and its discounted present value of the reserves at 64 mln dlrs. Based on the estimate, the trust said there may be no money available for cash distributions to unitholders for the remainder of the year. It said the estimates reflect a decrease of about 44 pct in net reserve revenues and 39 pct in discounted present value compared with the study made in 1985.