Thermally-reduced oil formation volume factor is correlated with solution gas-oil ratio from 0 to 3,500 cu ft/bbl. This correlation was made from the differential liberation curves of 159 analyses of saturated Eastern Venezuelan crudes. Average error, determined by comparing correlation and calculated with the laboratory-determined oil formation volume factor, was found to be 2.00 per cent. Average error of 104 separator flash tests was 1.97 per cent. Introduction Based on the original method of Katz, a correlation of thermally-reduced oil formation volume factor and solution gas-oil ratio has been made from saturated Eastern Venezuelan crudes. The accuracy of this correlation, which requires a minimum amount of data and is easy to use, is sufficient for most reserves estimates. The average correlation error of 2.00 per cent for reservoir differential data compares closely with the 1.97 per cent error for separator flash data. While the accuracy of this correlation for other oil-producing areas is not known, there is close agreement with the general correlation of Katz. Also, there is a wide crude-oil gravity range represented, 15 degrees to 47.5 degrees API, with reservoir temperatures that range from 142 degrees to 307 degrees F. It is thought, therefore, that this correlation can be universally applied with reasonable accuracy. Wherever sufficient data exist, a cross plot can quite easily be made so that an area-oriented correlation is obtained. Construction and Error Fig. 1 is a correlation obtained from 159 differential liberation curves of saturated Eastern Venezuelan crudes. This correlation closely parallels the Katz general correlation previously made to a maximum solution ratio of 1,300 cu ft/bbl. Data obtained from volatile Venezuelan crudes shows that this correlation can be extended to 3,500 cu ft/bbl with good data conformance. The extension of the correlation is almost linear. Data used in Fig. 1 represent crude oils which range from 15 degrees to 47.5 degrees API. Reservoir temperatures of these crudes range from 142 degrees to 307 degrees F.

Gas-oil rekuive pernzeability ratio is an intportant relationship in oil reservoir prec7ictive calculations. A correlation has been developed jronz 107 gas-flood k, ,,/k ,,, tests on Venezuelan core .wnples, The correlating parameter is based on restored-state water saturatiotr'tests and is applicable to both consolidated and poorly consolidated sandstone reservoirs. Data of the correlation show that thereare 120 distinguishable differences between the mass-data groupittgv @ the two claiiificatiom. A procedure is recommended for running snficient relarit'e permeability attdyse.r to compute o geotnetric mean of the sample group. The geotnetric mean is more representative of the total cwe, ancl probably' the entire rc~smmir. For example, witile only otte in four of the k,,,/k,,, test curves agreed closely with the resultant correlation of this report, the geometric matt curves Of the 16 .wites (three samples or more) shw'ed good agrcetnent in rhrce cases out of four.."-.

CHARLES R. KNOPP JUNIOR MEMBER AIMEWater encroachment into low gravity oil reservoirs tends to be irregular because of three mechanisms -(I) selective encroachment, (2) water-leg tonguing and (3) individual well coning.An investigation was made of 31 wells that were completed in low gravity oil sands with bottom water present in the base of the well-sand interval. It was found that initial water cuts occurred rapidly. Current average recovery for each of the 31 original completions is 10,184 bbl (31 per cent) clean oil and 22,542 (69 per cent) wet oil. Fourteen (45 per cent) of the 31 original completions have either been recompleted to other sands or are not feasible to produce because of high water-cut production. Average cumu:lative recovery for each original completion is now only 32,726 bbl of oil.Four low gravity oil reservoirs with well defined fault boundaries and original oil-water contacts were studied to ascertain the effects of irregular edge-water encroachment. This study showed that initial water cuts have rapidly occurred in all 12 (including the most up-dip) wells completed in the four reservoirs; only two of these wells were completed with an original water-leg extension in the base of the well-sand interval. Comparative clean and wet oil recovery from these four reservoirs has been 419,100 bbl (34 per cent) clean oil vs 810,500 bbl (66 per cent) wet oil.Ultimate recovery from the abandoned MG-30 reservoir is 1.9 per cent of the 8 million STB of oil initially in place. It is concluded that selective encroachment of edge water along thin, highly permeable, stratum has acted to reduce ultimate recoveries in the four reservoirs from 7 per cent -the recovery that would be expected if solution gas drive were the depletion mechanism.Two basic remedial techniques offer a possible solution for eliminating adverse (irregular) edge-water encroachment. One of these is gas pressure maintenance. The second technique embodies the production of water from the more down-dip areas of the reservoir to balance water influx from the associated aquifer.