Study On Production Prediction For Horizontal Wells

At present the technique of horizontal well production has been used widely in oil fields, and has been an important treatment to both develop new oil fields and improve the oil recovery. To obtain high oil production rate and economical benefit it is very important to evaluate the oil productivity of horizontal wells correctly. There are many methods to predict the horizontal wells' oil productivity, but most of them adopted analytical methods, which includes many supposed conditions. And many parameters in the analytical formula are difficult to be presented. These methods possess many limitations. In allusion to the limitations new methods to predict the horizontal wells' oil productivity are studied in this paper. We get the following research results. (1) Centered on the economic profit, a calculation method is brought forward which can calculate the ultimate cumulative oil production rate, the initial oil production rate and other parameters' limitation. This study has provided facility and reference for reservoirs to develop with horizontal wells. (2) Based on the parameters of horizontal wells that have been put into production, we use the Grey Interconnect Analysis to sort the parameters that have great effect on horizontal wells according to their importance. This method and result have instructive function on designing horizontal wells. (3) By using imaging and super-position principle this paper studied the calculating formulae of horizontal well. By revising the calculating formulae the prediction precision is improved. (4) The method of fuzzy clustering analysis is introduced into the filtration and estimate of horizontal well. Based on the known data of horizontal wells that have been put into production, those wells can be classified into several groups using the method of fuzzy clustering. Then the new designed well is sorted into one of those groups according to its character. The new well can be evaluated by using the production index of the wells in the same group. (5) Based on the characters of positive cyclothem reservoir formation of fluvial facies a conceptive model is founded. Using the technique of reservoir simulation the prediction formulas of bottom-water drive reservoir are obtained. (6) Based on the mechanism of water coning of horizontal wells in bottom-water drive reservoir the critical production pressure difference is obtained. This study enriched the methods of horizontal wells' oil production prediction and provided a new filtration and evaluation method to develop oil fields by horizontal wells.