Effect Of Flow In Horizontal Wellbore On Productivity

Most of the productivity prediction models of horizontal well were established onthe basis of the assumption of infinite conductivity in horizontal wellbore. However, inthe actual production process, the pressure drop is existed when the fluid flows inhorizontal wellbore from toe to heel. The flow in horizontal wellbore is the massvariable flow because the fluid inflows from the wall on the horizontal productiondirection continuously. The pressure drop is existed in the horizontal wellbore from thetoe to the heel. In some case, the pressure drop in the horizontal wellbore may equal tothe producing pressure drop. In this situation, using the normal steady andpseudo-steady productivity prediction model of horizontal well to predict the horizontalwell productivity may cause some inaccuracy. In the process of horizontal wellproduction, flowing in the horizontal wellbore, inflowing from the wall and thereservoir are a uniform hydrodynamic system. So the pressure drop in horizontalwellbore must be considered in horizontal productivity prediction.In this paper, the steady and pseudo-steady productivity models of horizontal wellin different reservoir types are concluded. The productivity prediction models ofhorizontal wells are established coupling the flow in the horizontal wellbore and fluidflow in the reservoir. The model is established considering the effect of flowing inhorizontal wellbore, inflowing from the wall and the seepage in stratum. The factorswhich affect the productivity prediction of horizontal well are determined by calculatingthe coupling model with actual production data. The mainly contents and conclusions ofthis paper are as follows:1. The steady and pseudo-steady productivity prediction models of horizontal wellin different reservoir types are concluded and evaluated.2. The pressure drop model of horizontal well mass variable flow is establishedusing continuity equation and momentum conservation equation, and the relativeapparent friction factor is presented.3. The productivity prediction model of horizontal well is established coupling theflow in the horizontal wellbore and fluid flow in the reservoir. The effect of flowing inhorizontal wellbore, inflowing from the wall and the seepage in stratum are consideredin this model. The method for solving this model is presented.4. The sensibility analysis of these factors which influence the calculation ofhorizontal well under the condition of steady flow are carried out.