Oil, Water And Sand Flow Experiments In a Model H(Jlrizont~d Well

Abstract

Abstract An experimental investigation has been conducted using a 52 mm laboratory test loop incorporating a section of pipe with longitudinal well slots. Single phase flows with radial and axial flow confirmed the validity of a one dimensional model in predicting pressure gradients for both laminar and turbulent flow. No additional turbulence resulting from the influx could be detected. Experiments using an oilfield sand of median diameter 0.22 mm and either produced water or an oil of viscosity 66 mPa.s showed that there was a threshold velocity for sand transport to occur. Stationary deposits of sand were present at velocities well above the threshold velocity. For sand transport in turbulent flow, the Meyer-Peter equation predicted transport rates as functions of water velocity fairly well at low velocities. The laminar flow pressure drop and sand transport results were quite different from the turbulent flow results. They were also different far the two oils; in neither case was a homogeneous flow model found to be appropriate. For flow with stationary sand deposit, radial influx appeared to reduce axial pressure gradients when the sand in the deposit was fluidized by the influx. Injection of water into the heavy oil containing sand showed that some of the sand was washed out of the oil by the water. The water appeared to migrate to form bubbles near the axis of the pipe, leaving the wall oil-wet. High water cuts and low pressure gradients resulted from water injection. Introduction Although horizontal well were first used more than 50 years ago, they were impractical before the recent developments in drilling and completion had taken place. The number of horizontal well in Saskatchewan has increased markedly, so that it appears they will become the standard production technique by the end of the century. In an attempt to contribute to the application of the method to the heavy oil reservoirs of Western Canada. a five-year multidisciplinary study of the reservoir engineering aspects of horizontal wells has been undertaken by the Saskatchewan Research Council. The project was initiated in 1990 with support from several producing companies and agencies of the governments of Canada. Alberta and Saskatchewan. The research reported herein Consists of a first attempt to examine the flow in a horizontal well in conditions likely to be of interest in reservoir modelling. In order for fluid to flow in a horizontal well there must be a pressure decrease in the downstream direction. If the velocity in the wellhore is very low this pressure gradient may be negligible compared to the pressure difference between tile reservoir and the well. However with thin reservoir and underlying water this may not be the case. The effect of the axial pressure gradient On production was predicted theoretically by Dikken (1990) using a homogeneous fluid model and assuming smooth pipe flow in the wellbore. The complication of multiphase wellbore now were recognized by Stone el al. (1989) who adapted the well-known steam water model RELAP5/MODI (Ranson et al 1982) to the case of flow in a horizontal well.