Calculation Method for Bottomhole Flow Pressure in Co-layer Development of Multilayer Sandstone Reservoir

Abstract Accurately calculating the bottom hole flow pressure of a multi-layer stacked sandstone reservoir (hereinafter referred to as a multi-layer reservoir) is the basis for production splitting, oil well dynamic analysis, and reasonable work system determination in the development of multi-layer reservoirs. The bottomhole flow pressure model for single-layer oil reservoirs does not consider interlayer interference and the pressure drop caused by fluid flow in the wellbore, which doesn’t comply with the characteristics of multi-layer combined production, and the use of the maximum bottomhole flow pressure of the oil layer as the bottomhole flow pressure of each oil layer to adjust the production system of each oil layer doesn’t meet the requirements of other oil layer regulation. Firstly, starting from fluid mechanics, the frictional effect generated by fluid flow in the wellbore is systematically considered, and the relationship between wellbore frictional pressure drop and flow distance is established. The pressure drop formula generated by fluid flow in the wellbore is derived; Secondly, from the perspective of seepage mechanics, a formula for the bottom hole flow pressure of a single-layer reservoir was obtained. Combined with the expression for the difference in bottom hole flow pressure of each oil layer in the development of a multi-layer reservoir and the pressure drop expression for fluid flow in the wellbore, a bottom hole flow pressure model for each oil layer in the development of a multi-layer reservoir was established (hereinafter referred to as the multi-layer reservoir bottom hole flow pressure model). Substitute various parameters into the bottomhole flow pressure model of multi-layer oil reservoirs, and the error between the calculated values and the actual test values in the field is 0.10%~1.30%, with an average error of 0.82%, meeting the actual needs of the site. There is a significant difference in the bottom hole flow pressure values of each oil layer in the co production reservoir. The multi layer reservoir bottom hole flow pressure model can accurately calculate the bottom hole flow pressure of each oil layer, avoiding the inability to accurately adjust the production system of multiple oil layers for the same bottom hole flow pressure. It can provide technical support for the development of a reasonable drainage system for on-site co production oil wells and the realization of high and stable production.