Determination of bottomhole pressure by using multivariate statistical models (on example of formation TL-BB Yurchukskoie field)

Abstract

The problem of determining BHP in production wells not equipped with depth measuring systems, it is relevant for many of the oil fields of Perm Krai. In practice, the absence of special devices for downhole pump bottomhole pressure is determined by converting the dynamic level. With this approach, the main difficulty is the calculation of the density of the gas-liquid mixture, the accuracy of which is low due to the influence of numerous complicating factors. In this paper the fundamentally different approach to the definition of bottomhole pressure, considered on one of the well equipped with high-precision depth measurement system, of Tl-Bb layer of Yurchukskoe field. The initial data are direct measurements of downhole pressure, as well as a number of other indicators of its operation (flow rates of oil and liquid, water content, dynamic level, the pump depth below the dynamic level, the pressure of the annulus). The first stage analysis of the data led to the conclusion that the bottomhole pressure during the observation period varied, with different directions: the first is gradually reduced, then - increased. In this regard, the study of influence of operating parameters on the value of BHP held for three cases: for the entire period of observation, as well as separately for the period of its decline and the increase. Statistical analysis of the averages and distribution densities possible to identify the parameters that influence the bottomhole pressure, and found that the effect is mixed. At the final stage the multidimensional statistical models that take into account the effect of multidirectional operating indicators BHP have been built. "Functionality" verification of developed models was made on the example of three other wells of the same development object. This verification confirmed the feasibility of using developed models for determining the values of bottomhole pressure from known values of indicators for well operation and all the proposed approach in general.

Keywords

• well operation indicators
• bottomhole pressure
• mechanized wells
• unequipped depth measuring systems
• method of determining bottomhole pressure
• statistical analysis
• factors affecting the value of bottomhole pressure; correlation
• stepwise linear discriminant analysis
• linear discriminant function
• multidimensional mathematical model
• different directions of influence factors
• regression analysis
• multiple regression
• models functionality