Sand Deposition Inside a Horizontal Well-A Simulation Approach

Abstract

Horizontal wells have been shown to be successful in improving oil recovery for marginal heavy oil reservoirs in Saskatchewan and Alberta. One commonly encountered problem in recovery operations for these poorly consolidated reservoirs is the production of sand and fines into the horizontal wellbore, where they settle and accumulate. This paper reports the numerical modeling of gravitational deposition of sand in a horizontal well in such heavy oil reservoirs. The numerical model described in this work examines the transport process mechanistically, based on the conservation equations for the fluid phase (heavy oil) and the solid phase (sand particles). The interaction between these phases is described by empirical correlations. The equations are solved numerically to determine the concentration of sand particles and oil, and their respective pressure and velocity distributions inside the horizontal well. According to the simulation results, oil viscosity and particle size play important roles in the transport process, including controlling the gravitational settling tendency of solid particles inside the horizontal wellbore. The results provide insight into the roles different mechanisms affect the transport of sand particles; as such, they provide guidelines for production operations involving horizontal wells in poorly consolidated and unconsolidated reservoirs. Introduction The use of horizontal wells, in Saskatchewan and Alberta heavy oil reservoirs underlain with bottom-water, has been found to improve primary recovery performance prior to water coning-recovering up to 15%, in some cases, of the initial oil in place, compared with only 5% for a vertical well(1). Horizontal wells have also been successfully used for increasing steamflood recovery(2,3). Due to the unconsolidated or poorly consolidated nature of these reservoirs, solid (sand and fines) production is quite prevalent. The produced solids lead to several production problems, including sand filling up the wellbore, preventing the operation of downhole pumps and surface equipment, etc.(4) In horizontal well cases, sand production potentially poses a serious problem, as the sand could settle and accumulate inside the horizontal wellbore. This settlement and accumulation of sand particles could give rise to reduced cross-sectional areas of the wellbore open to flow. The study reported in this paper examines, using numerical simulation, the gravitational deposition of sand particles inside a horizontal wellbore. A brief survey of the relevant literature is given in the following. Solid-liquid multiphase flows are usually very complex, due to the large number of variables involved in the transport processes, and typically poorly understood interaction between the variables. There have been many experimental investigations of these (and other) flow processes, particularly focused on the deposition of the solid particles. Many of the earliest investigations of solid liquid flows focused on the settling tendency of solid particles. Richardson and Zaki(5) experimentally determined that the falling velocity of a suspension relative to a horizontal plane was equal to the upward velocity of the fluid required to maintain a suspension at the same concentration. For different flow regimes (i.e., Reynolds numbers), separate correlations were developed (from experimental data) for the exponent which corresponds to the slope of log-log plot straight lines between suspension falling velocities and suspension porosities.

Modeling of Sand and Crude Oil Flow in Horizontal Pipes during Crude Oil Transportation

“…The Doan et al [1,11] models were developed for the case of sand and oil flow in an oil well and this informed why they were chosen from the reviewed models for application, other reasons being the inclusion of parameters such as sand and crude oil concentration terms, solid and liquid phase pressures, solid and liquid densities, liquid and solid interaction forces, kinematic pressure, liquid and solid concentrations, solid and liquid velocities, and liquid viscosity among others. The model represented by (1)-(4) was subsequently modified by assuming that all other components (asphaltenes, resins, and olefins) were dissolved in the oil at the flow conditions while taking effect of eddies into account.…”

“…The new model as compared to the Doan et al [1,11] models shows that (11) is an additional equation for solid phase while (13) is the modified form of (3) because it includes a total sand concentration term, that is, Ψ.…”

“…At the head of the wells, horizontal transmission lines with or without screens transport the residual sand in the oil from feeder lines to flow stations. The entrained sand may deposit on the walls of the pipe due to pressure drop causing problems such as abrasion, corrosion, pipe blockage, reduction in flow area, loss in pipe integrity, and most importantly low output from the lines [1]. Sand exclusion measures (sand screens, sand filters, and gravel packs) used hitherto are somewhat laborious and expensive [2]; hence, it is necessary to search for an alternative solution to the problem such as using a mathematical model.…”

“…Doan et al [1] model represents a simulation approach of sand deposition inside a horizontal well. Although the model includes channel height, it can also account for the effect of oil viscosity and particle size on the transport process.…”

In Mergers and Acquisitions—IT: Results of the Absence of CIO in Ex-ante Planning and the Absence of Key IT Staff in Ex-post Integration

“…24 Within the next year, The Learning Company reported losses of $206 million, causing Mattel's bottom line to plummet right alongside it, creating a business-wide loss of $88 million. 25 By 2000, Mattel was suffering losses of $1.5 million per day and a continually falling stock price. Less than two years after the purchase, Mattel sold off its acquisition but not before being forced to lay off ten percent of its workforce to cut costs.…”