Drainage Area for Horizontal Wells With Pressure Drop in the Horizontal Section N.F. Saavedra; N.F. Saavedra Ecopetrol Search for other works by this author on: This Site Google Scholar D.A. Reyes D.A. Reyes DTH LTDA Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Buenos Aires, Argentina, March 2001. Paper Number: SPE-69431-MS https://doi.org/10.2118/69431-MS Published: March 25 2001 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Saavedra, N.F., and D.A. Reyes. "Drainage Area for Horizontal Wells With Pressure Drop in the Horizontal Section." Paper presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Buenos Aires, Argentina, March 2001. doi: https://doi.org/10.2118/69431-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Latin America and Caribbean Petroleum Engineering Conference Search Advanced Search AbstractIn general, a horizontal well is more productive than a vertical well, due to the fact that there is a larger area of contact with the reservoir and that there is less pressure drop per unit of length in the production section.The two main factors to obtain more reserves in a reservoir are the increase in drainage area or an increase of the recovery factor using some enhanced recovery method.The productivity as well as the drainage area of a horizontal well may be limited by the pressure drop within the wellbore, especially when the pressure drop is comparable to the drawdown from the reservoir to the wellbore. Over the past few years, horizontal well technology has acquired quite significant importance and thousands of wells are drilled around the world every year, which is why there is a need for more information on the factors that affect pressure drop within the well.Total pressure drop in horizontal wells has been analyzed in terms of four separate effects: wall friction, flow acceleration, perforation roughness, and fluid mixing.1 Thus, the pressure drop in horizontal wells is made up of a gravity term, a frictional term and another due to flow acceleration.2The literature available about calculating drainage areas of horizontal wells only covers geometric methods, which assume that the horizontal well drains an elliptic area or a combined area made up of a central rectangle and two semi-circles on the ends.2,3This paper proposes an expression to calculate the drainage area of horizontal oil wells that produce at high reservoir flow rates, exhibiting a frictional pressure drop throughout the wellbore between 15 to 60% of the reservoir drawdown at the heel of the well.IntroductionOne of the advantages of horizontal wells over vertical wells is the increase in the area of contact with the reservoir, where less pressure drawdowns are required to produce at the same rate as a vertical well,4 thus reducing the possibility of problems such as coning (cresting), the precipitation of scales and the production of sands, among others.One of the variables required in the production forecast of a horizontal well is drainage area.The methods proposed by Joshi and Borisov, for wells with horizontal sections open to the flow, are based on areas of symmetric geometry3 and do not consider the effect of pressure losses along the production section.Being aware of the effects of pressure drops on horizontal wells is crucial to calculate the drainage area including friction effects and therefore, for the optimization of its production behavior.In the case of long wells or high flow rates, the pressure drop through the well may be comparable to the reservoir drawdown at the producing end of the well. A Portion of the well downhole would then be unproductive because the local drawdown there is small or even zero9. Researchers have tried to identify the situations where loss of drawdown along a horizontal well reduces productivity and to quantify the effects of friction in a horizontal wellbore.Dikken4 proposed a model in which a steady state turbulent flow is considered in a single phase. The traditional friction factor for flow in tubes links the pressure gradient within the well and the local flow velocity. Dikken describes flow in the reservoir with a specific Productivity Index, which must be independent of position along the well. A Volume balance across the well boundary then leads to a differential equation that can be solved for the profile of flow rate along the wellbore.Novy9, proposed a study in which he reports the guidelines that indicate the cases where friction should be considered in a particular reservoir/well system.This article discusses an expression to calculate the drainage area of a horizontal well considering the effects of the pressure drop profile due to friction along the production section of the well. It is proposed that the drainage area for horizontal wells with a frictional pressure drop throughout the wellbore between 15 to 60 % of the reservoir drawdown at the heel of the well be evaluated, assuming that the well affects an area composed of the sum of three different surfaces. Keywords: horizontal length, production control, production section, upstream oil & gas, flow rate, frictional pressure drop, pressure loss, production monitoring, directional drilling, spe 69431 Subjects: Drilling Operations, Well & Reservoir Surveillance and Monitoring, Formation Evaluation & Management, Directional drilling This content is only available via PDF. 2001. Society of Petroleum Engineers You can access this article if you purchase or spend a download.