Sand Control in Horizontal Wells in Heavy Oil Reservoirs

Abstract

Abstract Horizontal wells are of great interest to most oil companies operating inheavy oil fields. Due to more extensive contact with the reservoir, horizontalwells allow fluid flow at lower fluid velocities yet providing total flowswhich are economic. While horizontal wells have the potential to make many moreheavy oil reservoirs economic, one of the most pressing concerns has been to beable to complete the wells properly. Unfortunately, likely candidates ofhorizontal wells are mostly "quicksand" type formations and thecritical velocities of sand in a wellbore is extremely low. Consequently, sandis very likely to enter the horizontal wellbore if not preventive measure istaken. Problems of sand production in a horizontal well is more complicatedthan in a vertical well due to difficulty in cleaning sands in horizontalwellbores. The present study discusses the problems of sand production in ahorizontal well and offers production in a horizontal well and offersrecommendation in controlling them. Physical simulation of the top part of thehorizontal well showed that both gravitational and inertial forces helpminimizing sand production. This will mean that increasing flow rates willdecrease sand production. Experimental evidence showed that production. Experimental evidence showed that selection of liner diameter and wire spacingare important parameters in controlling sand productions. Permeability damagedue to particle productions. Permeability damage due to particle mixing in theannulus was quantified. It was shown that smaller annulus is of more importancein the case of smaller wire spacing, lower oil viscosity and thinner payzone. Introduction Sand production is considered to be one of the major problems that haveperplexed the petroleum industry. Every year the petroleum industry spendsmillions of dollars in sand cleaning, repair problems related to sandproduction and lost problems related to sand production and lost revenues dueto restricted production rates. Consequently, sand control has been a researchtopic for over five decades. Uncontrolled sand production is very expensive dueto additional production is very expensive due to additional operating expenses(such as pump change, well cleanup, etc.), lost revenues, and creation ofpotentially hazardous situation. These problems are potentially hazardoussituation. These problems are magnified for horizontal or slanted wells forwhich well cleaning technique is not trivial. Additional expenses associatedwith sand production include clean out and disposal of sand and workover coststo return the well to production. The lost revenue due to restricted orcompletely shut in production is often a hidden expense and not alwaysproduction is often a hidden expense and not always considered in economiccalculations. Most of the early research work conducted by petroleum industry involved indesigning largest petroleum industry involved in designing largest practicalsizes of gravels and liners with the practical sizes of gravels and liners withthe notion that this will also lead to highest production rates. For manyyears, the philosophy of production rates. For many years, the philosophy of" if all sand production is stopped, the fluid production will bestopped" seemed to dominate the production will be stopped" seemed todominate the petroleum industry. Recent research efforts, petroleum industry. Recent research efforts, however, have focused on completion and control whilemaintaining highest well productivity. Sand control Methods Sand control methods may be classified as mechanical, chemical andmechanical/chemical. Mechanical methods of sand control prevent sand productionby stopping the formation with liners, production by stopping the formationwith liners, screens or gravel packs. Larger formation sand grains are stopped, and they in turn stop smaller formation sand grains. Chemical control methodsinvolve in injecting consolidating materials into the formation to cement thesand grains. A combination of plastic consolidated gravel and screen may beused to controls and in some wells to provide increased stability to the pack.provide increased stability to the pack. Reasons For Sand Production Sand production occurs when the stresses on the formation exceeds thestrength of the formation.