TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractEffective matrix acidizing of horizontal and multi-lateral wells is a very difficult task. Unlike vertical wells, horizontal wells can extend several thousands feet in the formation.

Effective matrix acidizing of horizontal and multilateral wells can be a highly challenging task. Unlike vertical wells, horizontal wells can extend several thousand feet into the formation. Reservoir heterogeneity and the length of the horizontal leg can make acid placement and diversion very difficult. In addition, the low drawdown encountered in horizontal wells results in longer times to lift the spent acid from the well, especially in tight formations.To achieve better acid diversion in horizontal wells drilled in carbonate reservoirs, a viscoelastic-surfactant-based system was used. The components of this new system are HCl and a viscoelastic surfactant. The acid dissolves calcite and dolomite minerals and produces calcium and magnesium chlorides. The increase in pH forces the surfactant molecules to form rod-shaped micelles. The produced chloride salts further stabilize these structures, especially at high temperatures. The rod-shaped micelles will significantly increase the viscosity of the acid, diverting the acid into tight, unstimulated, or severely damaged zones.More than 100 wells with openhole (OH) completions were successfully stimulated in two offshore oil fields in Saudi Arabia by use of the new acid system. With a water zone 30 ft away from these OH sections in one of the fields, growth of any dominant wormhole into these sections could increase water production. The wells that used the new treating fluid produced an average of 1,600 BOPD more than conventionally treated wells, with no indication of water production. Field results [pre-and post-oil and -water production rates and flowing wellhead pressure (FWHP)] demonstrate the effectiveness of the new acid system to matrix acidize long horizontal wells with OH completions. The simplicity of the system makes it the fluid of choice, especially in offshore and sour environments. The absence of metallic crosslinkers in this system eliminates problems associated with sulfide precipitation in sour wells.

No abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractEffective matrix acidizing of horizontal and multi-lateral wells is a very difficult task. Unlike vertical wells, horizontal wells can extend several thousands feet in the formation.

TX 75083-3836, U.S.A., fax +1-972-952-9435. AbstractPassive ICDs (Inflow Control Devices) are being used to enhance performance of horizontal wells in unfavorable environments such as non-uniform permeability and/or pressure variations along horizontal sections. This is the first ever attempt, to the best of our knowledge, at using ICDs to manage inflow from two laterals connected to a motherbore. Furthermore, this well is a 3 7/8" openhole multi-lateral with a 2 7/8" ICD completion.This paper presents how passive ICD completion technology is used to optimize well productivity in a multi-lateral well. This carbonate well was sidetracked to increase reservoir contact and create the required multi-lateral. Subsequently, the ICDs were run, and to confirm the inflow profile along the length of the of the ICD completion, a PLT survey was conducted. The actual rate and inflow profile compared favorably with the predictions as per design of the ICD completion. This paper will show the well design, the actual PLT vs modeled results, and discuses future utilizations for this technology.The key factor in the success of this project was the use of the 2-7/8" ultra-slim ICD completion, which was optimized based on numerous wellbore hydraulic simulations, to determine the appropriate number of ICD units and compartments to balance the required off-take from each lateral, and from individual compartments in the motherbore section.