Acid Systems and ICD Design Considerations For Stimulation

Abstract

The recent industry development of drilling ERD wells with horizontal laterals in the reservoir of 10,000 ft. or more has led to a greater use of passive flow control devices and swell packers to achieve the desired inflow or outflow profiles. Another desire is to perform stimulation treatments of the lateral especially in tight carbonate formations. However, such treatments can create high velocities through the Inflow Control Devices (ICDs) that inevitably leads to high turbulence and wall shear stress in the ICD which can cause severe erosion and corrosion of commonly used materials. There appears to be little experience and associated knowledge on corrosion mitigation to ensure ICD integrity after well stimulation. This paper will attempt to address such concerns through: Discussing and analysing ICD design considerations to avoid high corrosion areas and selection of high alloy materials to resist corrosion. Selection of appropriate acid system and method to prevent corrosion. Laboratory testing of acid formulations under high wall shear conditions as predicted from Computational Fluid Dynamics (CFD) of the ICD design at reservoir conditions. Laboratory measurements of the performance of corrosion protection additives in acid formulations under wall shear conditions. Other possible mitigation efforts to reduce the need for stimulation treatments. Each of these factors presents limitations which either restricts the use of aggressive acid systems or requires alternative acid systems that can lead to increased treatment cost and/or sub-optimal stimulation of the reservoir through the ICDs. This paper discusses one producing company's effort to systematically improve the overall performance of stimulation through ICDs while maintaining the integrity of the lower completion liner.

Degradation profiles of poly(methylene oxide) and poly(glycolic acid) for inflow control devices in oil wells

“…To promote divergence, some mechanical devices can be associated to perform complementary functions. One example of this equipment is inflow control devices (ICDs), which can be represented by tubes with a designed perforation gradient (diverting liner and Controlled Acid Jet (CAJ) liner) and tubular accessories for flow restriction provided by specialized companies . They provide friction loss by channeling fluids (such as in acid treatments) through a designed set of holes.…”

“…The imposed friction loss alters the natural formation flow profile during oil production [Figure (a)] or during the injection of any kind of fluid in long formation intervals. For the purpose of this study and to simplify the discussion, all of the equipment used are considered ICDs because they all had similar work principles …”

“…Normally, IDC cannot be designed to simultaneously control production flow and treatment divergence because these two conditions need different friction loss profiles . In high‐rate oil wells, the application of ICDs designed for divergence can introduce undesirable friction loss to the oil flow [Figure (b)] and can, therefore, cause production impairment.…”