REMOVAL of WATER OR SAND in OIL/WATER and GAS/LIQUID/SOLID PIPELINES Pipeline Paul Jepson1, Cheolho Kang 2, Madan Gopal3 2003 Conference & Exposition

IBP332 03 INNOVATIVE IN-LINE SEPARATORS: REMOVAL OF WATER OR SAND IN OIL/WATER AND GAS/LIQUID/SOLID PIPELINES Pipeline Paul Jepson1, Cheolho Kang 2, Madan Gopal3 2003 Conference & Exposition

Copyright 2003, Brazilian Petroleum and Gas Institute - IBP This paper was prepared for presentation at the Rio Pipeline Conference <$ Exposition 2003, held in October, 22-24, Brazil, Rio de Janeiro. This paper was selected for presentation by the Event Technical Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the IBP. Organizers will neither translate nor correct texts received. The material, as presented, does not necessarily reflect any position of the Brazilian Petroleum and Gas Institute, its officers, or members. It's Author's knowledge and approval that this Technical Paper will be published in the Rio Pipeline Conference <$ Exposition 2003 “brouchure”

Abstract

In oil and gas production, multiphase mixtures are often separated before downstream processing. The separators are large, often 20 - 40 feet long and large diameter and use sophisticated internals. The costs are in the millions of dollars. Further, the sand and water in the flow can cause severe internal erosion and corrosion respectively before the flow reaches the separators.

The CC Technologies/MIST Inline Separation System is a cost-effective, efficient device for use in multiphase environments. The device is applicable for gas/solid, gas/liquid/solid and oil/water systems and offers exceptional separation between phases for a fraction of the cost of expensive gravity separators and hydrocyclones.

The System contains no moving parts and is designed to be of the same diameter as the pipe, and experiences low shear forces. It can be fabricated with standard pipes. The efficiency of the separator has been determined in an industrial scale, pilot plant test facility at CC Technologies in 4-inch diameter pipes and has been found to be in excess of 98-99% for the removal of sand. Two phase oil/water separation effectiveness is in excess of 90% in 1-stage and 95% in 2 - stage.

Introduction

Multiphase flow of gas and liquid in pipes is becoming a ubiquitous phenomenon in the oil and gas industry. Advancements in subsea completion and multiphase production technology have extended multiphase flow over relatively long distances to centralized gathering and separation systems (Shippen and Scott, 2002). These developments are becoming increasingly common, especially in remote and hostile locations such as the deepwater Gulf of Mexico. Also, as operating conditions become more severe, and the costs associated with well failure escalate, the need for effective sand control increases. In many cases, wells are not produced because of the potential damage from sand (Mathis, 2003). A multiphase separator that can be used for oil, water, gas or sand separation, particularly under downhole conditions would add significant value towards efficient and economic

1 V.P. - CC Technologies 2 Senior Engineer - CC Technologies 3 Senior Scientist - CC Technologies IBP332 030 management of oil and gas productions.

1 - Background

Separations technology plays a pivotal role in the supply of hydrocarbons from the production sites to the market. It is estimated that separations equipment constitutes close to 30% of the capital invested in oil and gas platforms, 60% of the capital invested in LNG fractionation and gas conditioning, and 50% of the capital invested in oil refineries. Furthermore, separations equipment consume a very significant portion of the energy used in the production, manufacture, and delivery of hydrocarbons to market (Bergermann et al., 2001). The prevalence of separations needs in the industry makes the applicable technologies very important in the profitability and operability of the production and manufacturing assets.

Traditionally, separations have been carried out using some type of momentum, gravity settling and coalescing. Separators may be vertical, monotube and dual-tube horizontal, or spherical (Shaban, 1995). Some systems may contain impurities or additives that can cause foam formation in gas-liquid systems and emulsions in liquid-liquid systems that will require “breaking” in order to prevent carry-over. Typically a de-foaming or de-emulsifying agent is added to accomplish this.

The major types of soild-gas separators are summarized by Hanly and Petchonka (1993). These include: inertial or impingement separators, Wet scrubbers, Fiber and fabric filters and electrostatic precipitators. Inertial and impingement separators have efficiencies less than 90%. The highest separation effectiveness (~99%) is obtained using Electrostatic precipitators, venturi scrubbers and fabric filters. In this paper, a novel inline separation system is described that can be utilized for separating two-phase gas/liquid, gas/solid and oil/water systems as well as three phase gas/liquid/solid mixtures. The oil/water and three phase separation require two stages.

2 - Experimental Setup

The experimental layout of the flow loop is shown in Figure 1. The specified amount of liquid is placed in a 1.14 m3 stainless steel storage tank (A). The liquid from the storage tank is then pumped into a 5.08-cm ID PVC pipeline by a low shear, progressive cavity pump (B). An additional water storage tank (E) of same capacity is used if two liquids are used at one time. A submersible pump (F) is used to pump liquid from this tank. The liquid flow rate of both the pumps is controlled by a variable speed controller.

Carbon dioxide gas is introduced into the system at an inlet pressure of 2.1 MPa from the 14 ton capacity storage tank (C). The flow rate of the carbon dioxide gas is measured using a variable area Omega gas flow meter (D).

The liquid flows into a 20-m long Plexiglas pipeline (10.16-cm ID). The flow direction then changes by 180 degrees and is sent through a 18 m long Plexiglas pipeline and then returned to the storage tank. A mounting with an injection valve (G) has been made on the top of the PVC pipe just before the 18 m long Plexiglass section for the insertion of solid as shown in the figure. 2 IBP332 030

The inline separation system of the length of 3.1 m is installed within the 18 m long Plexiglass pipeline. The schematic layout of the separation system is shown in Figure 2. A specially designed flow inducer conditions the flow which then passes into the separator. After the flow inducer, the pipe expands slightly where the densest flow decelerates whilst the gas (or oil in oil/water flow) passes through the inner pipe that is inserted into the expanded pipe. The sand and/ or liquid is collected and is allowed to drain into a collection tank (H). This tank can be easily emptied using a level control system (LC).

A. Liquid Storage Tank B. Low Shear Pump Outlet C. COz Tank D. Gas Flow Meter E. Water Storage Tank F. Submersible Pump G. Sand Injection Valve H. Collection tank

G®

Figure 1. Experimental Layout of the Multiphase Flow Loop

3 - Experimental Test Matrix

The operating pressure was 0.13 MPa and the system temperature was maintained at 25 C.The separation system was tested under the following operating conditions.

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Flow Separator inducer Valve8

Liquid / sand collection tank

Figure 2. Layout of the Separation System

Table 1. Test Matrix for the Separation Test

System Operating Range

Gas / Solid Gas: 6-30 ft/s (2 to 10 m/s) Solids: up to 350 microns Oil / Water Oil: 1-10 ft/s (0.3 - 3 m/s) Water: 1-10 ft/s (0.3 - 3 m/s) Water cut: 10 - 99% Oil viscosity: 1 - 100 cp

Liquid/Solid Liquid: 1—10 ft/s (0.3-3 m/s) Solids: up to 350 microns Gas / Liquid / Solid Gas : 6 - 30 ft/s (2 to 10 m/s) Liquid: 1—10 ft/s (0.3-3 m/s) Solids: up to 350 microns

4 - Results and Discussions

The following part explains the results obtained by conducting the experiments for solid/gas, liquid/solid, solid/liquid/gas, and oil/water, respectively. Also, the means to measure the different phases before and after separation has been expalined in the respective sections. No emulsion or foam formation took place while conducting these experiments. Based on the experimental procedure described above and the data gathered, the separation effectiveness was calculated for each of the system as shown in the Table 2. The effectiveness

4 IBP332 030 of each operation was calculated based upon the measurement done of the separated quantities of solid and liquids.

A. Solid - Gas A certain amount of sand (solid) is taken and measured using a measuring flask. This measured quantity of solid is then inserted into the system through the arrangement specially made on the top of the pipe. The gas/solid mixture then flows through the system into the flow inducer. Solid having higher density than the gas moves along the periphery of the pipe while the gas forms the central core flowing out of the inducer. The gas passes through the smaller diameter pipe inserted inside the separator and the solid is collected through an outlet of the larger section of the separator in the collection tank. The collected amount of sand is again measured using the measuring flask. The amount of sand collected after the separation was higher than 99 % of the total volume inserted into the system before separation.

B. Oil - Water The specified amount of water and oil from tanks A and E are pumped into the system using the respective pumps. The liquid flow rates are controlled by the variable speed controller. Similar to previous descriptions, the oil/water mixture flows into the system and then into the flow inducer conditioning the flow which passes into the separator. Oil flowing through the central core passes through the smaller pipe inserted into the separator and is returned to the collection tank. Water which flows the annular region is collected through an outlet of the larger section of the separator into the collection tank The amount of water collected from the oil/water mixture after separation was higher than 90 % of the total volume pumped into the system after the first stage. It was noticed that, if two separators are used then additional 5 % of water is removed from the oil - water mixture. Thus, an overall 95 % of water is separated. This shows that the performance of the separator increases with the increase in the number of stages.

C. Liquid - Solid The multiphase mixture of sand and water flows through the system into the flow inducer. It was observed that after the flow separates in two parts flowing into the separator. Here, sand is collected through an outlet of the separator while the liquid flows through the central pipe into the storage tank. The separated amount of sand is let to dry and then measured in the measuring flask. It was observed that amount of sand colelcted was higher than 98 % of the total input volume of the sand before separation.

D. Solid - liquid - Gas A measured amount of sand is poured into the system through the arrangement specially made on the top of the pipe. The multiphase mixture of sand, water and gas then flows through the system into the flow inducer. The multiphase mixture then separates out flowing into the separator. Solid and liquid form the annulus around the central core of gas which is lighter in nature than soild and liquid. The gas then passes through the small diameter pipe inserted inside the separator and is vented to the atmosphere through the storage tank. The sand/liquid mixture then flows through an outlet of the larger section of the separator in the collection tank. The mixture is then allowed to settle in the collection tank. Later the liquid is separated 5 IBP332 030 out and measured while the sand is left to dry and is again measured using the measuring flask. The separated mixture of sand and water, each constitute 98 % of the total volume that was into the system prior to separation.

Repetitive tests were carried out to check the performance of the separator for all above conditions. Same performance was achieved at all times.

Table 2. Effectiveness of In-Line Separation System

Sr. No. System Effectiveness A Solid- Gas >99% B Oil - Water > 90% in 1 stage > 95% in 2 stages C Liquid - Solid >98% D Solid - Liquid - Gas >98%

6 - Conclusions

A novel inline multiphase separation system has been developed. The system has numerous advantages. These include the fact that the flow inducer is the same diameter of the pipe. The system contains no moving parts and is also made from standard piping. The length is compact, varying from 6 - 10 ft (2 - 3 m). The footprint and costs are very small compared to gravity separator. The effectiveness of the separation system is very high and comparable to the highest quality separators used in industry today. It can effectively remove sand and water and reduces or eliminates erosion/corrosion problems. The separator requires emulsions to be de-emulsified with a residence time of less than 3 minutes to be effective.

7 - References

A. Bergermann, S. D , Polderman, H. G., and Bravo, J. L., “Shell Separation Technology From the Wellhead to the User” SPE Latin American and Caribbean Petroleum Engineering Conference, Buenos Aires, Argentina, March 2001. B. Mathis, S. P , “Sand Management: A Review of Approaches and Concerns”, SPE European Formation Damage Conference, The Hague, The Netherlands, May 2003. Hanly, J., Petchonka, J., J., “Equipment selection for solid gas separation”, Chemical Engineering (New York), v 100, n 7. Jul 1993, p 83-85. C. Shaban, Habib I. “Study of foaming and carry-over problems in oil and gas separators”, Gas Separation & Purification, v 9, n 2. Jun 1995, p 81-86. D. Shippen, M., E., and Scott, S. L., “A Neural Network Model for Prediction of Liquid Holdup in Two-Phase Horizontal Flow”, SPE Annual Technical Conference and Exhibition, San Antonio, Texas, October 2002.

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