Journal of Petroleum Technology October 2012 : Page 60
Fracmaster’s Quad Pack can be tied in to its ventless system as a backup to smaller systems, resulting in emissions-free completions. Reduced-Emission Completions Improve Safety, Decrease Footprint Tayvis Dunnahoe, JPT Staff Writer I n its proposed New Source Perfor-mance Standards (NSPS) established in August 2011, the EPA estimated that, of the 25,000 new and modified fractured gas wells completed each year, approximately 3,000 to 4,000 cur-rently employ reduced-emission com-pletion (REC). Once finalized, the new rule will increase this number to more than 21,000 RECs annually as opera-tors comply with the proposed NSPS. By 2015, every hydraulically fractured well will be required to use a green comple-tion to capture and measure all oil and gas released during the flowback and drillout phases. Typically, the gas/liquid separa-tor installed for normal well flow is not designed for the high-rate, four-phase (gas, hydrocarbon liquid, water, and sand) flow of a typical shale well. A com-mon practice for the initial well com-pletion has been to produce the well to a pit or tanks where water, hydrocar-bon liquids, and sand are captured and slugs of gas vented to the atmosphere or flared. Completions can take any-where from one day to several weeks, during which time a substantial amount of gas may be released to the atmosphere or flared. Green completion equipment is only necessary for the time it takes to complete the well. Operators typically transport this system from site to site to be used in a number of well completions, often on a 60 JPT • OCTOBER 2012
Reduced-Emission Completions Improve Safety, Decrease Footprint
Tayvis Dunnahoe, JPT Staff Writer
In its proposed New Source Performance Standards (NSPS) established in August 2011, the EPA estimated that, of the 25,000 new and modified fractured gas wells completed each year, approximately 3,000 to 4,000 currently employ reduced- emission completion (REC). Once finalized, the new rule will increase this number to more than 21,000 RECs annually as operators comply with the proposed NSPS. By 2015, every hydraulically fractured well will be required to use a green completion to capture and measure all oil and gas released during the flowback and drillout phases.<br /> <br /> Typically, the gas/liquid separator installed for normal well flow is not designed for the high-rate, four-phase (gas, hydrocarbon liquid, water, and sand) flow of a typical shale well. A common practice for the initial well completion has been to produce the well to a pit or tanks where water, hydrocarbon liquids, and sand are captured and slugs of gas vented to the atmosphere or flared. Completions can take anywhere from one day to several weeks, during which time a substantial amount of gas may be released to the atmosphere or flared.<br /> <br /> Green completion equipment is only necessary for the time it takes to complete the well. Operators typically transport this system from site to site to be used in a number of well completions, often on a truck-mounted skid. Don Atencio, manager at Fracmaster, said, “The setup for a green completion depends on the area and the type of well you are completing.” There is no set amount of equipment that is required.<br /> <br /> An REC can be performed with one self-contained unit, or it can be set up using individual components. Each job is based on need, the volume of gas and fluids being produced, and the size of the pad. For a multiwell pad, the equipment set up can be extensive. “Some of the work we are doing in New Mexico involves three major pieces of equipment that are too big to load onto one skid,” Atencio said.<br /> <br /> Essential equipment for RECs includes the plug catcher with multiple flow paths, which gathers the “trash” coming out of the wellbore as the frac plugs are drilled out just after fracturing. Additional equipment includes a sand buster that effectively removes sand from the flowback stream, a choke manifold which controls the pressure from the wellbore, a three-phase separator, a ventless fourphase tank with on-the-fly clean-andpurge technology, a mistless gas buster flowback tank, and a flare stack.<br /> <br /> Traditionally, flowback is then routed to an open-top tank where the methane is vented. This is the catalyst for the EPA’s new ruling. Providing a closed-loop system capable of capturing this methane stands to reduce methane emissions greatly and essentially make shale gas development greener in the process. Fracmaster deals in four- and five-stage vessels designed to separate water, oil, gas, and sand/trash. “With the minimum requirement to flare, our current system Is also set up to meter the gas and then burn it off or deliver to a sales line when feasible,” said Atencio.<br /> <br /> One of the challenges for many operators is brought on by a lack of substantial gas or pressure to operate the separation equipment. “The system has enough retention time and volume to further separate any gas molecules that may be entrained in the water,” he added.<br /> <br /> Known as a ventless system, Fracmaster’s REC technology uses pressurized vessels to send flowback water through a tortuous path to catch any particulates and to break out any gas to be sent to a flare stack. “The fluid being released is completely free of gas,” Atencio said.<br /> <br /> The company currently operates 15 units, and, while a ventless system comes at a premium, it serves to assist operations.<br /> <br /> REC equipment relies on pressure or gas to drive the system. “As you’re bringing wells on, you must have enough pressure downstream of your separation equipment to provide access into the gathering line,” said Adam Berig, air quality lead for the southern Rockies at Encana. Pressures typically build over the course of the completion. Early phases of that flowback process may not have enough pressure to buck gathering system requirements.<br /> <br /> Initial flowbacks often do not provide enough gas to operate the separation equipment. For this reason, many operators rely on an open-top tank system, which cannot function as a closed loop allowing valves to open and close when needed. New systems are working to develop electric sensor technology that would remove the requirement for gas or air supply to operate, but these are still in their infancy. According to Fracmaster, its ventless tank systems or vessels can operate with no gas and very little pressure. “As you’re flowing fluid into the system the air begins to compress, thereby generating its own pressure,” Atencio said. The pressure can be preset to release at a certain level when needed, so the ventless systems can maintain a preset internal pressure to dump water or oil and operate the equipment when no gas is present allowing it to function at a level that is 100% green. Any gas slugs that occur are automatically diverted and sent to the flare stack. “The unit literally controls the level of the fluid and pressure in the vessel,” Atencio said. The system captures any amount of gas and sends it to a flare, or enough pressure and volume can send the gas downline to market.<br /> <br /> Operations Under the New Rule <br /> <br /> “‘Green completions’ is not clearly defined; however, the goal is to provide a completely closed system capable of measuring all oil and gas without freeing hydrocarbons into the atmosphere,” said Michael Tangedahl, vice president of environmental solutions production at Schlumberger. REC technology is not new and has been in use since the early 2000s. States such as Colorado and Wyoming have already mandated green completions to improve air quality in heavy development areas.<br /> <br /> The Colorado Oil and Gas Conservation Commission (COGCC) passed regulations for green completions in 2008. “Encana was using REC technology prior to this legislation,” Berig said. The company provided input to the COGCC on its process when the rules were being drafted.<br /> <br /> Part of the challenge for REC use lies in the type of well that is drilled. Delineation wells are typically near other developed areas and can easily be green completed, with the captured gas being delivered to a pipeline and sold, which is the ultimate goal of the technology. For exploration wells, this can be a bit more daunting when infrastructure is not readily accessible. However, the new rules will require a minimum of flaring for any captured gas. As the technology improves, this will become more attainable. <br /> <br /> The company also conducts green completions in Wyoming, which passed its ruling at the same time as Colorado. The use of REC is established in these areas, but in many other plays the technology will some time to be adopted. Encana currently green completes about 90% of its shale wells. In the mid-continent region, namely Texas and Louisiana, REC can be a bit more challenging. “The challenge there lies in pushing exploration in advance of gas gathering systems,” Bryan Clode, divisional group lead at Encana. The region is known for fairly high producing wells that come on very strong. “Having adequate separation capacity there physically strong enough to deal with the pressures during that flowback is a challenge that is sometime faced,” he added.<br /> <br /> “From an operations standpoint, the new regulations will not incur a huge change in the way we are doing things,” Berig added. The primary challenge for operators currently employing REC technology will be in the record keeping. The new rules require a stringent policy of record keeping including the use of a GPS camera with timestamped photos of REC equipment and a two-day notice on each new completion. “Record keeping will be the biggest development,” said Clode.<br /> <br /> Equipment Constraints <br /> <br /> One of the issues concerning the new rule on green completions is the availability of equipment. Currently, operators deploy this technology on an at-will basis with the exception of states that have already passed legislation requiring the process.<br /> <br /> A number of companies conduct RECs, including Weatherford, whose Secure Drilling Group recently received an award from the US Bureau of Land Management for its closed-loop system in New Mexico. Schlumberger’s M-I Swaco is also active in providing REC equipment to the new market, along with a number of other companies. The EPA’s new rule extends the requirement to 2015, giving operators ample time to develop relationships with service providers.<br /> <br /> It is expected that the new rule will be carried out as a work practice, meaning that companies will be ex pected to capture as much gas as possible. Gas that cannot be sold will be flared, and venting will become a thing of the past.<br /> <br /> “We feel like we are in line with the new regulation. It won’t be a big change for us,” Berig said.<br /> <br /> GREEN COMPLETIONS<br /> <br /> Conventional chokes have no method to detect internal washing of parts within the choke body. Fracmaster’s Compact Blast Barrel Choke with Wear Monitoring Technology compares calculated flow rates against those measured to determine choke wear. In the event of washing, it can be reset to the original choke size, or it can shut itself down in the event of a catastrophic washout.<br /> <br /> Safety Through Engineering <br /> <br /> Many operators cite the added expense of reducedemission- completions (REC) technology as an issue with the new EPA rules. Innovation will serve to lower the initial cost. The need for a simple, high-tech solution that improves safety is being achieved through engineering. “For the first 24 to 48 hours of a flowback, which is the most crucial point, these systems function the same as standard separation equipment,” Fracmaster’s Don Atencio said.<br /> <br /> For this purpose, Fracmaster is commercializing its system with remote monitoring capability. Multiple systems can be viewed on a computer monitor and operated from a central command center. Pressure, differential pressure, flow rates, and fluid levels can each be tracked remotely. “A technician has the capability to log on to a computer and change the parameters and/or the choke size just by dialing in,” he said.<br /> <br /> The company’s Blast Barrell choke is perhaps the latest advance within the REC market. The choke is designed with monitoring capabilities that can actually determine the rate of internal wear. Sensor ports monitor choke differential pressure and the breach chamber alarming system sensor port monitors the internal breach chamber which, if compromised, will initiate ESD or automatically change the flow path and alarm the operator if an internal wash out occurs. Choke wear is determined by comparing a measured flow rate to a calculated flow rate. As an example, if a well is operating on 24/64 choke, the redesigned choke can alert and correct for any choke erosion. Should the system determine that the well is now flowing at 28/64 choke rate (signifying internal wear), the system is capable of dialing itself down to achieve the original choke size. This function can be preset or done actively from a command center.<br /> <br /> More importantly, this feature enhances safety in the event of a catastrophic washout. If the seat is blown out by internal wear, the system is capable of shutting down automatically. It can also operate on a preset function where parameters of wear tolerance can be identified beforehand. The system can shut itself down and open up to a new choke, allowing the unit to be serviced and the parts changed.<br /> <br /> “It’s a safety system that allows you to operate away from the pressure,” Atencio said. In addition, the choke monitors the activity. In the event of a washout, an operator can determine when and how it occurred. The system charts the flow rate to identify the incidents leading up to the breech and how long it ran during the event.<br /> <br /> Remote monitoring reduces manpower, which is a benefit for both safety and cost concerns. More than 50% of the cost of a green completion is associated with labor. By limiting the onsite crew to one technician and monitoring the process remotely, operators may eventually cut their costs dramatically as the new EPA rule takes effect.<br /> <br /> Fracmaster’s blast barrel wear monitoring technology is field proven and is taking green completions to the next level. The critical part of the flowback phase occurs within the first 24 to 48 hours. Once this has past, flowback testing can eventually get to a point where the system functions as a standard separator and is monitored much like a pumper monitors a location. “The idea is that a field technician can service multiple wells or pads while the wells are watched and operated from a command center anywhere in the US,” Atencio said. “I don’t think that we can totally remove people from location because of all the other duties that are required on site such as managing water, but we feel we can greatly increase safety through engineering and reduce operating costs through technology,” he added.
Using a screen reader? Click Here