Drill-stem testing (DST) is a proven method for reservoir characterization, which is important when designing well completion, future development strategies, and stimulation needs. If the completion designer has the ability to acquire accurate knowledge of fluid behavior as the hydrocarbon is produced to surface, decisions concerningcompletion strategies and expectations during well life can be greatly facilitated. The capability to collect a single-phase sample also is critical to reservoir modeling, as is achieving correct analysis of collected reservoir fluidswith accurate data collection frombottomhole gauges. Samples must remain as single-phase fluid samples during recovery, and introducing high-pressure nitrogen behind the sample helps maintain sample pressure. By monitoring nitrogen-charge pressure in the sampler carrier, the exact time the samplers are fired is known. Thus, monitoring gauges will show any abnormality such as whether the annulus was pressurized or if the samplers were fired at an unwanted moment. By integrating the sampler carrier gauge with a wireless acoustic data-acquisition system, status and confirmation of success of the trigger device are provided. Also, casing-pressure limitations are reduced by actuating downhole tools using acoustic telemetry instead of annulus pressure. This paper discusses offshore field operations in Brazil to illustrate the importance of correlating gauge data from sample well fluids with a wireless acoustic telemetry system, and also, how the successful application of a wirelessly controlled DST work string composed of a data-acquisition system, an acoustically controlled tester valve, and samplers can significantly improve well-testing strategies.

Historically, a fracture treatment with proppant is performed with a dedicated workstring connected to downhole completion equipment (such as a permanent packer, a tubing seal receptacle (TSR), or a locator assembly). This paper discusses offshore field operations in Brazil to illustrate how surface and downhole equipment, including a temporary completion string, were capable of meeting these challenges for hydraulic fracturing using ceramic proppants, followed by an acid job before a drillstem test (DST), which saved at least 6 days of rig time.When performing a DST with a temporary completion string, there are risks associated with using this type of fracturing treatment these mechanical tools can lock up if they are operated with proppant still packed in the operating sections (such as the tester valve and circulation valve). It is recommended that during the job the tool operation should be minimized to the absolute minimum because proppant can be packed in other areas of the tools. Halliburton performed extensive testing before the operation to determine the erosional limits of the DST tools; as a result of this testing, the maximum flow rate of the fracturing process was limited to 23 bbl/min. In this treatment, debris-tolerant valves, rather than standard valves were used. The debris-tolerant valves were specifically designed and tested to manage more debris.The well-test surface equipment was made of a solid-tolerant design, including a choke manifold (high abrasion tolerance), a four-phase separator, which was used to separate the solids, and surge tanks that are suitable for managing well flow that contains solids. Additional atmospheric tanks were provided in the test plant as part of a contingency plan to store fluids in the event of a high concentration of solids or/and untreatable fluid, which cannot be discarded or burned; sensors for solids were installed downstream from the choke manifold.During the hydraulic fracturing operation, 2,760 bbl of fracturing fluid containing the 20/40 mesh size proppant was pumped at a rate of 23 bbl/min with a maximum concentration of 6 lbm/gal. During the fracturing job, a screenout occurred, and the contingency plan was followed, removing most of the proppant inside the string. The well-testing plant received 130 bbl of the fracturing fluid at the surface during the cleanup of the well. The DST tools were fully functionable after the fracture treatment, and the test was successfully performed.The main objectives of well testing included the characterization of the reservoir (primarily, all variables to calculate the productivity index and the reservoir fluid (specific gravity (SG) of oil and gas/oil ratio (GOR). A stimulation technique is commonly used to increase the PI, and in some cases, with exploratory wells, the stimulation and well testing are combined to gather information to determine the effectiveness of the technique and whether or not this method is sufficient to make the block lucrative. One of these stimulation techniques is hydraulic fracturing, whi...

An LNG plant in Australia was designed to maximize energy efficiency and minimize greenhouse gas emissions. In steady-state operations, its greenhouse gas emissions are lower than any in-country LNG project. Typically, gas supplied from two offshore fields contains CO2 (~14%) and high-volume operations run smoothly. At the time of this project, an injector well was found to have critically high CO2 levels (99%), and two other injector wells were shut-in due to pressure anomalies. A solution was needed to confirm casing isolation and detect leakage, while maintaining well barrier integrity and monitoring pressure/temperature below the tubing hanger plug. An innovative acoustic transmission platform served as a barrier assurance tool. A transmitter module (below the plug) has pressure/temperature sensors sending data through tubular/casing walls. A receiver module (above the plug) also houses pressure/temperature sensors. Once configured and deployed downhole, barrier installation is recorded, and barrier setting is verified before pressure testing. During the pressure test, sensors record pressure/temperature (in Wireline mode or fed live to surface) from either side of the barrier, confirming its integrity. The integrated wireless barrier monitoring solution exceeded customer expectations, with continuous acoustic and wireless communication maintained throughout the entire operation. Simultaneous monitoring of two wells for 500+ hours accurately documented the barrier integrity via pressure testing results. The system was run downhole in conjunction with a non-explosive slickline setting tool and retrievable bridge plug allowing to not only log the setting sequence for quality assurance but also record the pressure & temperature across the barrier. Conducted on-location, the customer was able to witness the plugs being successfully set. They then received positive confirmation of established well barrier, by continuous monitoring of the pressure between the two barriers and interpreting data from the wireless system in real time. This combined technology approach reduces time to troubleshoot and verify barriers, enabling quick evaluation of the leak source. Other benefits include significant time savings over traditional isolation methods, improving personnel safety in the well bay area by conducting real-time diagnostics, while also optimizing the suspension to allow efficient intervention or abandonment operations. The main objective of the operation was met, and verification of the shallow set plug was achieved. Barrier verification without the acoustic real-time wireless system would have been questionable. During well intervention for a major LNG plant operator in Western Australia, the novel wireless barrier monitoring solution delivered efficient, real-time pressure testing and verification to ensure success. This marks the first global installation of an integrated barrier system, combining retrievable bridge plug with wireless acoustic telemetry in supercritical CO2 disposal well. It not only allows a shallow bridge plug to be verified as a leak-free barrier, but it also enables efficient evaluation of the entire well barrier envelope.

Well testing is a proven method for reservoir characterization, which is important for well-completion design, future development strategies, stimulation needs, and determining the commercial feasibility of the reservoir. This paper presents a surface data-acquisition system and its applications for rigless well-testing operations. Drill-stem testing (DST), which is classified as a temporary completion of a well, typically involves a large and complex operation. A key activity during DSTs is collecting downhole pressure and temperature data using gauges at the bottom of the well that monitor pressure changes throughout the operation. Particularly crucial are the shut-in and initial build up, which provide insight into major reservoir properties. While shutting in the well at the bottom reduces the effects of wellbore storage, providing the most accurate downhole measurements, it also requires a rig and numerous personnel to prepare the well and run in hole (RIH) the test string. A rigless DST operation using a surface closure and surface data-acquisition system has been used in several wells to optimize data acquisition recovery as a non-invasive alternative to running downhole pressure gauges for pressure-transient well testing. The effectiveness of the data-acquisition system provides advantages and accountability by avoiding the cost and risk of running equipment downhole and monitoring tests in real-time at surface. The surface gauges acquire high-resolution pressure data at the wellhead during flowing and shut-in, which are then converted to bottomhole conditions using proprietary models. Because this technique is nonintrusive, it can be used to test wells in which downhole gauges are impractical or cost prohibitive, such as highly deviated, horizontal wells with tubing restrictions, sour-gas, high-pressure wells with high bottomhole temperatures, and low-cost evaluations. For mediumto high-permeability formations, a three-day test is typically sufficient to calculate basic near-bore and reservoir properties, including skin, permeability, and initial pressure. Longer tests that track pressure changes to reservoir boundaries can also be used to calculate the reservoir size. The data-acquisition system has proven its efficacy after enabling a low-noise response and low-pressure changes resulting from temperature effects. Based on data provided by the data-acquisition system, the operator designed a well-testing campaign and achieved results typical of those expected using a conventional approach.