Extended-Time Conductivity Testing of Proppants Used for Multi-Stage Horizontal Completions

The American Petroleum Institute Recommended Practice 19-D (2018) is the current industry standard for conductivity testing of proppants used in hydraulic fracturing. Similar to previous standards from both the API and ISO, it continues the practice of measuring a "reference" long-term conductivity after 50-hours of time at a given stress. The fracture design engineer is then left to estimate a damage factor to apply over the life of the well completion based on correlations or experience. This study takes four standard proppants used for multi-stage horizontal well completions in North America and presents test data over 250-days of "extended-time" at 7,500 psi of effective stress. The API RP 19-D procedure was followed for all testing, but extended for 250-days duration for the four proppant types: 40/70 mesh mono-crystalline "White" sand, 40/70 mesh multi-crystalline "Brown" sand, 100 mesh "Brown" sand, and 40/70 mesh Light Weight Ceramic (LWC). The 7,500 psi stress condition was chosen to replicate initial stress conditions for a 10,000 feet deep well with a 0.75 psi/ft fracture gradient - typical of unconventional resource plays such as the Bakken formation of North Dakota or the Delaware Basin in west Texas. Results presented provide a measure of the amount of damage occurring in the proppant pack due to time at stress. To the authors’ knowledge, there has never been any extended-time conductivity data published for multiple proppant types over the timeframe completed in this study - despite the obvious need for this understanding to optimize the stimulation design over the full life of the well. Results for the four proppant types are presented as conductivity curves as a function of time for the 250-days of testing. Pack degradation is shown to follow a semi-log decline. Late time continued degradation for all materials is extrapolated over the life of a typical well (40 years), and compared to extended-time particle size distribution and crush data to explain the results observed. Extended-time data such as this 250-day study have never been published on proppants such as these despite the fact that fracture conductivity has a major impact on the productive life of a well and the ultimate recovery of hydrocarbons from the formation. The data presented should be of great interest to any engineer involved with completion designs, or reservoir engineers assessing the productive life and ultimate recovery in the formation since economic optimization is primarily driven by the interplay of fracture length/area with extended-time in-situ fracture conductivity.

Application of Integrated Far-Field Diversion Technology in Multistage Acid-Fracturing: Lesson Learnings from Unconventional Field North Kuwait

The unconventional Bahrah field is a high potential field which poses several challenges in terms of hydrocarbon flow assurance through highly heterogeneous tight carbonate intervals with poor reservoir quality and curtailed mobility. Due to this, the field development strategies have prioritized well completion using horizontal acid fracturing technology over vertical wells. During fracturing, the acid system tends to form highly conductive channels in the formation. Most of the fluid will flow into the path of least resistance leaving large portions of the formation untreated. As a result, the fracturing treatment options dwindle significantly, thus reservoir stimulation results are not optimum in each stage. Achieving complete wellbore coverage is a challenge for any acid frac treatment performed in long lateral with variations in reservoir characteristics. The multistage acid fracturing using Integrated Far-field Diversion (IFD) is performed using selective openhole completion, enabling mechanical annular segmentation of the wellbore using swellable packers and sliding sleeves. The mechanical as well as chemical diversion in IFD methodology is highly important to the overall stimulation success. The technique includes pumping multiple self-degrading particle sizes, considering the openhole annular space and wide presence of natural fractures, followed by in-situ HCL based crosslinked system employed for improving individual stage targets. A biomodal strategy is employed wherein larger particles are supplemented with smaller that can bridge pore throats of the larger particles and have the desired property of rigidity and develop a level of suppleness once exposed to reservoir conditions. The IFD diversion shifts the fracture to unstimulated areas to create complex fractures that increase reservoir contact volume and improving overall conductivity. This paper examines IFD in acid fracturing and describes the crucial diversion strategy. Unlike available diverters used in other fields, the particulates are unaffected at low pH values and in live acids. Proper agent selection and combination with in-situ crosslink acid effectively plug the fracture generated previously and generate pressure high enough to initiate another fracture for further ramification. The optimization and designing of the IFD diversion in each stage plays a key role and has helped to effectively plug fractures and realize segmentation. Concentration of diversion agents, volume of fluid system and open-hole stage length sensitivity plays vital role for the success of this treatment. The application of IFD methodology is tuned as fit-for-purpose to address the unique challenges of well operations, formation technical difficulties, high-stakes economics, and untapped high potential from this unconventional reservoir. A direct result of this acid fracturing treatment is that the post-operation data showed high contribution of all fractured zones along the section in sustained manner. Furthermore, this methodology can be considered as best practice for application in unconventional challenges in other fields.

Production Monitoring of Multilateral Wells by Quantum Marker Systems

Reliable information about the inflow composition and distribution in a multilateral well is of great importance and an existing challenge in the oil and gas industry. In this paper, we present an innovative method for dynamic monitoring of inflow profile based on quantum marker technology in a multi-lateral well located in West Siberia. Marker systems were placed in the well during the well reconstruction by horizontal side tracking with the parent borehole remaining in production. This way of reconstruction allows development of the reservoir drainage area with a lateral hole and bringing the oil reserves from the parent borehole into production, which results in an increased flow rate and improved oil recovery rate. Placement of marker systems into parent borehole and side-track for fluid distribution monitoring allows to evaluate the flow rate from every borehole and estimate the effectiveness of performed well reconstruction. Marker systems are placed into the parent borehole as a downhole sub installed into the well completion string. For the side-track polymer-coated marked proppant was injected during hydraulic fracturing to place markers. The developed method was reliably used for an accurate and fast determination of the inflow distribution in a multi-lateral well which allows more efficient field development and also enabled us to provide effective solutions for following challenges: Providing tools for timely water cut diagnostics in multilateral wells and information for water shut-off method selection; Selecting the optimal well operating mode for effective field development and premature flooding prevention in one or both boreholes; Evaluating whether well construction was performed efficiently, and an increased production rate was achieved; Leading to a considerable economic savings in capital expenditure.

A 3-D groundwater isoscape of the contiguous USA for forensic and water resource science

A wide range of hydrological, ecological, environmental, and forensic science applications rely on predictive “isoscape” maps to provide estimates of the hydrogen or oxygen isotopic compositions of environmental water sources. Many water isoscapes have been developed, but few studies have produced isoscapes specifically representing groundwaters. None of these have represented distinct subsurface layers and isotopic variations across them. Here we compiled >6 million well completion records and >27,000 groundwater isotope datapoints to develop a space- and depth-explicit water isoscape for the contiguous United States. This 3-dimensional model shows that vertical isotopic heterogeneity in the subsurface is substantial in some parts of the country and that groundwater isotope delta values often differ from those of coincident precipitation or surface water resources; many of these patterns can be explained by established hydrological and hydrogeological mechanisms. We validate the groundwater isoscape against an independent data set of tap water values and show that the model accurately predicts tap water values in communities known to use groundwater resources. This new approach represents a foundation for further developments and the resulting isoscape should provide improved predictions of water isotope values in systems where groundwater is a known or potential water source.

The concept of evaluating the effectiveness of technologies for the development of low-pressure gas

As the title implies, the article consider issues of low-pressure gas development of the Aptian-Cenomanian gas-bearing complex, which is located in Western Siberia. An algorithm for substantiating the well completion technology has been proposed as a result of the conducted scientific research. The algorithm takes into account the likelihood of occurrence and development of complications that affect the achievement of the expected flow rate. The likelihood of these complications is significantly low compared to other scenarios; however, the consequences of the accidents under consideration have the greatest negative impact on well completion in terms of achieving the potential productivity of the well. The author proposes to assess the effectiveness of the planned work on two indicators, which will allow us to determine the degree of risk of incompleteness of the event in the planned technological operation and to assess the quality of implementation of the planned technology.

An Alternative Tool for Production Logging in Horizontal Wells

From year to year, well drilling is becoming more technologically advanced and more complex, therefore we observe the active development of drilling technologies, well completion and production intensification. It forms the trend towards the complex well geometry and growth of the length of horizontal sections and therefore an increase of the hydraulic fracturing stages at each well. It's obvious, that oil producing companies frequently don't have proved analytical data on the actual distribution of formation fluid in the inflow profiles for some reasons. Conventional logging methods in horizontal sections require coiled tubing (CT) or downhole tractors, and the well preparation such as drilling the ball seat causing technical difficulties, risks of downhole equipment getting lost or stuck in the well. Sometimes the length of horizontal sections is too long to use conventional logging methods due to their limitations. In this regard, efficient solution of objectives related to the production and development of fields with horizontal wells is complicated due to the shortage of instruments allowing to justify the horizontal well optimal length and the number of MultiFrac stages, difficulties in evaluating the reservoir management system efficiency, etc. A new method of tracer based production profiling technologies are increasingly applied in the global oil industry. This approach benefits through excluding well intervention operations for production logging, allows continuous production profiling operations without the necessity of well shut-in, and without involving additional equipment and personal to be located at wellsite.

Adoption of Innovation and Technological Advancement Deployment

The main objective of the paper is to outline initiatives associated with leveraging creativity and innovation to sustain operational excellence. It will cover processes, applications and best practices toward continually leveraging creative and innovation such as the development of innovation team toward creating a collaborative environment in the generation, identification and development of ideas and new technological advancement deployment. The processes described will cover (1) the continuous monitoring and management update of innovation submissions, implementation and self-development course completion, (2) recognition for value addition resultant from technological deployment, (3) Technical Review Committee (TRC) centralization and streamlining of evaluating technologies and best practices, (4) the assignment of challenging targets and (5) the initiation of special innovation campaigns for pressing and challenging matters has resulted in various major accomplishments. The establishment of the 4th Industrial Revolution (IR 4.0) team to address production engineering and well services challenges and collaborate for articulate, smart, more efficient and effective resolutions, process improvements and decision making. The results were remarkable with an incremental increase into intent to submit a patent file consideration, patenting, technology deployment and production of technical manuscripts addressing the unique achievements as well as the submission of awards applications. Technical collaboration toward triggering resolutions to ongoing operational challenges has resulted in various internal in-house built strides of best practices and other collaborative initiatives with other services providers such as: Intelligent Field Equipment Industrial Professionals Training: Special training for intelligent field equipment associated with smart well completion (SWC) exercising and optimization, data retrieval from multiphase flow meters (MPFMs) as well as a permanent downhole monitoring system (PDHMS) and conducting basic preventative maintenance (PM) requirements. Multiphase Flow Metering (MPFM) Advanced Monitoring System: An in-house developed MPFM system advanced monitoring to enable production/Intelligent Field engineers to monitor and diagnose MPFMs healthiness in all fields. It includes a validation mechanism to monitor and verify the different MPFM diagnostic data, alarming mechanism, flow rates and data visualization tools to verify the health of the installed base of equipment toward higher testing efficiency, reduction of manpower exposure to the field, and cost avoidance through minimizing operational logistical arrangements and minimization of unnecessary field visits by service providers. The ultimate intent is to heavily depend upon all employees to successfully propose solutions, and subject matter experts to coach employees in the successful implementation of practical resolutions to improve operations, optimize cost, and enhance employees’ satisfaction and engagement.

A Successful Application of Continuous Pack-Off Technology to Water Shutoff Recompletion for High-WCT Gravel-Packed Horizontal Well

Objectives/Scope Controlling the excessive water production from the high water cut gravel packing horizontal well is a challenge. The approach which uses regular packers or packers with ICD screens to control the unwanted water does not function well. This is mainly because of the length limitation of packers which will make the axial flow resistance insufficient. Methods, Procedures, Process In this paper, a successful case that unwanted water is shutoff by using continuous pack-off particles with ICD screens (CPI) in the whole horizontal section in an offshore oilfield of Bohai bay is presented. The reservoir of this case is the bottom-water high viscosity reservoir. The process is to run 2 3/8" ICD screen string into the 4" screen string originally in place, then to pump the pack-off particles into the annulus between the two screens, and finally form the 360m tightly compacted continuous pack-off particle ring. Results, Observations, Conclusions The methodology behind the process is that the 2-3/8" ICD screens limit the flow rate into the pipes as well as the continuous pack-off particle ring together with the gravel ring outside the original 4" screens to prevent the water channeling into the oil zone along the horizontal section. This is the first time this process is applied in a high water cut gravel packed horizontal well. After the treatment, the water rate decreased from 6856BPD to 836.6BPD, the oil rate increased from 44BPD to 276.8BPD. In addition, the duration of this performance continued a half year until March 21, 2020. Novel/Additive Information The key of this technology is to control the unwanted water by using the continuous pack-off particles instead of the parkers, which will bring 5 advantages, a) higher efficiency in utilizing the production interval; b) no need to find the water source and then fix it; c) the better ability to limit the axial flow; d) effective to multi-WBT (water break though) points and potential WBT points; e) more flexible for further workover. The technology of this successful water preventing case can be reference to other similar high water cut gravel packed wells. Also, it has been proved that the well completion approach of using CPI can have good water shutoff and oil incremental result. Considering the experiences of historical applications, CPI which features good sand control, water shutoff and anti-clogging is a big progress compared to the current completion technologies.

Well Integrity Leak Diagnostic Using Fiber-Optic Distributed Temperature Sensing and Production Logging

Fiber optics has many applications in the oil and gas industry. In recent years, fiber optics has found usefulness in leak detection. The leaks can be efficiently identified using fiber-optic distributed temperature sensing measurement, thereby mitigating the health, safety, and environmental (HSE) risk associated with well integrity. Further, a production log can be used to gain more insight and finalize a way ahead to resolve well integrity issues. An innovative solution-driven approach was defined, with fiber-optic distributed measurement playing a key role. Multiple leaks were suspected in the well completion, and a fiber-optic cable was run to identify possible areas of the leak path. After the fiber-optic data acquisition, a production log was recorded across selective depths to provide an insight on leak paths. After identifying leak depths, a definitive decision between tubular patching and production system overhaul was decided based on combined outputs of the fiber-optic acquisition and production log. Results are presented for a well where multiple leaks were successfully identified using the novel operational approach. Further, operational time was reduced from 3 days (conventional slickline memory or e-line logging performed during daylight operation) to 1 day (a combination of fiber-optic distributed temperature sensing and production log in a single run). The diagnosis of production system issues was completed in one shut-in and one flowing condition, thereby reducing the risk of HSE exposure with multiple flowing conditions (to simulate the leak while the conventional production logging tool is moved to different depths in the well). Additional insight on leak quantification was confirmed from the production log data, where one leak was noted at the tubing collar while the other leak was noted a few meters above the tubing collar. This observation was substantial in deciding whether to proceed with tubing patch or replace the entire production tubing. The novel operational approach affirms fiber-optic distributed temperature measurement's versatility in solving critical issues of operation time and reducing HSE exposure while delivering decisive information on production system issues. The paper serves as a staging area for other applications of similar nature to unlock even wider horizons for distributed temperature sensing measurement.