Wisconsin Public Service

With continually decreasing costs for underground distribution construction coupled with increasing outage and restoration times as a result of strong weather events, installing underground primary distribution is becoming a more frequently utilized method to decrease outages and improve system reliability. An analysis of detailed outage data indicates overhead circuit reliability cannot always be improved significantly through simple system hardening. Increasing storm damage, along with higher demands for reliability from customers, public utility commissions, and other regulatory agencies have led to the need to improve distribution system reliability performance. Wisconsin Public Service Corporation is currently in the process of converting a significant portion of its overhead electric distribution system to underground for reliability improvement purposes. The impacted areas of the distribution system are primarily concentrated in the heavily forested northern areas of Wisconsin Public Service Corporation's service territory. Beginning in 2014 and spanning a 5 year period, Wisconsin Public Service Corporation began replacing 1000+ miles of overhead distribution with underground facilities at a pace of approximately 200 miles per year. How does one design such a sophisticated and specialized system improvement program that incorporates environmental concerns, efficient circuit design, large scale customer engagement, and a focus on the circuits with the largest reliability issues? How could one prioritize the various segments of lines on the electric distribution system to achieve optimal results?

Technology Update The information in the article is based on paper SPE 176984, which was presented at the 2015 SPE Asia Pacific Unconventional Resources Conference and Exhibition in Brisbane, Australia, 9–11 November. An operator in the United States midcontinent region systematically analyzed different completion technologies and identified openhole multistage (OHMS) systems as a more cost-effective method than the cemented casing plug-and-perf (CCPP) techniques, used on previous wells, for increasing production and reducing development costs. The operator holds one of the largest acreage positions in the region and in 2014 had operated or participated in approximately 170 horizontal wells. The operator’s development focused mainly on the Mississippian Lime play in northern Oklahoma and the Marmaton play in the Oklahoma and Texas Panhandles. Each carbonate resource play required a thorough evaluation to assess the unique geologic characteristics and thoughtful application of technology to unlock significant amounts of previously untapped oil and gas deposits. These plays are composed of a mix of unconventional shale, carbonate, and sandstone plays. When developing its assets, the operator focused on creating a productive well, then on improving production and well cost. The steps taken by the operator included the following: comparing different completion methods analyzing completion costs implementing new technology to improve completions studying microseismic data to confirm assumptions and fine-tune completion design conducting tracer analysis to ensure all stages were contributing to production Lessons learned from each well were applied to future wells, and the operator realized further cost savings as it continued development of the region using OHMS completion systems. These cost reductions were achieved while preserving the estimated ultimate recovery (EUR) of the assets, increasing the economic viability of the operations. Completion Methods Compared The first objective was to determine which major completion function had the most effect on production and then on cost. Completion equipment is a major function of this aspect, and currently there are two main completion methods being used in the two plays: OHMS completion systems and CCPP methods. The main difference between OHMS and CCPP systems is when the liner is picked up and run into the lateral section (Snyder and Seale 2011). In OHMS completion systems, the lateral section is left as uncemented, and fracture ports and isolation packers are run into the well as part of the liner. The well is stimulated in one continuous pumping operation, using size-specific actuation balls to open the fracture ports and provide isolation inside the liner between stages. In CCPP completions, a liner is run into the wellbore and cemented in place. The cement provides annular isolation, while a series of bridge plugs provide isolation inside the liner between stages. Several trips are required in and out of the wellbore to shoot perforation clusters in the liner and set bridge plugs for each stage.

Abstract The development of unconventional resources in North America has led to the implementation of a variety of drilling and hydraulic fracturing techniques. This paper reviews completion diagnostic data from over 50 wells in the Anadarko and Williston Basins that were evaluated by a multidisciplinary team. Production analyses were conducted in conjunction with the diagnostic data to further qualify the effectiveness of different completion practices. Stimulation diagnostics including proppant tracers, microseismic data, and permanently installed fiber optic sensors are available to assist with identifying fracture growth both within and outside of a targeted interval. Wells in this study will utilize proppant tracers for the evaluation of stage coverage and isolation effectiveness. This paper specifically focuses on isolation techniques used during hydraulic fracturing of uncemented multistage horizontal wells, including swellable packers, and single and dual-element hydro-mechanical packers. Stimulation coverage and zonal containment for these isolation techniques were evaluated, and the results demonstrate how different isolation techniques can affect production. This study shows how operating conditions may also affect the integrity of certain isolation techniques, as results for the most effective isolation techniques vary by basin. These operating variations, among others, are examined in this paper as a possible contributing factor for the loss of annular isolation and corresponding production decreases. Isolation techniques are often implemented in drilling and completion programs with insufficient data or field trials. Most of these decisions are made based on perceived cost optimization rather than the overall completion effectiveness and performance of the well. This study is the first of its kind using a macroscopic analysis of completion diagnostics and production data over a large data set for the evaluation of isolation techniques.

Abstract This study compares the performance of openhole packer to cemented liner completion systems across 30 single-lateral horizontal wells by one operator in the northern Montney gas resource play. With up to 5,400 Tcf of initial gas in place, the Montney Formation rivals the Marcellus play both in size and scope of future development. Our data demonstrates that the benefits of openhole completions relative to cemented liner completions include an average 25% increase in IP30 rates, an average increase from 7 to 10 Bcf in expected ultimate raw gas recovery per well, an average 13% decrease in stimulation period costs, plus an average 36% decrease in stimulation operating time (days), all on an unadjusted basis. When adjusted for total proppant placed or total fluid pumped on average per completion, the relative benefit of openhole systems ranges from 6% to 31% depending on the test metric selected. Surface-array microseismic monitoring was conducted over two of the study wells, one involving a cemented liner system and one involving an openhole system, with the goal of understanding the stimulation patterns relating to each completion style. Focal mechanism solutions were calculated for individual microseismic events and displayed on a series of failure plane crossplots segmented by lateral distance from the stimulation stage mid-point. Our evaluation focuses on event counts and magnitudes, plus event clustering relating to failure style. This paper presents the first published case study to apply this new method of hydraulic fracturing analysis. The openhole stimulation in our study area is characterized by a large event population, exhibiting a moderate cluster of high-angle failure initiating in the near-well region. Event clustering strengthens as lateral distance from the wellbore increases. The cemented liner stimulation is characterized by fewer events which exhibit weak clustering at moderate angles of failure across all distances, but particularly in the critical near-well region. Together with the observed magnitude histograms, these patterns clearly indicate different styles of rock stimulation. We infer that the openhole completion benefited from constructive interference during fracturing due to direct pumping access to multiple random initiation points afforded by the open annulus. In contrast, the cemented liner completion fails to develop a comparable complexity because the limited entry perforation spacing restricts constructive interference during the stimulation process. Debate continues regarding the advantages of openhole vs. cemented liner completions. This paper presents an example of another technique to evaluate and compare stimulation patterns during hydraulic fracturing. The results from this study support the continued application of openhole completion systems to the Montney play in northeastern British Columbia.

Abstract Turkey has significant oil and gas reserves that have not been fully developed. This paper will highlight the planning, execution, challenges and production benefits of the first installations of horizontal open hole multistage completion systems in the Şelmo field. Located in southeastern Turkey and north of the prolific Zagros fold belt, which encompasses the oil fields of Iran and Iraq, Şelmo is the second largest oil field in Turkey by cumulative production, with an estimated 600 MMbbl of oil in place. An operator has recently started redeveloping the field targeting the Middle Sinan Dolomite zone by drilling horizontal wells. Matrix acidizing is a method of stimulating carbonate reservoirs for oil and gas production. The acid treatment creates conductive flow channels which transport reservoir fluids from within the formation matrix directly into the wellbore. In matrix acidizing of carbonate reservoirs, accurate acid placement is a major challenge because the acid tends to flow preferentially toward the highest permeability areas. This can result in overstimulation at these intervals leaving the lower permeability regions untreated. A significant percentage of matrix acidizing treatments do not meet expectations because of improper job design. In some cases, increased water production is observed due to preferential stimulation of high permeability sections associated with water. This paper will provide an in depth understanding of acid stimulation of carbonate formations with both single and limited entry open hole multistage systems that can be applied to carbonate reservoirs worldwide. The operator designed a pilot project including four horizontal wells in the Şelmo field; two wells were completed using single entry open hole multistage completion systems and the other two using batch stimulated limited entry open hole multistage completion systems. In the single entry systems, there is only one injection port per stage while in the limited entry systems, multiple injection jets are used. The jets enable controlled injection and leak off for effective flow of acid into the entire section of the interval. The designed treatment is thereby placed at an optimal rate and pressure along the stage length, maximizing the development of conductive channels throughout the entire stimulated reservoir. Results of the pilot indicate a successful stimulation and a significant increase in production from all four horizontal wells compared to offset vertical wells. With the success achieved from the first horizontal open hole multistage completion systems in Turkey's Şelmo field, the operator plans to complete more wells using these systems to exploit its assets. The success of this project demonstrates the applicability and benefits of using open hole systems for effective matrix acidizing of carbonate reservoirs around the world.

Abstract The Montney Formation Resource Play, which straddles the border between the Canadian provinces of British Columbia and Alberta, is considered by many to be one of the largest natural gas resource plays in North America. Original gas-in-place estimates for the Montney range from a minimum of 80 tcf to as high as 700 tcf. Despite horizontal, multistage stimulation being common practice to effectively exploit tight gas sand and shale reservoirs, determination of the optimal methodology and identification of the parameters that affect optimization have yet to be fully understood. This paper compares two different multistage hydraulic fracturing technologies applied in the Lower Montney Formation: cemented liner and openhole multistage system (OHMS) completions. In-depth analysis was performed on field data from 15 wells divided into two separate geographical areas within the same field. Comparisons included production analysis, lateral lengths, number of stages, stage spacing, proppant volumes, and pump rates. Additionally, operational time and cost comparisons on a per well and per stage basis for both technologies were determined. Based upon the field data analyzed, the application of OHMS completion technology is appropriate for the Lower Montney in the region of the play studied. Application of this technology for the wells selected in the two study areas resulted in both greater initial production rates and overall cumulative production than cemented liner completed wells. Additionally, less time was required to perform the fracture stimulation job when using OHMS technology as compared to cemented liners. Both the average total cost of completion and average cost per stage in conducting cemented liner jobs was higher than employing OHMS completions.

Abstract Open hole, multi-stage (OHMS) fracturing systems were introduced in 2001. Since then, this technology has been credited with unlocking oil and gas reserves around the world that were previously dismissed as unavailable or uneconomic, enabling companies to maximize production in tight rock formations and mature oil fields. OHMS systems have been run in every type of formation from the much heralded shale gas plays in North America to the massive carbonate formations in Saudi Arabia and have also been used in offshore wells in the North Sea, Black Sea and West Africa. This paper focuses on the open hole packer used in OHMS systems to generate the annular compartmentalization necessary for effective multi-stage stimulation and production. This packer is a dual element, hydraulic-set, mechanical (DHM) packer and provides reliable open hole isolation with various benefits compared to swellable, inflatable and other mechanical packers including: 1) Reduced torque and drag due to their short length (average 5 ft) with only two short sections of rubber with a minimum running outside diameter, 2) Creation of two independent sealing points via dual elements, which together act like a single, 3 ft long seal with redundant sealing, 3) No need to formulate them for specific downhole fluids or wait for them to swell, 4) No thermal contraction such that the seal is not lost during stimulation, and 5) The rubber element does not reduce its durometer rating when set. Laboratory testing and field applications of the DHM packer are presented including HPHT, multi-laterals, proppant fracturing and acid stimulation with on and offshore case histories incorporating stand alone screens, acid jets, fracture ports and combinations thereof.

Abstract The Bakken formation in the Williston Basin has received increasing recognition over the past five years due to the ability of operators to consistently deliver wells with prolific production results and extraordinary economics. This has been made possible by the steady advancement of technologies associated with drilling and completing horizontal wells in addition to the majority of the wells being located in the core of the formation where reservoir pressure gradients are at their maximum. The magnitude of the Bakken formation means that the majority of the acreage is considered intermediate or outlying from the core presenting the challenge of making the normal pressured reservoir in these areas economically viable. This paper presents a unique combination of drilling optimization with advanced open hole, multi-stage fracturing system (OHMS) technology, which together are pushing the envelope for continued improvement in operational and production efficiencies. This paper will present directional drilling advantages and artificial lift benefits using rotary steerable technology and advancements in OHMS allowing increased stage density for production optimization. Through the proper implementation of these leveraging technologies, the time to drill and complete a well in the Bakken has been reduced and fracture stage density has been increased over current standards igniting a continuing trend to increase stage density in the Bakken formation as a result of significant gains in sustained recovery. This systematic approach to streamlining the drilling and completion programs has resulted in notable improvements in the economic metrics for the play. The technological progress presented has resulted in a dramatic shift in the industry in terms of drilling and completion in the Bakken formation and the techniques described can be adapted and applied in virtually any resource play.

Abstract The industry has made a very quick turn toward both unconventional reservoirs and horizontal, multi-stage fracturing. Some industry experts have begun to question the effectiveness of recoveries in these massive reserve assets. A notable formation in these discussions has been the Barnett Shale, where a variety of methods and technologies have been used to fracture stimulate horizontal wells. In fact, much of the learning curve for completion practices has come from experimental work in this unconventional play. From 2004 through 2006, a new, open hole, multi-stage system (OHMS) completion technology was run in Denton County, Texas. Using publically available data from the past five years, this study contrasts long-term production results from OHMS completed wells and wells completed with cemented casing. The data set for OHMS fractured wells compared to the data set for cemented fractured wells indicates that open hole wells, on average, performed better. Significantly, no failures or shut-in periods were observed for the OHMS wells. This establishes the viability, reliability and effectiveness of this technology for the long-term life of wells not only in the Barnett, but for performance enhancement in other shale plays. Substantial amounts of money are currently being spent to rapidly develop resource plays similar to the Barnett worldwide. Based on short-term results using current completion methods, predictions for ultimate recoveries may be overestimated. This paper evaluates the effectiveness of current completion practices by contrasting two methods in terms of production, economics, operational efficiency, and best fracturing practices to determine whether the completion method can affect overall well performance and long-term recovery.

Abstract Over the last several years there have been many technical developments in horizontal completion methods. These developments have been designed to better stimulate the entire horizontal interval. For cased and cemented applications, composite plugs have provided the ability to segment the horizontal wellbore into sections and divert the stimulation as designed. However, the process of setting a plug on coiled tubing (CT), perforating, stimulating and then repeating the process for the required number of stages to optimize production and then running back in with CT to remove the plugs can take weeks to complete. For open hole applications, horizontal stimulations have relied solely on bullheading in stages in an attempt to generate multiple fractures. This has proven in many cases to only stimulate certain sections of the wellbore leaving much of the horizontal section unstimulated. A new completion system has been deployed in over 300 wellbores in various producing formations, such as sandstone, limestone, shale, dolomite and coal. This system uses a series of mechanical open hole packers deployed on the production liner with fracturing or stimulation ports located between the packers that allow for stimulation in each desired interval. Without the requirement of cementing the liner in place, all the problematic issues associated with cementing are eliminated. Additionally, the use of mechanical packers provides positive mechanical diversion at high differential fracturing pressures. The system has also been designed, so all of the fracturing or stimulation treatments along the horizontal wellbore can be pumped in one continuous operation, thus minimizing the associated risks and optimizing the efficiencies of both the personnel and equipment needed to perform the work. This paper will detail the operational efficiencies and reliability of this novel completion system, as well as analyze the cost benefits and production increases that have been noted.