Cheatham

SPE Peer-Approved Papers in the Year 2020

How will readers access our journals 8 years from now?

To address this important question, let’s take a look at a brief history of SPE's peer-reviewed publications, with thanks to Glenda Smith, SPE Senior Manager, Technical Publications.

In the early years of the Society of Petroleum Engineers, the Journal of Petroleum Technology (JPT) published full-length, peer-approved (PA) papers. In 1961, the SPE Journal (SPEJ) was created to publish more scientific, fundamental research PA papers, and JPT began handling only the more practical PA papers. This format continued for 25 years until 1986, when SPE made three major changes in publishing peer-approved papers. First, JPT stopped publishing peer-approved papers of any type. Second, discipline-based journals were launched--including SPE Drilling & Completion. And third, SPEJ was discontinued. In 1996, SPEJ would be reborn to handle PA papers of a more fundamental research nature. The next major change occurred in 2005, when online versions of the journals were added.

We see there has been significant change over the last 50 years. Today we are in a major revolution in information/communication technology. Therefore, the question is: What changes should SPE make to best serve its members in light of the ongoing transformation?

As we consider this question, there is a troublesome trend worth noting. In recent years, the number of subscribers to SPE journals has essentially remained constant despite the large increase in membership. This fact indicates it is time to reevaluate SPE journals from the ground up. Granted, when one considers this trend, there are some obvious contributing factors. First, the subscription price has gone up significantly in the past few years as print media everywhere have struggled to remain economically viable. Second, there is an increasing usage of the number of papers downloaded from OnePetro (many companies have corporate memberships) that may be hurting subscriptions.

Both of these factors undoubtedly affect journal subscription, but there is perhaps a more important cause. SPE members are increasingly accessing technical papers from mobile devices, such as iPads, other tablets, smart phones, and laptops. Some print media have already ceased to exist, and the threat to the existence of all remaining print media grows each day. Furthermore, the rate of change of the shift to new and different ways of accessing media is accelerating. Remember, 8 years ago SPE had no online access to its journals. Imagine today how strange it would seem if we were unable to read a technical paper using online access (that may not be your preferred method of access, but everyone takes it for granted that it is available today). This shift toward electronic media is affecting journals in all industries, not just SPE. The revolution in journal access is happening today right before our eyes, and it is worthwhile to consider how readers will access our journals 8 years in the future.

The problem is complex. As a society of engineers, we should try to solve it like a complex problem. First, appropriate and accurate data must be gathered and analyzed to determine root causes of the problem. Then, options to overcome these obstacles should be developed and analyzed to determine the optimal way forward. Finally, changes must be implemented. This is exactly what SPE is doing. Over the next year, this problem will be addressed at the request of the SPE Board of Directors. During this time, you may be called on to provide input. But even if you are not contacted, please help your society solve this important problem by providing your thoughts and critical comments! There will probably be major changes in the way you receive peer-reviewed papers in the near future and beyond. We need all hands on deck to make sure we get these changes right.

Now to the papers. This issue contains 13 papers and a bonus reprint.

• 1 on drilling-engineering training with directional drilling examples
• 2 on well control and managed-pressure drilling
• 1 on drillstring dynamics
• 1 on casing drilling
• 4 on completions
• 1 on formation damage
• 2 on well integrity
• 1 on wellbore strengthening
• 1 classic on horizontal drilling

Drilling Engineering Training With Directional Drilling Examples

Our first paper is a must-read. Simple Engineering Applications Recycled as Effective Training Aids focuses on drilling-engineering training at the intermediate level, which is an important issue as the Big Crew Change moves into warp speed. Directional drilling examples are used to illustrate key points, but the author points out that the method can be applied to other applications, such as casing design, hydraulics, and hole cleaning. There is much to like about this paper, but what I like most is the author’s passion for engineers to understand the fundamental concepts that underpin sophisticated software-engineering-analysis models and software. The examples show how engineers can solve simple problems to gain critical insights to more complex problems and help interpret high-tech (and sometimes even black-box) computer programs. Simple problems, such as the ones described in this paper, are essential for validation of software-engineering applications because they can be solved using exact analytical solutions. This leads to a crucial philosophical point: Advanced engineering software applications are a tool and should be used accordingly. In the hands of a well-trained, experienced engineer, these tools are powerful extensions of their own expertise. But the same software can be useless--or worse, counterproductive--in the hands of someone who uses it as a substitute for engineering skills and experience. The author eloquently explains his philosophy by stating that (1) teaching methods should instill curiosity and encourage critical assessment of the models and methods used, and (2) students should explore the physics in both mathematical and qualitative terms. Bravo! This philosophy is one that I embrace and fervently try to teach to the bright young engineers with whom I am fortunate to work. I really like this paper and highly recommend it to all readers, particularly YPs!

Well Control and Managed-Pressure Drilling

Managed-pressure drilling (MPD) offers opportunities to improve drilling performance and safety, which is a highly desirable combination. Our next paper takes a significant stride forward to achieve these goals. A Proposed Method for Planning the Best Initial Response to Kicks Taken During Managed-Pressure-Drilling Operations is the second paper published in SPE Drilling & Completion from a research consortium focused on providing the basis for comprehensive, reliable well-control procedures for MPD operations equivalent to the industry standard procedures used in conventional drilling. The first paper published by this research consortium appeared in Volume 26, Number 2, in the June 2011 issue. The current paper proposes a method for preselecting the best initial response when a kick is taken during constant bottomhole pressure MPD operations.

Fundamental research on gas kicks is an important topic. A Dynamic Model of Percolating Gas in a Wellbore describes a simplified two-phase gas model. The authors state that their objective is to model gas percolating up a wellbore without resorting to the use of partial differential equations. They were motivated by other simplified models, including one published in the last issue of SPE Drilling & Completion (Kaasa et al., Simplified Hydraulics Model Used for Intelligent Estimation of Downhole Pressure for a Managed-Pressure-Drilling Control System). The authors show how to use wired drillpipe distributed pressure measurements and an unscented Kalman filter with their simplified two-phase gas model to estimate liquid-holdup profile as a gas kick is circulated out of the well. Performance of the model and method of estimation are compared with results from a state-of-the-art simulator (OLGA). Results show it is possible to use noisy wired drillpipe measurements to successfully estimate liquid-holdup profile.

Future work will augment the model to include fluid compressibility, non-Newtonian fluids, and inclined wells. (Editor's note: liquid holdup is the fraction of the cross-sectional area occupied by the liquid in the pipe or annulus carrying the two-phase gas and liquid flow. Liquid holdup is important because it has a major effect on accurate prediction of pressure losses in two-phase flow. For more information, see http://geocities.ws/abouelsaoud/productionstorage/liquidholdup.pdf).

Drillstring Dynamics

Our next paper is innovative and practical. Quantification of Drillstring-Integrity-Failure Risk Using Real-Time Vibration Measurements combines conventional MWD vibration sensors in a single location in the drillstring with a new method of data analysis. The new calculation is called the characteristic intensity and is derived from seismic ground-motion-intensity calculations. It takes into account both the cumulative vibration and the length of the run. The paper provides comparisons to standard measures of data analysis, such as RMS acceleration and peak acceleration, for field runs in 17 ½-in. and 12 ¼-in. hole sizes. For the cases studied, the characteristic intensity identified approximately 80% of the drillstring-integrity failures. The paper concludes that the new method allows the differentiation of high-risk scenarios by using only vibration data from the run. As the authors state, this result was obtained despite the fact that fatigue or wear of drillstring components before a run are unknown and vibration sensors were located at a single position in the drillstring. They conclude the results seem to indicate that the main contributor to the actual integrity failures is the fatigue accumulated for any given bit run.

Casing Drilling

The challenges of transferring technology to a new geographical area can be formidable. This paper details an excellent case history for the introduction of casing drilling to a new area. Casing While Drilling (CwD): A New Approach To Drilling Fiqa Formation in the Sultanate of Oman--A Success Story tells the story of how wellbore-instability problems were overcome in two fields. Critical success factors were appropriate engineering planning, careful selection of casing drilling components and personnel, and implementation and monitoring of real-time drilling efficiency and optimization tools. The key performance indicators of reducing overall drill/case time and cost were used to demonstrate the successful implementation of casing drilling in these fields in northern Oman. Readers who are interested in casing drilling or in reading about how technology is effectively transferred to a new field or area will enjoy this paper.

Completions

The first of four completions papers in this issue presents An Improved Technique for Interpreting Perforating-Flow-Laboratory Results: Honoring Observed Cleanup Mechanisms. It discusses traditional perforating laboratory experiments (API RP-19B, Section 4) that yield key results that are required inputs to downhole flow simulators. The paper develops new methods for measuring and interpreting coreflow efficiency. The new method enables more realistic treatment of effective tunnel flowing length, diameter, crushed-zone thickness, and crushed-zone permeability. This work accepts the existing conventional skin and downhole-inflow models as a valid framework for the time being. The authors present a coherent methodology of interpreting laboratory data for the purpose of generating the required inputs to the skin models. In addition to improving the treatment of perforation damage within the existing framework, the discussions in this paper also pave the way to develop new models that will extend beyond the current 1D radial inflow simplification. The authors recommend this workflow should be considered for inclusion in any revisions to Section 4 testing protocol.

Many casing- and screen-damage incidents have been reported in deepwater oil and gas fields in the Gulf of Mexico and other locations around the world. Casing- and Screen-Failure Analysis in Highly Compacting Sandstone Fields reviews historical casing/well-failure events in five wells in a highly compacting sandstone field and performs a comprehensive geomechanics analysis of various casing-damage mechanisms (tension, axial compression, shear, and bending) related to large reservoir depletion. A 3D nonlinear finite-element model is developed for simulating stress changes in the overburden and the reservoir intervals and evaluating the effect of lithological anomalies on casing stability. The numerical-analysis results presented in this work help engineers understand possible casing and screen deformation and failure mechanisms experienced in highly compacting sandstone fields. On the basis of the study findings, completion design guidelines are presented to avoid or mitigate compaction-induced casing damage in both the overburden and reservoir intervals.

Sand-control technology commands much attention in our journal, and it is the subject of our next paper that offers a highly innovative solution to an old problem. Pumping a gravel slurry between a downhole screen and the rock matrix has been used to prevent production of undesirable solids or sand from the formation in traditional oil and gas completions. Recently developed expandable technology attempts to eliminate this operation by expanding metallic sand-control screens against the wellbore. However, a problem with this process is borehole irregularity. It is desirable to have a smart downhole screen structure that is capable of self-expanding and conforming to the borehole surfaces in certain downhole conditions. In-Situ Mechanical and Functional-Behavior Characterization of a Shape-Memory Polymer for Sand-Control Applications documents development and extensive laboratory testing of an advanced shape memory polymer structure that offers breakthrough performance for sand-control applications. This study used a high-pressure/high-temperature in-situ mechanical-test system and test method to characterize the in-situ hot-wet mechanical and functional behavior of the shape memory polymer foam, including deployment and contact-pressure development functional properties, and compressive and time-dependent stress-relaxation and creep mechanical properties. Study results are used to establish the operational window of shaped memory polymer screen as a sand-control solution. The new technology reported in this paper is certainly exciting. Presumably, the next step is field trials.

Knowing the exact flow allocation for each controlled zone is important for well optimization and the management of an intelligent well system (IWS). Transferring Intelligent Well System Triple-Gauge Data Into Real-Time Flow Allocation develops a comprehensive hydraulics model to address this topic. This paper discusses a recent application of the model to estimate the flow allocations of an existing two-zone deepwater IWS oil producer that began production in 2007. A total of 1,362 daily triple-gauge data points are available for this study, where pressure and temperature data indicate that the well was flowed in multiphase downhole conditions for a large percentage of its production life. Verification was completed by comparing the predicted flow-allocation results with this well’s measured total rates and daily allocation rates. These comparisons showed a good match between the predicted results, measured data, and the available reservoir study results. This paper is very interesting and recommended to readers who are considering use of intelligent wells or who want to stay abreast of the latest developments in this area.

Formation Damage

Most filter-cake models in the literature assume homogeneity in the radial direction. Characterization of Filter Cake Generated by Water-Based Drilling Fluids Using CT Scan shows that the filter cake is not homogeneous, but instead consists of two layers of different properties. The results obtained from the computed tomography scan showed that the filter cake in these laboratory studies contained two layers with different properties. One layer was close to the drilling fluid, which had an average thickness of 0.1 in., while the second layer close to the rock surface had an average thickness of 0.06 in. Both the porosity and permeability of the layer close to the drilling fluid were zero, while the porosity of the layer close to the rock surface ranged from 10 to 20 vol% and the permeability of this layer was nearly 0.087 μd. Scanning electron microscopy results showed that the two layers contained large and small particles, but there was very poor sorting in the layer close to the drilling fluid, and led to zero porosity in this layer. Previous models underestimated the thickness of the filter cake by almost 50%. A new method was developed to measure the thickness of the filter cake, and various models were screened to identify the best model that can predict our permeability measurements.

Well Integrity

In the post-Macondo world, well integrity has received much attention. But what exactly does "well integrity" mean? One definition of well integrity is "the application of technical, operational, and organizational solutions to reduce the risk of an uncontrolled release and/or unintended movement of well fluids throughout the life-cycle of a well" (NORSOK Standard D-010, Rev 3, August 2004). Our next paper, Assessing Well-Integrity Risk: A Qualitative Model, describes a well-integrity risk-assessment model that has proven to be successful for indentifying and ranking well-barrier-failure risk in a well, a group of similar wells, or an entire well portfolio. The results from the assessment allow the risks to be ranked so that areas of highest risk are identified and can be monitored and/or mitigated properly with limited resources. The asset can use the risk-assessment results as a reference for a well-integrity program to reduce risk from well operations and potential well-integrity problems on a routine basis.

Cement sheath is a key element for maintaining well integrity. In our next paper, the authors develop a mechanistic model to simulate the various modes of loss of cement-sheath integrity after the cement has been placed in the well. Use of a Mechanistic Model To Forecast Cement-Sheath Integrity aims to evaluate the risk that cement sheaths could represent to leakage pathways because of the cement becoming damaged or debonding at one of the boundaries. This paper first summarizes cement behavior as a solid, and then uses data presented in the first part to show that loss of cement-sheath integrity not only depends on cement properties but also on the well architecture and well history. The model presented here is thoroughly explained and is of interest to other researchers focused on cementing or well integrity.

Wellbore Strengthening

Twenty years ago, the first paper was published on wellbore strengthening. Fortunately for readers of SPE Drilling & Completion, our next paper was written by two of the same authors as that pioneering work. In recent years, various methods of wellbore strengthening have been proposed, such as well cooling, stress cage, and tip screenout of induced fractures. Parametric Analysis of Wellbore-Strengthening Methods From Basic Rock Mechanics presents a set of analytical equations developed for these three well-known wellbore-strengthening methods. It also provides information about the strengths and limitations of each method. Finally, an updated set of equations based on previous works by the authors are provided to make analysis of wellbore-strengthening methods easier to implement.

Classic SPE Drilling & Completion Paper

This issue closes with the reprinting of a classic paper that helped change our industry. In this issue, we have chosen Drilling the Cold Lake Horizontal Well Pilot No. 2 by R.R. MacDonald. This paper first appeared in SPE Drilling Engineering Vol. 2, No. 3, in September 1987. (SPE Drilling Engineering was the precursor of SPE Drilling & Completion.) It was the first paper on horizontal drilling published in our journal.

Since this paper was published 25 years ago, horizontal drilling has become a mainstay technology. The recent boom in unconventional reservoirs, such as shale gas and liquids, would have been impossible without horizontal drilling. Nowadays, it is routine to drill dozens or even hundreds of horizontal wells in an unconventional field. How far the industry has come in a quarter of a century!

This paper is important for the historical achievement it documents. In addition, the story itself is worth reading by today's engineers, both young and old. It clearly describes the extensive engineering work performed to identify and address the key problems that were anticipated: hole drag (and associated drillstring buckling) and directional-surveying accuracy (and wellbore placement). Then, a comprehensive account of the drilling of the well is presented, including significant changes to the plan during drilling. For someone like me who entered the industry a decade before horizontal wells first appeared on the scene, it is fascinating to read how such a disruptive technology overcame limitations not only of equipment but also of people's thinking. I encourage you to read this prime example of superb drilling engineering--it will be worth it. Enjoy.

That wraps up this issue. On behalf of your entire Editorial Review Committee, thank you for your continued support of SPE Drilling & Completion.

Curtis Cheatham
cheatham@spemail.org