Haider, Bader Y.A. (Kuwait Oil Company) | Rachapudi, Rama Rao Venkata Subba (Kuwait Oil Company) | Al-Yahya, Mohammad (Kuwait Oil Company) | Al-Mutairi, Talal (Kuwait Oil Company) | Al Deyain, Khaled Waleed (Kuwait Oil Company)
Production from Artificially lifted (ESP) well depends on the performance of ESP and reservoir inflow. Realtime monitoring of ESP performance and reservoir productivity is essential for production optimization and this in turn will help in improving the ESP run life. Realtime Workflow was developed to track the ESP performance and well productivity using Realtime ESP sensor data. This workflow was automated by using real time data server and results were made available through Desk top application.
Realtime ESP performance information was used in regular well reviews to identify the problems with ESP performance, to investigate the opportunity for increasing the production. Further ESP real time data combined with well model analysis was used in addressing well problems.
This paper describes about the workflow design, automation and real field case implementation of optimization decisions. Ultimately, this workflow helped in extending the ESP run life and created a well performance monitoring system that eliminated the manual maintenance of the data .In Future, this workflow will be part of full field Digital oil field implementation.
Shale drilling for both natural gas and hydrocarbon liquids has increased dramatically in North America over the last several years. Shale oil and gas deposits are known to exist all over the globe including Australia and the rest of the Asia Pacific. This paper discusses the requirements for drillpipe in shale drilling applications along with a review of some of the challenges and problems associated with the drillstring in these critical applications. Most wells are horizontal with long departures. Typical wells in the Balkan Shale are 17,000 ft MD, 11,000 ft TVD with a 6,000 ft horizontal reach. Drilling these wells puts huge demands on the drillpipe and rotary shoulder connections and pushes the drilling equipment and rig crews beyond the requirements of typical onshore well construction projects. Many, if not most, of the shale wells require advanced design, double shoulder connections (DSC) on the drillstring to provide the enhanced torsional strength and streamlined connection dimensions required to effectively drill these prospects. The paper presents connection design solutions along with considerations for safe and efficient running procedures. Although, the advanced DSCs are designed to be transparent to normal drilling operations, compared to standard API connections, some problems have been encountered. The paper addresses these running and handling issues and provides guidelines to mitigate these problems. Excessive tool joint and drillpipe body wear have also been encountered in several shale plays. This is discussed, along with recommendations to limit wear. Stick-slip has created drillstring problems on several wells. Stick-slip can cause damage to the drillpipe and, in the extreme, downhole connection back-offs have occurred. The paper looks at aspects of case histories to illustrate these issues and provides lessons learned to improve shale drilling operations in North America, the Asia Pacific and other regions of the world.
Horizontal directional drilling combined with multi-stage hydraulic fracturing have created a robust drilling environment for exploiting shale natural gas and hydrocarbon liquids throughout the U.S.A., see Figure 1. It is also well known that shale oil and gas deposits are also present throughout the rest of the world including Australia, New Zealand and various regions of the Asia Pacific, see Figure 2. Expectations are strong that more shale and other unconventional sources will be explored outside of the U.S. as new sources of hydrocarbon energy resources are required to meet increasing worldwide demand. Shale drilling activity in the U.S. has increased dramatically over the last several years. Shale drilling applications can be very demanding for the drilling rig, equipment, crews and technical professionals involved in the endeavor. The learning curve has been steep and there are clearly more technical challenges to be addressed and overcome as more areas are explored. Of course, there is a great deal of variation between the characteristics of different shale fields and not all fields create the same intensive challenges or technical hurdles. Nevertheless, a great number of the fields currently being explored and produced offer significant challenges. In many of the fields the gas and/or liquids are located at relatively deep TVD's; with TVD's from 10,000 ft to 14,000 ft not being uncommon. As mentioned above, the wells generally include a horizontal section that can extend up to 6,000 ft and beyond. A typical shale well schematic is depicted in Figure 3. The wells can also have high bottom hole formation temperatures that in some cases approach 375 °F. In many areas the formations are highly abrasive creating friction and wear related issues.
Drilling the hard/abrasive Travis Peak/Hosston and Cotton Valley formations in East Texas/North Louisiana creates a distinctive challenge for polycrystalline diamond compact (PDC) bits. Conventional PDC cutters fail quickly due to abrasive wear/spalling and/or delamination of the diamond table. Most bits are typically pulled in poor dull condition graded 1-2-WT or worse. The situation has caused stagnation in PDC performance and limited additional gains in total footage and rate of penetration (ROP). Recent scientific studies have indicated that thermal fatigue of the diamond table is the main contributing factor leading to cutter failure and is restricting further advancement of PDC drilling in East Texas and other hard and abrasive applications. To improve cutter performance the industry must:
1. Manufacture a cutter to resist abrasive wear and retain a sharp edge for an extended amount of footage
2. Reduce/maintain temperature at the cutter edge to minimize thermal fatigue
To accomplish the objectives, engineers refined and implemented several new processes to increase abrasion resistance and maintain temperature at the cutter tip. This technology platform includes:
1. Enhanced High Temperature/High Pressure (HTHP)sintering process
2. Refined post-pressing process to improve thermal stability
3. Optimized hydraulics to maximizing cutter cooling
In laboratory experiments, the next generation O2 cutter has demonstrated approximately 15% improvement in resistance to abrasive wear compared to the previous generation of premium cutters (O1). Laboratory tests also confirm that optimizing cutter cooling has enhanced the life of the new shearing element. In East Texas field tests, PDC bits equipped with the new cutter and optimized hydraulics have achieved an average ROP increase of approximately 25% while producing improved dull bit condition. These new technologies are expected to have a positive economic impact in the East Texas/North Louisiana Haynesville shale play and in other hard and abrasive applications worldwide.
ABSTRACT Anytime sucker rods contact the inner diameter of production tubing in corrosive wells, wear accelerated corrosion will result. The resultant damage is likely to be greater than the sum of the two factors acting individually. Experience tends to agree that minimizing the corrosion component with corrosion inhibitors minimizes the damage, and that continuous application of the inhibitor is more beneficial than batch application. This paper follows laboratory development and field testing of a batch applied corrosion inhibitor designed to have added benefit for this task. In the laboratory linear polarization resistance evaluated inhibition and standard lubricity tests evaluated wear characteristics. Corrosion coupons, manganese ion in the water from this sour field, and failure records evaluated field performance. Coupons detect the corrosion component, and manganese ions reflect total corrosion-plus-wear occurring in the well. The ratio of these to measurements before and after application evaluated success prior to any failures occurring. INTRODUCTION Exact details of the mechanism of wear accelerated corrosion are certain to be quite complex. 1 Just wear itself and lubrication are complex enough. 2, 3 Electrochemical corrosion due to dissolved gases and volatile organic acids in the oilfield has been the subject of many studies. 4 Many times an active wear area in a corrosive media becomes anodic to the film area, giving rise to galvanic corrosion acceleration. 5, 6 Mechanistic similarities probably exist for erosion accelerated corrosion. 7, 8 Rather that explain all the facets of the mechanism, this paper outlines attempts to minimize wear accelerated corrosion with corrosion inhibitors. Earlier studies have shown that this effort can provide benefits. 9, 10 The reason that sucker rod strings sometimes contact the inner diameter of production tubing can be due to crooked zones in the hole, or to intentionally deviated holes.
Wells are now routinely drilled both in deepwater and on land to depths that were previously considered impossible. In these environments, casing design is critical to safely and successfully drilling and producing wells, and unexpected casing wear can result in significant costs or even the loss of a well. As part of a successful casing design strategy, the engineer must assess the maximum permissible casing wear required to maintain casing integrity. Then, steps must be taken to ensure that casing wear thresholds are not exceeded.
Casing wear models use the number of drill string revolutions and contact force between the drill pipe and casing to calculate wear. The contact force is calculated using the dog-leg severity within the well, with the maximum dog-leg severity often determining the location and extent of the most severe casing wear. There is often a large discrepancy between predicted and actual casing wear because of survey quality and inaccurate estimates of dog-leg severity and total revolutions. These discrepancies result in predictions of contact force and drill string revolutions that are in error by 50% or more.
To improve the accuracy of casing wear models, an extensive database was created from a wide variety of wells with measured depths greater than 13,000ft. The database results in a statistically based model for determining dog-leg severity within vertical, build, and tangent sections, as well as total drill string revolutions at various levels of confidence to bound average and maximum expected contact force and casing wear.
Case histories compare measured wear with predictions of casing wear based on original well data and the statistically based model. The case histories also demonstrate the effect of various drilling parameters on casing wear, and evaluate the effectiveness of non-rotating protectors in preventing casing wear.
The goal of this project was to more accurately quantify casing wear risk by improving casing wear analysis accuracy. To do this, data from a large number of wells was analyzed to generate probabilities for dog-leg severity in common well types and also correlate those to actual backmodeled casing wear factors. The results will allow an engineer to analyze what the expected casing wear might be for an average (P50) horizontal well, and then evaluate the maximum expected wear for a 1 in 10 case (P90), 1 in 20 case (P95), or 1 in 100 (P99) case.
All casing wear software, and torque and drag software as well, use a directional survey to determine the side force or contact force between the drill string and wellbore. These points within a directional survey can be a representation of a planned well path, or it can be taken from actual downhole measurements. The survey points are then connected into a single line representing a best approximation of the wellpath with the information given.