Mechanical descaling of iron sulfide scales in high angle non-monobore or horizontal open hole completion offer multifaceted challenges, especially when the reservoir is depleted. The history of the descaling program in carbonate gas wells in Saudi Arabia dates back to 2007. The program suffered several setbacks with operational complexities like stuck pipe, H2S generation (souring) during chemical dissolution and severe induced damage during reservoir isolation process. The depleted reservoir needs to be isolated to ensure full circulation during mechanical descaling process. The mechanical means of isolation with a bridge plug is not feasible due to the presence of FeS scale in the wellbore. The only isolation option available at the moment is CaCO3 chips bullheaded from the surface. Often the post-descaling and stimulation operation does not restore the original production, due to the heavy damage induced in the reservoir during isolation. This paper shares a successful descaling experience and best practices in a single lateral open hole well that was completed with 4-1/2-in tubing and 7-in liner, and had severe pressure depletion. A novel non-damaging visco-elastic surfactant based fluid was used to fill the open hole lateral and as base to support CaCO3 chips above it that prevented additional damage and allowed reservoir isolation for mechanical descaling, using high pressure coiled tubing and a jetting tool. A clean wellbore with no further induced damage made subsequent post-stimulation results very attractive. The paper also presents the production results of stimulation treatment performed after the descaling treatment.
Horizontal wells with extended reach drilled in Ghawar field awarded significant improvements, maximizing hydrocarbon production and attained ultimate recoveries. Over the life of those wells, intervention work is necessary to maintain hydrocarbon production by conducting remedial action, such as acid stimulation or water shut off. Necessary data for decision making can be obtained through running surveillance tools, which has proved to be a challenge, considering that these sensors will have to be deployed to total depth (TD). Many well intervention methods have been developed over time to overcome these challenges, such as coiled tubing (CT) and several types of wireline tractors. Wireline tractor technology has evolved to reduce time, cost and improve data quality and increase wellbore coverage. The use of a wireline tractor imposes fewer personnel on the job, much less equipment and less lifting of heavy loads resulting in a smaller footprint impacting the environment. In addition, the fast rig up of the wireline tractor and the running in hole (RIH) and pulling out of hole (POOH) speeds the highly deviated section, and cuts down on operating time. This paper will demonstrate horizontal logging experience gained from trial testing a new deployment solution for the production logging tool (PLT). A new generation of wireline tractors was utilized successfully to deploy the PLT for the first time in the Saudi Arabian field and showed exceptional performance. The tractor proved its capability to overcome different challenging wellbore conditions, such as rugosity, washouts, and high dogleg severity (DLS). Moreover, the tractor was able to efficiently pass through very short sections with large changes in the inclination and azimuth, This paper also covers the whole cycle of candidate selection, job design, execution challenges, post job evaluation, lessons learned and experience gained to optimize similar future jobs.
The implementation of extended reach horizontal wells in Saudi Aramco, and in the southern area of Ghawar field in particular, is being increased for production and cost optimization. Logging these wells is a challenge, as production profile of a horizontal section cannot be entirely recorded with conventional coiled tubing (CT). This is mainly because of friction forces between the CT and the wellbore, which cause CT to lock-up significantly shallower than total depth (TD). Although with availability of this limited technique, such as metal to metal friction reducer, still CT reach cannot be maximized effectively. This paper will describe a successful utilization of agitator tool with custom designed e-line bypass that helps CT maximize the coverage of the horizontal section for logging purposes. The agitator tool was incorporated into the Production Logging Tool (PLT) and bottom-hole assembly (BHA). It was activated by pumping to cause the CT string to vibrate, and subsequently reduce the friction contact between the CT and the wellbore to allow CT running beyond the normal lock-up depth. The tool was trial tested in an extended reach horizontal well which has a TD of 12,118 ft. The simulator was showing a predicted lock at 10,400 ft while a dummy run proved a lock-up point occurs at 10,800 ft without activating the agitator. The e-line agitator was activated while the well was flowing at a restricted rate which maximized the reach to the TD and reducing the friction coefficient by around 26%. Different conditions and parameters were conducted in order to understand the best performance of the e-line agitator tool. The implementation of the e-line agitator resulted in extending the reach of CT by an additional 1,300 ft and reaching TD. This additional reach was significant as the last part of horizontal section was contributing water. The production log has been reviewed and showed acceptable measurements. This paper will cover the whole cycle of candidate selection, job design, execution, post job evaluation, lessons learned and conclusion. Introduction Drilling strategy has been shifted from vertical to horizontal at most oil fields in Saudi Arabia due to proven advantages in optimizing production and cost. Even the existing vertical wells, they are being converted to horizontal to prolong their life, improve productivity index and delay water encroachment. Furthermore, the drilling strategy is being developed by drilling more complex wells, such as extended reach horizontal wells, to maximize reservoir contact. This type of well is widely implemented in Saudi Aramco, particularly in the Haradh area, which is located at the southern part of the giant Ghawar field. The extended reach horizontal well can be defined as a well with measured depth (MD) to true vertical depth (TVD) ratio that is equal to or greater than 2 (MD/TVD)1, 2. For this particular field, the horizontal well can be considered as extended reach when its horizontal section is equal to or more than 6,000 ft. These wells act as a challenge for most of the rigless well intervention operations, such as acid treatment and logging, using conventional coiled tubing (CT). The challenge came from CT limitation to cover the entire long horizontal section.
Saudi Aramco drilling strategy has shifted from vertical to horizontal due to proven advantages in optimizing production and cost. Evaluation of horizontal wells presents new challenges for the industry, especially with increasing water production. Therefore, it is important to determine the flow profile, water entry points and productivity index for remedial action, such as water shut off or selective stimulation. A new generation of production logging tools (PLTs) was introduced and utilized on some horizontal wet producers located in Saudi Arabia. The new PLT is comprised of arrays of spinners and sensors to log the entire cross section to describe precisely the horizontal flow regime. This PLT provides measurements of the downhole production and phases. A comprehensive evaluation was conducted of this type of PLT using different acquisition methodology and deployment methods to understand the best logging procedure. Therefore, one set of the spinners and sensors was attempted into two wells while two sets were attempted in the other two wells. Also, the PLT was deployed using two methods, which are coiled tubing (CT) and wireline tractor. Consequently, a group of lessons learned was gained, and the best logging procedure was established. The operation and interpretation results indicated that the production profiles obtained using this intelligent tool are reliable and accurate. This paper describes cases including planning, deployment, data acquisition, detailed analysis, results and lessons learned. A quality control of the data is also reviewed considering the importance of real time acquisition and validation of the information for future use in reservoir management or well intervention.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWater production is a major problem for any oil and gas field. If not properly managed, unwanted water production will seriously impact the economics of a project through lost hydrocarbon production, reserves recovery and ever increasing treatment costs. It may cause major economic and operational problems for several reasons. It requires increased capacity of water separation and handling facilities, decreases hydrocarbon production, and results in large amounts of produced water that need to be disposed in an environmentally friendly manner. Some fields in Saudi Arabia use water injection for reservoir pressure maintenance, which makes water production and handling a necessity even at a relatively early stage of some of these fields life cycle. As drilling technology advanced in the past years, horizontal wells became the norm in many fields managed by Saudi Aramco, especially in the giant Ghawar filed, the largest oil filed in the world. Some of these wells started cutting water, and as the water cut increased the need to perform rigless water shutoff was needed due to the high demand and high cost of workover rigs. This paper will highlight the methodology, equipment and procedure used in the first rigless horizontal WSO in South Ghawar area by Coiled Tubing (CT) intervention to isolate the water producing zone at the toe of the well with a through tubing inflatable packer and a cement cap topped with mud push and high viscosity gel to reduce the cement slumping effect.
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