The objective of most acid stimulation treatments in Saudi Arabia’s Khuff carbonate formations is to remove drilling induced damage and achieve maximum well productivity. Open hole and multilateral completed wells, present several challenges that prevent an optimum intervention and placement of fluids with coiled tubing (CT). Traditional stimulation practices of these types of producers usually involve spotting fluid systems comprising multiple stages of pre-flushes, acid, and chemical diverting agents along the horizontal section of a well without adequate control over treating fluids’ placement and displacement. An innovative approach, combining fiber optic enabled coiled tubing (FOECT) and distributed temperature survey (DTS) recorded data with reservoir data to selectively place stimulation fluids in targeted formation sections, was successfully field tested in a dual-lateral horizontal gas well completed open hole in Saudi Arabia. This paper describes the job design, the operations performed to access the desired lateral, and the stimulation treatment performed combining the two technologies. Details on how the DTS technology was used to identify thief zones during the actual stimulation treatment, and how the placement of treatment fluids was optimized along the horizontal section, are also provided. The successful implementation of the first field trial has provided a strong incentive to utilize a similar approach in other gas producers currently scheduled.

The objective of many matrix acidizing treatments in the Khuff carbonate formations is to remove drilling damage and enhance productivity after the drilling process. Open hole and multilateral completed wells, present several challenges that prevent an optimum intervention with coiled tubing (CT). Traditional practices have been limited to spot stages of pre-flushes, acid, and diversion systems in front of the formation from toe to heel without proper control over the placement process. Using an innovative workflow, interpretation of distributed temperature surveys (DTS) responses, correlated with reservoir data, assists in selectively placing fluids, maximizing the contact of stimulation fluids with the targeted formation sections. Two field applications, in dual-lateral horizontal open hole gas producers, that demonstrate how to optimize a stimulation treatment as it occurs, were implemented in a field in the Kingdom of Saudi Arabia. In both cases, selective access to pay zones in each lateral was confirmed with DTS profiles. Following the pre-flush and the first acid pass, DTS measurements indicated acid effect over the permeable zones but also detected fluid movement towards non gas bearing thief zones. Foam and energized visco-elastic diverting acid fluids were used to divert acid to the target zones avoiding the lost of all stimulation fluids to the toe in one case and to the heel in the other well. After treatment, the gas production increased from zero to more than two times the expected rate in both wells. Understanding of the flow patterns as fluids are placed in the wellbore was possible. Changes to the fluid placement schedule during the job resulted in optimum acid coverage and efficient diversion confirmed by the downhole measurements. The identification of the thief zones was critical to avoid wasting fluids. This experience, the first ever gas wells in Middle East, represents an opportunity for un-locking production potential in similar gas developments.

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The number of multilateral gas producers drilled in the Ghawar field has significantly increased over the past few years as part of the reservoir development strategy to maximize well productivity through maximum reservoir contact. Although these wells are expected to require little rigless intervention to conduct surveillance or productivity enhancement work, the effective options available to selectively access each of the laterals are limited. Thus specialized tools and techniques are required but the complex nature of these deep wells, combined with the high pressure and temperature characteristics of the reservoir, makes their application difficult and the outcome of the well intervention procedures uncertain. One of the techniques that has proven successful in different fields around the world, is the use of a lateral accessing tool to selectively access the desired lateral to then perform a stimulation treatment, run a production log, or any other operation. Combining lateral accessing and high-pressure jetting tools to access and stimulate two under-performing laterals a world first, was done in Well A, a producer drilled in a carbonate reservoir in Saudi Arabia's Ghawar field. The stimulation treatment was successful and the well achieved a two-fold rate increase. This paper provides details about the pre-job research and testing conducted, the methodology, equipment and procedure successfully applied in dual-lateral Well A, and lessons learned throughout the operation. The post-treatment performance of the well was better than anticipated, which encouraged Saudi Aramco to further utilize the technique for different applications. Introduction Although lateral accessing tools have been successfully used in wells around the world over the past few years, the gas producer selected for the first trial of this technique posed considerable challenges because of its casing size and the long length and heavy weight of the bottom-hole assembly, comprising the accessing and high jetting tools, that was run on coiled to access the lateral sections. Multilateral candidates provide options to increase the productivity of gas fields during their productive lives, using an effective stimulation treatment. This was the first successful attempt to access each lateral in a multilateral well. Previous unsuccessful attempts resulted in having to bullhead stimulation treatments in wells with a similar configuration, with relatively poor results.