Total E&P Indonesie (TEPI) has been drilling in the Tunu, Tambora, and Handil (TTH) fields located in Delta Mahakam, East-Kalimantan of Indonesia. These fields have been producing gas for some decades in Indonesia. Casing cementation over weak formations and low fracture gradients are some of the major challenges encountered during operations in these fields; hence, designing and pumping lightweight slurry systems with superior performance when compared with conventional cement slurries is required to overcome the aforementioned operational challenges. Historically, slurries in TTH have been designed with conventional cenospheres as the extender; cenospheres are a byproduct of coal combustion at thermal power plants, and, in some cases, cementing operations would either face lost circulation or sustained casing pressure (SCP) or a combination of both due to cenospheres crush and an increase in downhole density. An alternative method was needed to replace the existing cenosphere-based system and prevent lost circulation, which mainly occurs due to slurry instability and higher downhole density. A comparison study required collection of four different samples of engineered glass bubble extenders. This paper describes the results of an extensive, thorough study on different slurry designs to replace the current method with a new system to minimize the risk of lost circulation and eventually reduce the risk of SCP which, in some cases, is a consequence of lost circulation. Field implementation results of the new system confirmed an effective reduction in the number of wells encountering lost circulation during cementation. The comparison of cementation with both systems in the same field in more than 150 wells is presented in this paper to provide a case history that reflects operational improvements achieved by using the engineered highly crush-resistant cement slurry system.

Traditionally, service companies have had to place several consecutive cement plugs to successfully kick off wells deeper than 3,500 meters. Within the scope of integrated projects in Southern Mexico where wells are usually deeper than 5,000 meters, the low success rate for traditional balanced plug cementing has jeopardized operational efficiency and financial results. Several plug failures made it clear that the volumetric calculations and other known engineering best practices that were implemented were not sufficient to bring the success rate to an acceptable level. In our field study, we implemented an innovative simulation and design method that allows for engineered optimization of the plug placement design and that shows how a 100% success rate in plug cementing can be achieved in wells as deep as 5,720 meters, with hard formations and an OBM environment. The value of this new method resides in a live analysis and display of the fluid interfaces, mixing both while traveling down the pipe and up the annulus and resulting in the output of an estimated top of uncontaminated cement after pulling the pipe out of the hole. The new workflow reveals the effect of each variable affecting the amount of contamination of the cement slurry downhole and gives the engineer the opportunity to optimize the plug placement design before job execution to reach the highest possible top of uncontaminated cement after execution. The results obtained with the new engineering tool and a precise operational field execution has moved the theory of plug placement from the best practice library to the reality of the plug placement operations.

The loss of circulation during well drilling and cementing jobs is a serious problem for the oil and gas Industry. Loss of time is very costly and wellbore erosion can lead to inadequate zonal isolation putting the long-term integrity of the well in jeopardy. Lost circulation was a major challenge experienced by an operator when drilling wells in their 2011 campaign. The site geological prognosis indicated a high degree of depletion in sands and presence of natural fractures. As anticipated, severe lost circulation while drilling was experienced in these formations and drilling efficiently proved to be a challenging process due to heavy mud losses. An engineered fiber-based loss circulation control pills (EFLCC), based on special engineered fiber system and using a particle size distribution principle were developed to address this issue. The combination of fibers, special solids, and cementitious material was designed and tested in the laboratory to validate its ability to bridge the loss zone while permanently sealing the losses allowing further drilling to the next casing point. This paper presents the case history and field application of these novel engineered fiber-based loss circulation control pills for the successful treatment of heavy mud losses to formation in wells in offshore gas fields in Indonesia. The paper also includes a discussion of the methodology, material properties and applications.

The well construction strategy for the Deepwater Malikai project, Malaysia, included 36-in. structural pipe jetting and 13 5/8-in. surface casing riserless cementing for top-hole sections with the objective for further development of lower sections with tension leg platform (TLP). Cementing of the 17 ½-in. surface hole mainly dominated by shale formation and penetrating multiple shallow faults required isolating shallow gas sands by bringing top of cement to the seabed, thus meeting the well integrity requirement stipulated by the Malaysian Petroleum Management (MPM).The cement slurry design for the 13 5/8-in. casing with riserless mud recovery system includes selection of lightweight trimodal particle-size distribution cement blend optimized with a gas migration control agent and low-temperature dispersant. This mitigates dynamic losses in unconsolidated formations and faults having narrow margins between pore and fracture pressures. Cement slurry achieves faster compressive strength and static gel strength development at lower seabed temperature, preventing casing subsidence and providing good shoe strength. The cement job design respects density and friction pressure hierarchies, providing flat fluid interfaces between successive fluids pumped, combined with optimal casing standoff and displacement efficiency ensuring effective mud removal in highly deviated largeannulus top-holes. This paper will discuss the extensive laboratory testing employed to qualify the engineered trimodal lightweight cement slurry design and effective mud removal strategy fit for the applications on the seven batch-set top-hole sections, achieving zonal isolation requirement.

The optimization of spacer fluid properties is very critical for achieving good mud removal in primary cementing. A new, laminar spacer fluid formulation using surfactant/solvents based on engineered-chemistry approach and incorporating high-temperature mud removal (HTMR) fibers was introduced to improve cementing placement results for a major operator in the Gulf of Thailand. The successful implementation of this technology has been accomplished in the field through the application of the Design-Execution-Evaluation workflow best practices. The team carried out extensive laboratory testing to validate placement efficiency at conditions representative of high-temperature production tubing jobs. A detailed analysis was carried out to compare performance (with fibers) with the legacy system (without fibers) from the same field. The testing results showed significant improvement in the stability of the new system at high temperature and a much higher cleaning efficiency attained using a proprietary test method. Repeat tests were conducted in different laboratories to ensure reliability and robustness against minor changes in downhole temperature. In order to achieve complete tubing annulus integrity the design workflow required mandatory mitigations for 4 main phenomena (i.e. microannulus, channeling, gas migration and set cement delamination) which, based on detailed analysis of actual data from treated wells, were the main risk factors that could cause integrity issues. This thesis is consistent with indepth analysis of previous wells and therefore supported the introduction of a more technically robust spacer in the production string cementation fluids train to eliminate the risk of channeling. Prior to actual field implementation of the system on the first well, a dummy "yard" test was carried out onshore to validate mixability and pumpability under simulated field conditions. For operation integrity, a pre-job quality checklist system plus technical co-ordination was implemented between operator fluids team, service company technical engineers and rig-based personnel - this included use of standardized peer review, risk assessments, materials preparation & logistics workflows, plus the application of ISO-certified quality assurance procedures. Three case histories from numerous successful jobs will be presented in this paper.